Free · Unit conversions

Metric Scales, Inches & Customary Lengths Converter

Convert metric scales, inches & customary lengths with exact unit definitions and editable results.

  • Formula & worked example
  • Private in your browser
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Calculator inputs

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How to use this calculator

  1. Enter the known values in the units shown. Results update as you type.
  2. Where results are editable, change one to solve backwards. Lock a value to hold it fixed.
  3. Use the worked example to check the method. Reset restores the starting fields.

Private by default

Inputs and results stay in this browser tab. Bookify does not upload or store the values you enter.

Formula and method

304.8 mm = 30.48 cm = 0.3048 m = 12 in = 1 ft. The extra metric and customary fields let you choose scales from very small metric units through miles. Ordinary feet and inches use international definitions.

304.8 mm = 30.48 cm = 0.3048 m = 12 in = 1 ft

Worked example

Enter these known values and leave the other values blank.

Length in millimeters
304.8 mm
Length in centimeters
30.48 cm
Length in meters
0.3048 m
Length in kilometers
0.0003048 km
Length in other metric units
304800 μm
Length in inches
12 in
Length in other imperial units
1 ft

Assumptions and limitations

  • The extra metric and customary fields let you choose scales from very small metric units through miles. Ordinary feet and inches use international definitions.
  • These are linear lengths, not areas or volumes. Square and cubic units require squared and cubed conversion factors.
  • The arithmetic accepts signed values for directed differences. Physical heights and ordinary distances should be entered as nonnegative magnitudes. Display rounding does not improve the precision of a measurement.

Common questions

Can I convert back from the result?

Yes. Enter a known value in another field and leave the original field blank. Every field describes the same underlying length.

How should I read a compound length?

When a compound unit is selected, use colons between the displayed components. A decimal value in feet is not the same as feet followed by inches.

References

The calculation equations, inverse formulas, units, and input rules were imported from this source. Bookify provides the interface and equation solver.

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