Free · Unit conversions

Customary to Metric Measurements

Convert related units within length, area, volume, mass and available temperature modes, preserving metric and customary alternatives.

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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.

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Formula and method

In length mode, 1 meter equals 100 centimeters and 1000 millimeters. The ordinary customary foot equals exactly 0.3048 meter.

Each row represents the same physical quantity; international inch = 0.0254 m; pound = 0.45359237 kg; US liquid gallon = 231 in³.

Worked example

Enter these known values and leave the other values blank.

Type of conversion
Length
Length in meters
1 m
Length in inches
39.37 in
Length in feet
3.281 ft
Length in yards
1.0936 yd
Length in miles
0.0006214 mi
Length in millimeters
1000 mm
Length in centimeters
100 cm
Length in kilometers
0.001 km
Length in nautical miles
0.00054 nmi
Length in radius of the Sun
1.4374e-9 R☉
Length in light years
1.057e-16 ly
Length in other units
6.685e-12 au

Assumptions and limitations

  • Select the quantity first. Rows within a mode are alternate representations of one measurement, not measurements to add. Temperature is an absolute reading, not a temperature difference.
  • The generic cup retains 236.59 mL, metric tablespoons and teaspoons are 15 and 5 mL. Earth mass (5.9722e24 kg), solar mass (1.989e30 kg), Earth radius (6371000 m) and soccer-field area (7140 m²) are explicit conventional approximations. They are not exact universal constants.
  • Atomic and particle masses use CODATA 2022 central values with uncertainty. A light-year is based on a 365.25-day Julian year; the parsec uses 648000 au/π and the nominal solar radius uses 695700000 m.
  • Clear an unknown before solving backward. Currency controls represent the chosen denomination without exchange rates; prices must use the selected denominator units.

Common questions

What is included in this estimate?

Select the quantity first. Rows within a mode are alternate representations of one measurement, not measurements to add. Temperature is an absolute reading, not a temperature difference.

References

Replace rounded liquid-volume and astronomical factors with definitions, and dated particle factors with CODATA 2022 central values. Retain all selectors. Enforce the documented geometric domains and positive whole counts.

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