What this calculator does
Convert stones to pounds, or pounds to stones, so a body weight from the UK or the US makes sense to you. A British weight of "12 stone" and an American weight of "168 pounds" describe the same person. Stones remain the normal way to state body weight in the UK and Ireland, while the US quotes pounds alone. Travelers, people reading health articles from the other side of the Atlantic, and anyone using a US-made scale in Britain all end up converting between them.
Both units belong to the same imperial family: one stone is exactly 14 pounds, by definition. That makes the conversion a whole-number multiplication or division with no rounding. Choose a direction and the result appears with the step that produced it.
Where it's used
Why this math matters outside the classroom:
- Body weight. A person weighing 12 stone weighs 12 × 14 = 168 lb.
- Mixed units. Someone listed at 10 st 6 lb weighs 140 + 6 = 146 lb.
- Horse racing. A jockey riding at 9 stone carries 126 lb.
- Pounds to stone. British readers picture a 200 lb person as 14 st 4 lb, since 14 × 14 = 196.
- Division with remainders. Students divide 185 lb by 14 to get 13 stone with 3 lb left over.
Grade level and standards: Grades 4–5; Common Core State Standards for Mathematics 5.MD.A.1. © Copyright 2010. National Governors Association Center for Best Practices and Council of Chief State School Officers. All rights reserved.
How to use it
- Enter the weight. For stones, use a decimal: 10½ st is 10.5.
- Choose stone to pounds or pounds to stone.
- Read the answer and compare it with the reference table of typical body weights.
What the inputs mean
- Value to convert
- A weight in decimal stones (for st → lb) or pounds (for lb → st).
- Direction
- Sets the conversion direction and the reference table.
Formula and method
lb = st × 14 st = lb ÷ 14
In the formulas, st is the weight in stones and lb is the weight in pounds. The stone is 14 avoirdupois pounds (the everyday pound used for body weight) by definition, so the factor is exactly 14 both ways.
Pounds to stone often gives a repeating decimal, because 14 = 2 × 7. 150 lb is 10.714285… st, which is cleaner to read as 10 st 10 lb.
Worked example
Convert a weight of 12 stone to pounds.
- Start from the exact factor: 1 st = 14 lb.
- Multiply the stones by 14 to get pounds: 12 × 14 = 168.
Result: 12 st is exactly 168 lb.
Understanding the result
To split a pounds figure into stones and pounds, divide by 14 and keep the whole number of stones. Then multiply the leftover fraction by 14, or subtract stones × 14 from the pounds. 150 lb ÷ 14 = 10.714…, and 150 − 10 × 14 = 10, so 150 lb is 10 st 10 lb.
Mental shortcut for stone to pounds: multiply by 10, then add 4 times the stones. 11 st → 110 + 44 = 154 lb, exactly. For a rough pounds-to-stone figure, divide by 15 and add a bit: 180 ÷ 15 = 12, and the exact answer is 12.86 st.
Reference values: 9 st = 126 lb; 10 st = 140 lb; 11 st = 154 lb; 13 st = 182 lb; 14 st = 196 lb; 200 lb ≈ 14.29 st (14 st 4 lb).
Assumptions and limitations
- One imperial stone equals exactly 14 avoirdupois pounds.
- Results are decimal stones; split the remainder into pounds by hand as shown above.
Frequently asked questions
How many pounds are in a stone?
Exactly 14 pounds.
Is 10.5 stone the same as 10 st 5 lb?
No. 10.5 st is 10 st 7 lb, because half a stone is 7 lb. 10 st 5 lb is 145 lb, or about 10.36 st.
Why is a stone 14 pounds?
Different trades once used stones of different sizes. The 14-pound stone became the standard in British law, and that is the value used everywhere today.
How do I get kilograms from stones and pounds?
Convert to total pounds first (stones × 14 + pounds), then multiply by 0.45359237. 10 st 7 lb is 147 lb, or about 66.68 kg.
How this calculator is checked
Method: Imperial definition: 1 st = 14 lb exactly. The calculation is covered by automated tests with known reference values and edge cases. Last updated 2026-10-18. Found a problem? Tell us.
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