Scale Calculator
Find real length, drawing length or a scale ratio. Mix length units and compare linear, area and volume scale factors with a size diagram.
YOUR CALCULATION
Result
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Calculation steps
Work through one step at a time or reveal the complete calculation. The steps use your current inputs.
How to calculate
The ratio is drawing length : real length, measured in the same unit. A 1:50 drawing has a real-to-drawing length factor of 50. Apply that factor once for lengths, twice for corresponding areas and three times for corresponding volumes.
real = drawing × (real ratio term / drawing ratio term); drawing = real / factor; area factor = factor²; volume factor = factor³
Worked example
At 1:50, a drawing length of 2 cm represents 100 cm = 1 m. At 2:1, a drawing length of 10 cm represents a real length of 5 cm. For 1:50, corresponding real areas are 2,500 times drawing areas.
Assumptions and input details
All ratios and lengths must be positive. Enlargement is allowed, such as 2:1. Area and volume factors assume geometrically similar objects. The print percentage is drawing/real × 100 relative to a full-size drawing, not a printer correction for an already scaled plan.
Unit definitions
Unit selection is independent of language. Each selector contains only units for its physical quantity. Calculations use defined base units internally.
Choose from 23 length definitions, including explicitly labelled regional measures. Area conversions square the length factor; geometric volumes cube it.
Regional measures are not interchangeable merely because their names look similar. This is a documented selection, not a claim to include every historical unit.
NIST measurement tables · Japanese traditional units · Mainland China and Hong Kong unit distinctions
Using this calculator
Can I enter my own problem?
Yes. Replace the example values with your own inputs. The result, calculation steps, tables and applicable diagrams update from those inputs. Blank or invalid values clear the result; example values are never silently substituted for missing inputs.
Are the results exact?
Results use floating-point arithmetic and displayed rounding. Read the formula, assumptions and any stated data precision before interpreting the result.
Is my input uploaded?
The calculation runs in your browser. No account, file upload or external AI service is required. Inputs are not saved between page reloads.
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A little space to keep the tools free.