⅛→
mm
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LineworkLab

Precision tools for makers, machinists & modelers

Machinists 3D Printing Scale Models Woodworking
// RAPID CONVERSION CALCULATOR
→
→
—
← Select a fraction OR type a decimal value. Conversion updates instantly.
Conversion Formula
mm = inches × 25.4
// 1 inch = 25.4 mm exactly (ISO 1:1964)
// FRACTIONAL INCH → DECIMAL → MM MATRIX Click row to highlight · Click header to sort
Fraction ▲ Decimal (in) ⇅ Millimeters ⇅ mm (3 d.p.) ⇅ Denominator ⇅

What is this chart?

This matrix covers every standard fractional inch from 1/64″ through 1″ — the full set used in machining, carpentry, 3D printing, and engineering.

Why 25.4 exactly?

Since 1959, one inch is defined as exactly 25.4 millimeters by international agreement. All values here are mathematically exact — not approximations.

3D Printing Use

Most slicers (Bambu Studio, PrusaSlicer, Cura) work in millimeters. Convert your imperial STL dimensions before slicing, or match printed parts to imperial hardware.

Machinist Reference

Use the decimal column for dial indicator readings and the mm column for metric technical drawings and CNC setups.

// GRID CONFIGURATION
5
5
0.4
1.2
// LIVE PREVIEW Letter · Portrait · 1:24 · 5 mm grid
Each minor square = 5 mm real · Each major square = 25 mm real · Scale 1:24

What is a scale grid?

A scale grid sheet lets you draw, plan, or trace objects at a proportional reduction. 1:24 means every 1 mm on paper equals 24 mm in the real world — perfect for half-inch-scale dollhouses and architectural mockups.

Common architecture scales

1:48 (¼″=1ft) is the most common U.S. architectural model scale. 1:24 (½″=1ft) for detail work. 1:12 for dollhouses where 1 inch = 1 foot.

3D Printing use

Print a 1:1 reference grid and lay your STL printed parts on top to verify real-world dimensions before committing to a full print run. Save filament by catching scaling errors early.

How to print

Click Print / Save as PDF. In your browser's print dialog, set margins to None and ensure Scale = 100% (not "Fit to page") for accurate grid dimensions.

// DOCUMENTATION

How to Use LineworkLab

Two tools, zero friction. Here's everything you need to get accurate results fast.

⅛
Tool 01
Fraction → MM Matrix
  1. 1
    Pick a fraction from the dropdown — every standard imperial fraction from 1/64″ to 1″ is listed with its mm value previewed inline.
  2. 2
    Or type any decimal inch value into the middle field — useful for dial indicator readings or dimensions from a drawing that aren't standard fractions.
  3. 3
    Read the result in the glowing right-hand display. The value is in millimeters, precise to 4 decimal places.
  4. 4
    Use the filter buttons (All / 64ths / 32nds…) to narrow the chart to the denominator family you're working in.
  5. 5
    Search the chart by typing a fraction, decimal, or millimeter value — matching rows highlight instantly. Click any row to lock it into the calculator.
  6. 6
    Sort any column by clicking its header — useful for finding the nearest metric size to a given mm value.
PRO TIP Type a millimeter value like 9.525 in the search box to instantly locate 3/8″ — great for reverse-lookup from metric drawings.
⊞
Tool 02
Scale Grid Builder
  1. 1
    Choose your paper size and orientation. Letter Portrait is standard for US workshops. A4 Portrait for metric-first workflows. Tabloid or A3 for larger plan sheets.
  2. 2
    Set your scale ratio from the preset list — 1:24 for half-inch dollhouse scale, 1:48 for quarter-inch architectural, 1:12 for full dollhouse scale — or enter a completely custom ratio.
  3. 3
    Adjust minor grid spacing (the small squares) in real-world millimeters. A 5 mm minor grid at 1:24 prints squares that represent 5 mm in reality — about 0.21 mm on paper.
  4. 4
    Set major grid frequency — every 5 minor lines makes a heavier major line, creating the classic graph-paper hierarchy that helps count large distances quickly.
  5. 5
    Choose a color scheme. Blueprint blue on white is the classic technical look. Dark background mode creates an actual blueprint aesthetic suitable for framing.
  6. 6
    Click Print / Save as PDF. In the browser print dialog: set Margins → None, set Scale → 100% (never "Fit to page"), and enable Background graphics if using a colored background.
PRO TIP Enable the title block and fill in your project name before printing — the stamp includes scale, paper size, and grid spacing so you'll always know what you're looking at months later.
// FAQ

Frequently Asked Questions

Common questions from machinists, 3D printing hobbyists, and scale modelers.

Divide the numerator by the denominator to get the decimal inch value, then multiply by 25.4. For example: 3/8″ → 3 ÷ 8 = 0.375 → 0.375 × 25.4 = 9.525 mm. The Fraction Matrix above does this instantly for every standard fraction from 1/64″ to 1″.

Since 1959, the international inch has been defined as exactly 25.4 mm by agreement between the US, UK, Canada, Australia, New Zealand, and South Africa (the "International Yard and Pound Agreement"). This means all values in this chart are mathematically exact — not rounded estimates.

1/4″ = 6.35 mm exactly. (0.25 × 25.4 = 6.35). Similarly: 1/8″ = 3.175 mm, 1/2″ = 12.7 mm, 3/4″ = 19.05 mm.

The most common US architectural model scales are:

  • 1:48 — Quarter-inch scale (¼″ = 1 ft). Most common for residential architectural models.
  • 1:24 — Half-inch scale (½″ = 1 ft). Good for detailed interior work.
  • 1:12 — Inch scale (1″ = 1 ft). Standard dollhouse scale, great for fine detail.
  • 1:96 — Eighth-inch scale (⅛″ = 1 ft). Used for site plans and large buildings.

Use the Grid Builder's scale preset to generate a correctly proportioned sheet for any of these.

Most slicers (Bambu Studio, PrusaSlicer, Cura, OrcaSlicer) work in millimeters. Use the Fraction Matrix to convert your imperial dimensions before modeling or before scaling STL files in your slicer. The Grid Builder can generate a 1:1 reference sheet — print it, lay your part on top, and visually verify real-world dimensions before committing to a full print run.

This is almost always a print scaling issue. Check three things in your browser's print dialog:

  • Set Scale to 100% — never use "Fit to page" or "Shrink to fit."
  • Set Margins to None — any margin will shift content and compress the grid.
  • Enable Background graphics — required if you're using a non-white background color.

Different browsers handle print scaling slightly differently. Chrome and Edge tend to be the most accurate for pixel-perfect canvas output.

Yes — select Custom… from the Scale Ratio dropdown and type 87. The grid will recalculate so that each printed square represents your chosen real-world spacing at 1:87 scale. Common model railroad scales: HO = 1:87, N = 1:160, O = 1:48, G = 1:22.5.

No. LineworkLab runs entirely in your browser. There is no server-side processing, no account system, no cookies, and no data collection of any kind. Every calculation and grid render happens locally on your device.

Both are exact — the 4 decimal place column (e.g. 9.5250) is useful for CNC programming and precision machining where thousandths of a millimeter matter. The 3 decimal place column (e.g. 9.525) is easier to read for general workshop use and is still more precise than most hand tools can measure.