About & calculation methods
Updated September 16, 2026
Metric Flip is a free browser-based converter for everyday measurements. It brings six related tools into one screen so you can compare a recipe, room dimension, parcel weight, weather reading, or distance without creating an account. The conversion guide explains the assumptions behind the numbers so that a correct calculation is also used in the right context.
How the numbers are calculated
For length, mass, volume, area, and speed, each supported unit has a factor relative to a common unit. The calculation is: input × starting-unit factor ÷ destination-unit factor. For example, 250 centimeters becomes 250 × 0.01 ÷ 0.0254 = approximately 98.425197 inches.
The common units in the implementation are meters for length, grams for mass, liters for volume, square meters for area, and kilometers per hour for speed. Temperature is converted through Celsius, with the offsets described in the temperature guide.
Which definitions we use
Lengths use the international foot and mile. Mass uses avoirdupois ounces and pounds, with 14 pounds per stone. Volume uses US customary liquid measures. Knots use the international nautical mile. These choices are important: an imperial gallon, a troy ounce, or a historical US survey foot must not be silently treated as the similarly named unit in this tool.
Reference definitions are available from NIST Special Publication 811, Appendix B and its alphabetical conversion tables. NIST does not operate or endorse Metric Flip.
Display rounding and precision
The converter calculates with JavaScript numbers, then formats the output to up to eight significant digits and six decimal places. This keeps everyday readings compact, but it is not an arbitrary-precision calculator. Very small nonzero results can round to zero, and very large values lose fine detail. Change to a more suitable unit if the display hides a quantity you need to see.
The Swap button uses the displayed, rounded result as the new input. Repeated swapping can therefore introduce small rounding differences. For a fresh calculation, enter the original measured value again. The equality line is a readable rounded summary, not a claim that every displayed decimal is exact.
The precision of a measurement comes from the original measurement process. Converting a roughly measured 2 meters to many digits of feet does not remove uncertainty from the tape measure. For manufacturing tolerances, laboratory measurements, surveying, dosing, or other consequential work, use independently validated tools and the required measurement standard.
What stays on your device
The conversion itself runs in your browser. No account or server request is needed to calculate a result. The optional home-screen prompt stores a dismissal preference on your device. Hosting and third-party resources can still receive connection information when the site loads; see the privacy notice.
Corrections and maintenance
Our guide distinguishes exact unit definitions from rounded examples and practical estimates. When reporting a suspected error, include the input value, starting unit, destination unit, displayed result, and the source you compared it with. This makes it possible to distinguish a calculation defect from a different unit convention.