Pounds to Stones Converter

by

Enter pounds to see the matching stones and pounds weight, plus the same weight written in decimal stones.

Advanced options
Decimal stones will be shown to 3 decimal places.
Weight in stones and pounds Whole stones are groups of 14 pounds. The pounds after them come from the unrounded weight.
Weight in decimal stones This value is pounds divided by 14 and rounded only for display.
Conversion details
Whole stones This is the number of complete 14-pound groups.
Pounds remaining after whole stones For a valid weight, this is at least 0 lb and less than 14 lb.
Did we solve your problem today?

How to use our Pounds to Stones Converter

  1. Enter one weight in the Weight (lb) box, such as 170 or 170.5. You may also type lb or lbs after the number.
  2. Click Calculate to see the weight in stones and pounds, such as 12 st 2.5 lb.
  3. Open Advanced options to choose how many decimal places appear in the decimal-stones reading.
  4. Sanity-check the mixed-unit answer: the pounds after the stone value should be at least 0 lb and less than 14 lb. If not, check the weight you entered.
Example inputs for Pounds to Stones Converter
Example inputs for Pounds to Stones Converter

Definitions

Stone (st): A weight unit equal to exactly 14 pounds. [1]

Decimal stones: A weight written as one number of stones, such as 12.5 st.

Stones and pounds: A mixed-unit weight showing complete stones and pounds left over, such as 12 st 2.5 lb.

Remaining pounds: The pounds left after complete 14-pound stones are counted.

Common mistakes and quick fixes

Mistake: Reading 12.5 st as 12 st 5 lb.
Fix: A decimal part of a stone is not pounds. Since 1 st is 14 lb, 12.5 st equals 12 st 7 lb.

Mistake: Entering a range such as 160-170.
Fix: Enter one weight only. Choose the single reading you want to convert.

Mistake: Typing a comma in the wrong place, such as 1,40.
Fix: Use commas only for thousands groups, such as 1,400. Use a decimal point for part of a pound, such as 170.5.

Mistake: Rounding a scale reading before converting it.
Fix: Enter the decimal part shown by the scale. The converter keeps fractional pounds in the stones-and-pounds reading.

Mistake: Treating 0 lb as an error.
Fix: Zero is valid and converts to 0 st 0 lb.

Limitations & Key Assumptions / Boundary Conditions

  • The converter accepts weights of 0 lb or more. Negative weights are outside its input range.
  • The stones-and-pounds result keeps fractional pounds from the entered value and does not round them to a whole pound.
  • Changing decimal places changes only the displayed decimal-stones value, not the stones-and-pounds result.
  • A very small nonzero weight can round to 0 decimal stones at the selected precision. Use more decimal places or the higher-precision note in the result.
  • This is a unit conversion only. It does not account for scale accuracy, clothing, time of day, or differences between measurements.

Methodology

Calculation

One stone equals exactly 14 pounds. [1] The converter divides the entered pounds by 14 for decimal stones, then separates complete 14-pound groups from the pounds left over.

decimal stones = pounds / 14

remaining pounds = pounds % 14

whole stones = (pounds - remaining pounds) / 14

In the second formula, % means the remainder after division. For any nonnegative entered weight, remaining pounds are at least 0 lb and less than 14 lb.

Worked example

For 170.5 lb, 12 complete stones equal 168 lb because 12 times 14 equals 168. The remaining 2.5 lb gives 12 st 2.5 lb. Dividing 170.5 by 14 gives 12.178571..., which displays as 12.179 st when three decimal places are selected.

Rounding

The converter rounds decimal stones only after division. The stones-and-pounds reading uses the original pounds value, so changing decimal places cannot change that reading.

Sources

  1. Special Publication 811 | NIST