Precision Scale Converter & Calculator
Common Presets
Scale Converter & Model Making Calculator: How It Works
Every scale is just a ratio: 1:72 means the model is one seventy-second of the real thing, in every dimension. The tricky part is never the idea — it’s doing the math across mixed units (a wingspan in feet, a model in millimeters) without a slip. That’s the whole job of this model making calculator and model scale converter above: type any two of real size, scale, and scaled size, and it fills in the third, in whatever units you happen to have. It also outputs the exact percentage to enter in a 3D-print slicer — see the dedicated percent scale calculator for slicer-specific workflows. Built by a product designer and 3D-printing hobbyist — more on why it exists.
How to Calculate Scale Manually
To find the Scaled Size manually, use the following formula:
Scaled Size = Real Size / Scale RatioExample: If you have a 10-meter wing (1000cm) and want to model it in 1:48 scale:
1000cm / 48 = 20.83cm
Essential Scale Conversion Reference
Want the full picture? Browse the complete scale chart with a dedicated calculator and conversion guide for every scale.
| Scale | Alias / Name | % Size | Ratio / Math |
|---|---|---|---|
| 1:12 | 1/12 Scale Action Figs | 8.33% | 1" = 1' |
| 1:18 | 1:18 Scale Diecast | 5.56% | 0.67" = 1' |
| 1:24 | 1/24 Scale Car Models | 4.17% | 0.5" = 1' |
| 1:35 | 1/35 Scale Military | 2.86% | 0.34" = 1' |
| 1:43 | 1:43 Scale O-Gauge | 2.33% | 0.28" = 1' |
| 1:48 | Quarter Scale Aircraft | 2.08% | 1/4" = 1' |
| 1:72 | Braille Scale Small Scale | 1.39% | 1/6" = 1' |
| 1:144 | 1:144 Scale Micro | 0.69% | 1/12" = 1' |
| 1:700 | 1:700 Scale Waterline | 0.14% | 0.4mm = 1' |
| 1:22.5 | Garden Scale G Scale | 4.44% | 0.533" = 1' |
| 1:48 | O Scale O Scale | 2.08% | 1/4" = 1' |
| 1:76 | OO Gauge OO Scale | 1.32% | 4mm = 1' |
| 1:87 | HO Scale HO Scale | 1.15% | 3.5mm = 1' |
| 1:120 | Table Top TT Scale | 0.83% | 0.1" = 1' |
| 1:160 | N Scale N Scale | 0.63% | 2mm = 1' |
| 1:220 | Z Scale Z Scale | 0.45% | 1.4mm = 1' |
| 1:20 | 1:20 Detail | 5.00% | 0.600" = 1' |
| 1:50 | 1:50 Section | 2.00% | 2cm = 1m |
| 1:100 | 1:100 Building | 1.00% | 1cm = 1m |
| 1:200 | 1:200 Site Plan | 0.50% | 0.5cm = 1m |
| 1:500 | 1:500 Urban | 0.20% | 2mm = 1m |
| 1:56 | 28mm 28mm Heroic | 1.79% | 0.214" = 1' |
| 1:64 | S Scale Hot Wheels | 1.56% | 3/16" = 1' |
| 1:100 | 15mm 15mm | 1.00% | 0.120" = 1' |
| 1:285 | 6mm Epic | 0.35% | 1.1mm = 1' |
Model Railroad & Hobby
Perfect for HO, N, and O scale layouts. Calculate exact dimensions for track beds, rolling stock, and scenery to ensure your world looks authentic.
- 1:87 (HO) - Most popular globally
- 1:160 (N) - Great for small spaces
- 1:48 (O) - Large, traditional models
Architecture & Engineering
Ideal for Site Plans and Blueprints. Convert real-world land plots into 1:50 or 1:100 architectural models with millimeter precision.
- Architectural - 1:50 & 1:100
- Engineering - 1:20 & 1:500
- Slicer Setup - Dimensional accuracy
Tabletop & 3D Printing
Essential for 28mm/32mm miniatures. Scaling STL files for resin printing requires exact ratios to maintain consistent sizing across armies.
- Warhammer - 28mm-32mm
- Historical - 15mm Grand Strategy
- Resin Scaling - Precise detail exports
Scale Calculator - Frequently Asked Questions
How do I calculate scale factor size?
This free calculator does it for you instantly — enter any two values above and it fills in the third. If you already know two measurements (a real size and a model size) and want the exact scale factor and ratio between them, use the dedicated scale factor calculator.
Can I use this as a model making calculator?
Yes — that's exactly what it is. Whether you're building a plastic kit, a diorama, an architectural study model, or scaling a 3D-print STL, the same math applies: type your real-world size, pick a scale, and read off the scaled size in mm, cm, or inches. For slicer percentages specifically, use the dedicated percent scale calculator.
What is the most common model scale?
1:72 and 1:48 are the most common for aircraft, 1:35 for military vehicles, and 1:87 (HO) for model railroading.
How do I convert imperial measurements to metric on this calculator?
Our tool supports bidirectional unit conversion. Simply select 'ft' or 'in' for the real size and 'mm' or 'cm' for the scaled size, and it handles the math automatically.
What is 1:1 scale?
1:1 scale, also known as 'full scale,' means the model or drawing is the exact same size as the real-world object. It represents a 100% size ratio.