Scale conversion calculator: real and model sizes

Convert real measurements to scale, scale to real, or between two scales. Choose units and ratios for drawings, maps and models.

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Set your data

Conversion type

Measurement to convert

Input unit

Output unit

Starting scale 1 :

Target scale 1 :

Nonnegative measurements up to one billion; denominators from 0.000001 to one billion. Units: mm, cm, m, km, inches and feet. Converts lengths, not areas or volumes.

Result

Enter your values to see the result.

Download result

Scale ruler

Change the length, units or scale to compare the two lengths. The buttons set the drawing scale, or the target scale when comparing two drawings.

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How to use the tool

Change the length, units or scale to compare the two lengths. The buttons set the drawing scale, or the target scale when comparing two drawings.

Choose real to scale, scale to real or between scales.
Enter the measurement, units and denominators of the 1:n ratios.

Method and principles

Units are converted first.

Real to scale divides by n; scale to real multiplies by n.

Between scales multiplies by starting n ÷ target n.

Formula

L₂ = \frac{L₁}{n}

Method and limits

Nonnegative measurements up to one billion; denominators from 0.000001 to one billion. Units: mm, cm, m, km, inches and feet. Converts lengths, not areas or volumes.

Inputs and results are processed in your browser and are not sent to the server. Aggregate statistics, when enabled, record only the tool and outcome, without the content.

Example

10 real meters at 1:100 are 10 cm on the drawing. A 10 cm model at 1:100 becomes 20 cm at 1:50.

Practical example

Input

Conversion type: Real → scale
Measurement to convert: 10
Input unit: m
Output unit: cm
Target scale 1 :: 100

Result

10 cm

Calculation steps

m → cm
$10 \times 100 = 1000$
1:100
$\frac{1000}{100} = 10$

10 m · 1:1 → 1:100

Frequently asked questions

How do I reverse a conversion?

Reverse conversion swaps the units and uses the result as the new input. The button is available when that value is within the input range.