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AutoCAD Scaling & Units — Complete Reference App

A free, web-based toolkit built for AutoCAD drafters at every level. Every page handles one specific part of the scaling and units workflow — look it up, grab the number, and get back to drawing. No account, no installation, works offline once loaded.

36
Reference Tools
5
Core Rules
6
Master Formulas
8
System Variables
⚡ New here? Start in 4 steps
1
Open Home — scan the reference card to orient yourself
2
Use Scale Calc — pick your discipline + scale, copy all values
3
Set up your drawing with the Setup Wizard
4
Use Search any time you need a specific command or concept
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All 37 Tools — Visual Directory
Click any card to open that tool
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Home / Reference Card
Start Here
Dense one-page cheat sheet — every scale factor, conversion, formula, and system variable you use daily. The fastest lookup in the app.
Best for: Quick lookups while actively drawing
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Scale Calculator
Most Used
Pick discipline + scale → instantly get Scale Factor, VP XP Zoom, LTSCALE, DIMSCALE, and a full text-height table. One-click copy buttons.
Best for: Setting up every value for a drawing scale
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Unit Converter
Live two-way converter: mm ↔ cm ↔ m ↔ decimal inches ↔ feet-inches ↔ decimal feet. Shows nearest standard fractions (to 1/64") as you type.
Best for: Mixing metric and imperial in one drawing
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Fraction Chart
Every 1/64" increment from 1/64" to 12" with decimal-inch and mm equivalents. Color-coded by fraction type. Searchable.
Best for: Converting bolt holes, tolerances, hardware dimensions
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Annotative Text
Complete guide to AutoCAD's annotative feature — how it works, how to set up text and dimensions to scale automatically across multiple viewports.
Best for: Multi-scale sheets with consistent annotation
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Title Block Setup
Step-by-step layout setup: Paper Space, Page Setup Manager, PDF plotter configuration, sheet size tables for ANSI/ARCH/ISO, discipline-specific scale recommendations.
Best for: Creating a print-ready layout from scratch
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Drawing Setup Wizard
Guided
Step-by-step wizard walks you through an entire new drawing setup: units, limits, layers, scale — in one guided flow with generated command output.
Best for: Starting a new drawing the right way
Hatch Calculator
Calculate the correct HPSCALE for any hatch pattern at any drawing scale, for both imperial and metric drawings.
Best for: Getting hatch spacing right at your plot scale
Command Aliases
Searchable full reference of AutoCAD keyboard shortcuts and command aliases — 100+ commands organized by category with descriptions.
Best for: Learning shortcuts to speed up your workflow
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LISP Scripts
AutoLISP routine reference and quick-use scripts for common AutoCAD automation tasks. Copy-paste ready routines for batch operations and productivity.
Best for: Automating repetitive drafting tasks
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LISP Snippets
AutoLISP / Visual LISP ready-to-load command snippets for AutoCAD 2024. Copy-paste code blocks for common automation, layer control, and drawing tasks.
Best for: Quick AutoLISP code you can drop straight into AutoCAD
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Layer Standards
Industry-standard layer naming conventions (AIA, NCS, discipline-specific) with colors, linetypes, and lineweights. Printable reference table.
Best for: Setting up a consistent, professional layer scheme
Linetype Guide
Visual guide to all AutoCAD linetypes with correct LTSCALE settings for each drawing scale. Shows actual dash-dot patterns at scale.
Best for: Fixing dashed lines that look wrong at plot scale
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Viewports & Paper Space
Complete viewport reference: creating, scaling, locking, per-viewport layer control (VPLAYER), clipping, and the Model Space vs Paper Space concept explained visually.
Best for: Understanding and controlling viewports
Dimension Styles
DIMSTYLE guide: setting DIMSCALE, arrow sizes, text placement, tolerances, overrides. Comparison of annotation vs non-annotation dimension workflows.
Best for: Getting dimensions to plot at the correct size
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External References (Xrefs)
XREF attach, overlay, bind, detach, reload, clip. Managing xref scale mismatches between metric and imperial files. eTransmit for sharing.
Best for: Collaborating across disciplines with linked files
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Sheet Set Manager
SSM from scratch: create sheet set, link drawings, insert SSFIELD title block fields, batch publish multi-sheet PDF. Page setup overrides and callout blocks.
Best for: Managing a full drawing set as one project
Blocks & Attributes
BLOCK, WBLOCK, INSERT, ATTDEF — all attribute modes explained with AFLAGS. Dynamic blocks (BEDIT). DATAEXTRACTION workflow. Block vs Group vs Xref comparison.
Best for: Creating reusable intelligent symbols
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Plot / Print Setup
Full PLOT dialog guide: plot area options, CTB vs STB plot styles, PDF output with DWG To PDF.pc3, PUBLISH batch workflow, PAGESETUP named setups, lineweights.
Best for: Getting clean, correctly scaled prints and PDFs
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Drawing Health & Audit
9-step diagnostic checklist (AUDIT → PURGE ×3 → OVERKILL → SCALELISTEDIT → Regapps → ISAVEPERCENT → SAVEAS), PURGE deep dive, file recovery escalation guide with canvas diagram.
Best for: Fixing bloated or corrupt drawings
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Template (.dwt) Builder
10-step interactive wizard for building a master template: units, limits, layers, text/dim styles, linetypes, paper space, title block, SAVEAS .dwt. Layer name builder generates -LAYER command strings. Discipline standards grid for 6 disciplines.
Best for: Creating firm-standard templates that eliminate per-project setup
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Tables & Data Links
TABLESTYLE reference, step-by-step Excel data link workflow (DATALINK → DATALINKUPDATE), FIELD code builder with 8 ready-to-use codes, EXTRACTDATA/EATTEXT for live block attribute schedules. Essential for pole schedules and equipment BOMs.
Best for: Live schedules linked to Excel and auto-updating title block fields
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What's New
App version history from v1.0 through v5.0 (36 pages), feature changelog with tagged entries, app stats, and roadmap including SDG&E manual library and Flutter native app.
Best for: Seeing what's been added and what's coming next
Electrical Utility Reference
Utility
Purpose-built for electrical utility drafting: interactive pole schedule builder with CSV/DATALINK export, NESC clearance calculator, 40+ conductor lookup (ACSR/AAC/AAAC/ACSS/URD), NRECA layer standards, one-line symbols, and common utility drawing types.
Best for: Distribution/transmission pole and conductor work in AutoCAD
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Conductor Sag Calculator
Utility
Parabolic sag calculator for overhead conductors (ACSR, AAC, AAAC, ACSS, copper). Enter span, initial tension, and target temperature — get sag, wire length, and tension. Temperature comparison table −20°F to 212°F. NESC clearance check for 11 crossing types. SVG catenary profile diagram.
Best for: Field stringing tables, NESC clearance verification, sag-tension spot checks
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Pole Loading Calculator
Utility
Wood pole structural analysis per NESC. Pick species (SY Pine, Douglas Fir, WRC, LP/JP), class, and height. Add conductor and equipment rows for wind and vertical loads. Computes overturning moment vs. ANSI O5.1 capacity with Grade B (SF=4.0) and Grade C (SF=2.0) pass/fail. SVG pole load diagram.
Best for: Preliminary pole strength checks on distribution and transmission structures
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Conduit Fill Calculator
Utility
NEC conduit fill calculations — select conduit type and size, add conductors, and instantly see the fill percentage with pass/fail against NEC limits (40% for 3+ conductors).
Best for: Verifying conduit capacity on underground and riser designs
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Wire Ampacity Reference
Utility
NEC ampacity tables for copper and aluminum conductors in conduit and free air. Includes correction factors for ambient temperature and conduit fill.
Best for: Conductor sizing checks on service and distribution work
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Transformer Sizing
Utility
KVA sizing calculator for single-phase and three-phase transformers. Enter load, voltage, and power factor to get required KVA with derating guidance.
Best for: Sizing pad-mount and pole-mount transformers from load data
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OH Const Stds Reference
SDG&E
SDG&E Overhead Construction Standards reference — sortable change log, standard number lookup, and expandable section tree. 842-page manual indexed with filterable history dating back to 2019.
Best for: Looking up OHCS standard numbers and tracking recent revisions
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OHCS Reader
SDG&E
Full 842-page PDF.js reader for the SDG&E Overhead Construction Standards. Chapter sidebar navigation, full-text search with page scan, zoom controls, and keyboard navigation. Load your local PDF — renders clean with no ghost text.
Best for: Reading OH Construction Standards in-browser with chapter nav
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EDD Manual Reference
SDG&E
SDG&E Electric Distribution Design Manual reference — 32-entry change log (DM2019–DM2025), standard lookup, and 13-section chapter tree covering DM 5000–6300.
Best for: Tracking EDD revisions and locating design manual sections
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EDD Reader
SDG&E
Full 486-page PDF.js reader for the SDG&E Electric Distribution Design Manual. 15-section sidebar (Front Matter + DM 5000–6300), full-text search, zoom, and keyboard navigation.
Best for: Reading the EDD Manual in-browser with section navigation
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UG Const Stds Reference
SDG&E
SDG&E Underground Construction Standards reference — 86-entry change log (2019–2026), standard lookup, and 21-section chapter tree covering UG 3000–5000. The most comprehensive of the three SDG&E manual references.
Best for: Looking up UG standard numbers and change history
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UGCS Reader
SDG&E
Full 1,044-page PDF.js reader for the SDG&E Underground Construction Standards. 21-section sidebar covering substructures, transformers, terminations, lighting, grounding, and trenchless construction. Full-text search and zoom.
Best for: Reading UG Construction Standards in-browser with section navigation
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Scientific Calculator
Full-featured scientific calculator with trig functions (sin, cos, tan and inverses), logarithms, exponents, memory, and engineering notation. Works offline.
Best for: Engineering math on the job without leaving the app
Chemistry Reference
Interactive periodic table with element detail lookup — atomic number, mass, symbol, electron config, and physical properties. Useful for material identification in fabrication and utility work.
Best for: Quick element or material property lookups
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Search
Full-text search across all 37 tools by keyword, command name, or concept. Filter by tool type. Finds the right page in under 2 seconds.
Best for: "I know what I need, not where to find it"
Help (You're Here)
This Page
Complete user guide — all tools explained, core rules, master formulas, system variables, and mobile/offline tips. Bookmark for reference.
Best for: Learning the app or understanding a concept
The 5 Core Rules
Run through this list whenever something looks wrong — you'll find the problem
01
Draw at 1:1 in Model Space. Always.
Real-world size, no scaling, no exceptions. A 30-foot wall is drawn 360 units long (1 unit = 1 inch). All scale control happens in the viewport — never in the drawing itself.
02
Set INSUNITS and UNITS before you draw anything.
Lock in your unit system before drawing or inserting a single object. Changing INSUNITS later does not rescale existing geometry — it only affects future insertions.
03
Scale Factor drives everything.
One number — the Scale Factor (SF) — controls LTSCALE, DIMSCALE, text height, and viewport XP zoom. Find it in Scale Calculator, write it down, apply it everywhere.
04
Lock viewports immediately after setting scale.
An unlocked viewport can be accidentally scrolled, silently breaking your plot scale with no visible warning until print time. Lock every viewport the moment you set it.
05
Convert everything to one unit system before mixing.
If you're combining files from different disciplines or countries, pick one unit system and convert everything into it before the project starts. Use XREF scale override to handle mismatches on the fly.
💡 Quick diagnostic: Use the DIST command to measure a known real-world dimension. If AutoCAD's number doesn't match reality, you have a unit or scale mismatch — go back to INSUNITS and UNITS.
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Master Formulas Explained
Know these six and you never need a lookup table again
SF = Real ÷ Drawing
Scale Factor — how many drawing units fit in one real-world unit at your chosen scale. For 1/4"=1', real=12", drawing=0.25", so SF = 12÷0.25 = 48.
VP Zoom = 1 ÷ SF
Viewport XP Zoom — the number you type after the zoom command in a Paper Space viewport. For SF=48, type 1/48xp. Locks your view to the exact drawing scale.
Text Height = Print × SF
Model Space text height — text drawn in Model Space must be BIG so it prints at the correct size. Multiply your desired print height by the SF. To plot at 1/8" with SF=48: draw text at 6.0" tall.
LTSCALE = SF
Linetype scale — one command, one number. Set LTSCALE equal to your Scale Factor and your dashed lines will look correct at your drawing scale. Also set PSLTSCALE = 1.
DIMSCALE = SF
Dimension scale — same idea as LTSCALE but for dimension arrowheads, gaps, and text. Set equal to your Scale Factor. If using annotative dimensions, set CANNOSCALE instead.
mm→in = × 0.03937
Metric-to-Imperial import — when bringing a metric file into an inch drawing, scale it by 0.03937 (= 1 ÷ 25.4) to correct the size. AutoCAD handles this automatically when INSUNITS is set correctly on both files.
⚠️ Think of Scale Factor as the master key: Once you know it, you can derive every other number. LTSCALE = SF. DIMSCALE = SF. VP Zoom = 1/SF. Text height = desired print height × SF.

Imperial vs Metric Scale — How They Work Differently

Architectural / Imperial: Scales written as "1/4 inch = 1 foot" mean 1/4" on paper = 12" in real life. The SF is 48 (= 12 ÷ 0.25). One drawing unit = 1 inch.

Civil / Engineering: Scales written as "1 inch = 50 feet" mean 1" on paper = 50' in real life. One drawing unit = 1 foot. The SF is 50. If units were in inches instead, SF would be 600 (50 × 12).

Metric: Scales written as 1:100 mean 1 mm on paper = 100 mm in real life. The SF is simply the second number (100). One drawing unit = 1 mm.

Architectural 1/4" = 1'-0": SF = 48 | VP Zoom = 1/48xp | LTSCALE = 48 | Text at 1/8" = 6" tall in model Civil 1" = 50' (unit=1 ft): SF = 50 | VP Zoom = 1/50xp | LTSCALE = 50 Metric 1:100 (unit=1 mm): SF = 100 | VP Zoom = 1/100xp | LTSCALE = 100
System Variables Quick Reference
Type any of these at the AutoCAD command line to check or change the value
VariableType / AliasWhat It DoesWhat to Set It To
UNITSDialog / UNSets drawing unit type, precision, and insertion scale. Start every new drawing here.Your discipline: Architectural, Engineering, Decimal, Metric
INSUNITSInteger 0–20Controls auto-scaling when inserting blocks or XREFs. Critical for mixing metric and imperial files.1 = inches, 4 = mm, 6 = meters. Set once per drawing.
MEASUREMENT0 or 1Selects which linetype and hatch pattern library AutoCAD loads (imperial vs metric).0 = imperial, 1 = metric
LTSCALEDecimal numberGlobal linetype scale. Controls how dashed/hidden lines look. Wrong value = dashes too big or invisible.= your Scale Factor (SF)
PSLTSCALE0 or 1Makes linetype scale relative to viewport scale in Paper Space. Keep at 1 — makes linetypes look right in all viewports.1 (default — keep here)
DIMSCALEDecimal numberScales all dimension components: arrows, gaps, text, ticks. Set equal to SF for non-annotative dimensions.= your Scale Factor (SF)
CANNOSCALEScale stringActive annotation scale. Must match your viewport scale when using annotative objects.Match to viewport scale, e.g. "1/4" = 1'"
HPSCALEDecimal numberDefault hatch pattern scale. Set equal to your Scale Factor so hatch spacing looks correct when plotted.= your Scale Factor (SF)
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Unit Concepts — Arch vs Civil vs Metric
The most common source of confusion when mixing drawings from different disciplines

What Does "1 Drawing Unit" Mean?

AutoCAD doesn't know inches from millimeters — it just knows numbers. "1 drawing unit" means whatever you tell it to mean when you set INSUNITS and UNITS. This is the single biggest conceptual hurdle for new drafters.

Discipline1 Unit =INSUNITSDisplay FormatExample: Draw a 30' wall
Architectural1 inch11'-6" (feet-inches)Type 360 (30 ft × 12 in)
Engineering1 inch11'-6.000" (decimal feet-in)Type 360
Civil / Survey1 foot230.0000 (decimal feet)Type 30
Metric1 mm49144.0000 (decimal mm)Type 9144 (30 ft in mm)
Metric (large)1 meter69.1440 (decimal m)Type 9.144 (30 ft in m)
⚠️ The classic mistake: An engineer sends you a metric drawing where their "9000" means 9 meters. You open it in your architectural inch drawing — AutoCAD now reads "9000" as 9000 inches (750 feet). The geometry looks enormous. Fix: XREF with scale override, or use INSUNITS = 4 on the source file and INSUNITS = 1 on your drawing so AutoCAD auto-scales on insert.

Architectural vs Engineering Display Format

Both Architectural and Engineering units use 1 unit = 1 inch, but they display the same distance differently:

18 drawing units stored internally: Architectural displays: 1'-6" (feet and whole inches) Engineering displays: 1'-6.0000" (feet and decimal inches) Both are exactly the same physical distance — just formatted differently.
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Calculators & Converters
Scale Calculator · Unit Converter · Fraction Chart · Hatch Calculator

📐 Scale Calculator

Pick a discipline and scale from the dropdowns — the results panel fills in every value you need in one shot. No math required.

💡 Enter a custom Scale Factor directly if you already know the number — the calculator works both ways.

🔄 Unit Converter

Two input panels — Metric (left) and Imperial (right). Type any value into any field and all others update instantly. The orange Nearest Fraction panel shows the closest standard fraction to any decimal you enter, with a green ✓ when it's exact.

Type 152.4 in Millimeters → sees: 6.000" decimal | 0'-6" feet-inches | 0.500 decimal feet | 6" exact ✓ Type 2 ft + 6.75 in → sees: 774.700 mm | 30.500" decimal | 2.542 decimal feet

½ Fraction Chart

768 rows covering every 1/64" increment from 1/64" to 12". Color-coded by fraction denomination. Jump buttons skip directly to any whole inch. Type any fraction, decimal, or mm value in the search box to filter live.

▦ Hatch Calculator

HPSCALE = Scale Factor in most cases, but some hatch patterns have a base scale built in that requires adjustment. The calculator handles the pattern-specific math for you — enter your drawing scale and the pattern name to get the correct HPSCALE.

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Drawing Setup Tools
Setup Wizard · Title Block · Annotative Text

🧙 Drawing Setup Wizard

Guided step-by-step flow for new drawings. You answer questions about discipline, paper size, and scale — the wizard builds the complete command sequence. Copy and paste straight into AutoCAD:

📋 Title Block Setup

Covers the full layout-to-print workflow. If Scale Calculator tells you what your numbers are, this page tells you where to put them:

💡 Golden rule of layouts: Always plot at 1:1 from Paper Space. Your viewport handles the drawing scale. Never scale the plot itself.

🔤 Annotative Text

Annotative objects scale themselves automatically based on the viewport's annotation scale setting (CANNOSCALE). One text or dimension object can display at the correct size in multiple viewports at different scales simultaneously. The page covers setup, the CANNOSCALE workflow, and common annotative vs non-annotative comparison.

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Reference Guides
Layers · Linetypes · Viewports · Dimension Styles · Command Aliases

🗂 Layer Standards

Layer naming follows industry standards (AIA, NCS) so every drafter on a project team can instantly recognize what's on a layer. The page provides color-coded tables for Architectural, Civil, Electrical, Mechanical, and Structural disciplines. Each layer entry shows name format, color number, linetype, and lineweight.

〰 Linetype Guide

Shows every standard AutoCAD linetype with a visual preview of its dash-dot pattern and the correct LTSCALE to use at each common drawing scale. Covers both imperial and metric pattern files (.lin). If your hidden lines print as solid, or your centerlines have no pattern visible, this page diagnoses it.

🖼 Viewports & Paper Space

The most misunderstood concept in AutoCAD, explained step by step with diagrams. Covers: creating viewports (MVIEW), setting scale (zoom XP), locking, VPLAYER per-viewport layer freeze, viewport clipping, multiple viewports at different scales on one sheet, and PSLTSCALE.

↔ Dimension Styles (DIMSTYLE)

DIMSTYLE controls every visual aspect of dimensions: arrow type and size, text height and position, extension line gaps, tolerances, and units. The page covers setting DIMSCALE vs using annotative dimensions, creating a firm-standard style, and overriding individual dimension properties without breaking the parent style.

⌨ Command Aliases

Searchable reference of all 100+ standard AutoCAD command aliases organized by category: Draw, Modify, Dimension, View, Layer, Block, and Settings. Shows both the alias (e.g., L) and the full command (LINE) with a short description. Learning 20–30 key aliases cuts drafting time significantly.

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Advanced Tools
Xrefs · Sheet Set Manager · Blocks & Attributes · Plot / Print Setup

🔗 External References (Xrefs)

Xrefs let you link one drawing into another as a live reference — the host drawing always reflects the latest saved version of the source. Key concepts covered on the page:

📋 Sheet Set Manager (SSM)

SSM organizes an entire drawing set as a project, not just individual files. Three-tab interactive panel with step-by-step guide:

▣ Blocks & Attributes

Three-tab interactive reference:

🖨 Plot / Print Setup

Everything about getting a clean print:

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Mobile, Offline & PWA Install
Use the app on your phone, tablet, or without internet

Install as a Phone App (PWA)

This app is a Progressive Web App (PWA) — it can be installed directly to your iPhone or Android home screen and used like a native app, with no App Store required.

Offline Use

Once you've visited the app at least once, the service worker caches all 36 pages, icons, and the PDF reference card to your device. After that, the app works with no internet connection — useful on a job site with spotty signal.

💡 If a page shows outdated content, do a hard refresh (Ctrl+Shift+R on desktop, or close and reopen the app) to force the service worker to fetch the latest version.

Mobile Layout

Every page is fully responsive. On iPhone 17 Pro Max and similar large phones, the navigation uses a hamburger menu (☰) — tap it to expand the full list of 37 tools, then tap any link to navigate. Tables become horizontally scrollable. All interactive elements meet the 44px minimum touch target size for comfortable use with a stylus or gloves.

Printing Any Page

Press Ctrl+P (Windows) or Cmd+P (Mac) on any page. The navigation, buttons, and dark mode chrome are automatically hidden, leaving a clean ink-friendly version of the content with color coding preserved.

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Using Search
Find anything across all 37 tools in under 2 seconds

The Search page indexes all 37 tools by keywords, command names, and concepts. Type any of the following and it finds the right page instantly:

Filter results by category (Calculator, Guide, Reference) using the pill buttons above the results. Results show the tool icon, name, a description, and tag chips — click any result card to open that tool.

💡 If you're not sure which tool covers a topic, search first. The Search page is faster than scanning the nav bar.