Scale Conversion FAQ
Everything people actually ask about scale math, in one place. For hands-on conversion, head back to the calculator or browse the complete scale chart.
How do I calculate a scaled-down size?
Divide the real measurement by the scale ratio. A 7-meter tank in 1:35 scale is 7000 mm ÷ 35 = 200 mm long. The calculator does this instantly in both directions, including mixed metric/imperial units.
How do I find the scale factor between two objects?
Divide the real dimension by the model dimension (in the same unit). If a real 4,500 mm car measures 187.5 mm as a model, the scale is 4500 ÷ 187.5 = 24, i.e. 1:24. Leave the scale field empty in the calculator, enter both sizes, and it computes the factor for you.
How do I convert a model from one scale to another?
Multiply the model dimension by (old ratio ÷ new ratio). A 1:72 part converted to 1:48 grows by 72 ÷ 48 = 1.5×. See our scale-to-scale conversion pages for worked charts of the most common pairs.
What scale percentage do I enter in my 3D-print slicer?
Use 100 ÷ ratio. For a full-size STL printed at 1:56 (28mm gaming), set the slicer to 100 ÷ 56 ≈ 1.786%. To re-scale an STL that is already scaled, multiply by (old ratio ÷ new ratio) × 100 instead.
What is the most common model scale?
1:72 and 1:48 dominate aircraft, 1:35 dominates military armor, 1:24 model cars, and 1:87 (HO) is the most popular model railway scale worldwide.
What is 1:1 scale?
1:1 or "full scale" means the drawing or model is exactly the same size as the real object — a 100% size ratio.
What does "28mm" mean if it isn't a ratio?
Wargaming sizes like 28mm or 15mm describe a soldier's height to the eyes, not a ratio. 28mm works out to roughly 1:56 for vehicles and terrain; 15mm to roughly 1:100. Our scale pages list the ratio equivalents.
Why do HO and OO models look different sizes on the same track?
HO is 1:87 and OO is 1:76, but both run on 16.5 mm gauge track. OO models are about 14% larger than HO for historical manufacturing reasons, so mixing them is noticeable side by side.
How do I enter fractions like 10 1/2 inches?
Type them naturally — the calculator parses mixed numbers (10 1/2) and plain fractions (3/8) in any size field, and can display imperial results as fractions too.
Does the calculator store my data?
Saved calculations live only in your browser's local storage — nothing is sent to a server. That also means clearing browser data erases them, so use the CSV or PDF export in the Workbench History panel to keep permanent records.