1 Pound to Stones

One pound is 0.0714 of a stone, and the decimal never ends

One pound is 1/14 of a stone. Run that division and you get 0.0714285714, then the same six digits again, forever. Fourteen does not divide into any power of ten, so no calculator will ever print a clean answer for a single pound.

At three decimal places the small steps are easy to hold in your head: 1 lb is 0.071 st, 2 lb is 0.143 st, 3 lb is 0.214 st, 7 lb is exactly 0.500 st, 10 lb is 0.714 st, and 14 lb is 1.000 st. Those are the numbers a converter should return, and they are the numbers the calculator on this page returns.

Both definitions underneath are exact. A stone is 14 pounds, and an international avoirdupois pound is 0.45359237 kg, fixed by the 1959 yard and pound agreement and restated by NIST in Handbook 44 (2026 edition, Appendix B) and in SP 811 Appendix B.9, where the pound appears as 4.535 924 E-01 kg. Multiply the two and a stone is 6.35029318 kg, with no rounding anywhere.

The stone was not always one number. Wool merchants used a 14 lb stone in some towns and a heavier one in others, and London butchers worked with an 8 lb stone. Body weight settled on 14 lb, and the Weights and Measures Act 1985 writes the stone into law at 14 pounds, with the pound at 0.453 592 37 kg exactly.

The older imperial table stacked other weights on the stone. Two stone made a quarter, four quarters made a hundredweight of 112 lb, and 20 hundredweight made a long ton of 2,240 lb. Those units have left everyday use, but the arithmetic still checks out: a hundredweight is exactly 8 st and a long ton is exactly 160 st, which shows the 14 lb stone sitting inside a base-16 system rather than a decimal one.

Divide by 14, then keep the remainder as pounds

The two-step method behind x st y lb

A stone figure printed as a decimal is fine for a spreadsheet. A British scale, a gym log or a newspaper prints the whole stone and the leftover pounds instead, and the leftover is the part people get wrong.

Take the pounds, divide by 14, and drop everything after the decimal point. That is the stone count. Multiply the stone count back by 14 and subtract from the original weight. What is left is the pounds.

165 lb divided by 14 is 11.785714. Drop the decimal: 11 stone. Eleven times 14 is 154, and 165 minus 154 leaves 11. So 165 lb is 11 st 11 lb, or 11.786 st, or 74.8427 kg. The same run for 200 lb gives 14.285714, so 14 st and 4 lb left over. For 158 lb you get 11 st 4 lb, the reading a lot of adult men in the UK see on a Tuesday morning.

The tables below carry the same arithmetic for the weights that come up most often. Every row is pounds divided by 14 for the stone column, and pounds times 0.45359237 for the kilos.

One row is worth memorizing: 14 lb. It is the only entry where the stone column lands on a whole number and the pounds column lands on zero. If a converter tells you 14 lb is 0.98 st or 1.02 st, it is multiplying by something other than 1/14.

The kilogram behind the pound: 0.45359237

Why the kilo column is not an estimate

Most of the world weighs people in kilograms, and every UK hospital, GP surgery and pharmacy records both. The bridge is one number: 1 lb = 0.45359237 kg. NIST lists it as 4.535 924 E-01 in SP 811, and Handbook 44 Appendix B gives the full definition as 1 avoirdupois pound = 0.453 592 37 kilogram.

Working the other way, 1 kg is 2.2046226 lb, which is 0 st 2.2 lb, and 1 stone is 6.35029318 kg. So a person at 11 st 4 lb is 158 lb and 71.6676 kg. A 100 kg reading on a clinic scale is 220.4623 lb, which is 15 st 10.5 lb.

Kilogram readings are where rounding starts to bite. A scale that reports to 0.1 kg is reporting to about 0.22 lb, so it cannot show a one pound change at all. If you are tracking a pound a week, the kilo figure will look flat for two or three weeks and then jump.

Those rows come from dividing kilograms by 0.45359237. A 70 kg adult is 154.3 lb and reads as 11 st 0.3 lb, which is why a metric scale and a stone scale can disagree by a pound without either being broken.

What one pound looks like on a UK bathroom scale

Mechanical UK scales are marked in stones with tick marks for pounds, usually 14 ticks to the stone and a bolder mark at the half stone. Digital ones flip between a stone and pound reading and a kilogram reading with a small button, and the stone reading is written as 11:11 or 11 st 11 lb.

A dial with a 20 st face carries 280 one pound marks around the rim, and reading one of those at a glance is a skill in itself: the pointer sits somewhere between two ticks and the owner reports the nearer one. Digital scales removed the guesswork but introduced a new quirk, because many round the display to the nearest 0.2 lb and hold that number for a second before settling.

One pound is the smallest step those scales resolve, and it is roughly the weight of a large apple or a full can of soda. That matters for expectations: a good week of fat loss is 1 to 2 lb, which is 0.071 to 0.143 st, and a scale that rounds to the nearest half pound can hide the whole thing.

For a US reader the practical translation is simpler. A pound is a pound on both sides of the Atlantic; the stone is only a packaging of 14 of them. Nothing about the pound changes when a British page says 12 st 4 lb. It is 172 lb, and if you want kilos, 78.0179 kg.

Boxing, racing and the NHS: where Americans meet the stone

Three places in ordinary reading push a US reader into stone figures. Boxing coverage from the UK quotes heavyweights in stone, so a 200 lb fighter is announced as 14 st 4 lb. Horse racing weights are in stone too, and a 9 st claim is 126 lb on the card.

Racing cards add a layer that confuses newcomers: the weight a horse carries includes the jockey, the saddle and lead pads, so an 8 st 10 lb claim is 122 lb of jockey plus gear, and the trainer tops it up to the handicap weight with lead. Boxing works the same way in reverse. A cruiserweight limit of 200 lb is 14 st 4 lb, and a fighter who misses it by 3 lb is 3 lb or 0.214 st over, which is a fraction of a stone and still enough to cancel a title bout.

The third is health. NHS body mass index tools accept stone and pounds as an input option, and a GP letter may say a patient has lost 1 st 4 lb without ever using kilos. If you are checking a BMI figure from a UK source, convert to pounds first: 11 st 11 lb is 165 lb, and then the standard formula works in either unit system.

The legal side is narrower than most people assume. The UK sells goods by weight in grams and kilograms, and imperial units are allowed for trade only in a short list: draught beer and cider by the pint, milk in returnable containers, and precious metals by the troy ounce. The GOV.UK guidance on weights and measures spells that out. The stone survives because body weight is not a trade transaction.

Luggage limits, parcels and gym plates in pounds and stones

Three numbers that cover most cases

Airline cabin limits are written in kilos, and the common 23 kg limit is 50.7063 lb, or 3 st 8.7 lb. A 20 kg limit is 44.0925 lb, or 3 st 2.1 lb. The old 32 kg business class allowance is 70.5479 lb, which is 5 st 0.5 lb and lands just above the 70 lb mark many scales show as a hard stop.

Gym plates are the other place the two systems collide. A 45 lb plate is 3.214 st, and a pair is 6.429 st, so a bar loaded with four plates is 180 lb plus the 45 lb bar, which is 225 lb or 16 st 1 lb. That is why a strong lifter's total in kilos, 102.1 kg, looks unfamiliar next to the plate stack.

A hard-shell case weighs 9 to 11 lb empty, so a 50.7 lb allowance leaves about 40 lb for clothes, and a duffel that starts at 3 lb leaves 47. The airline counter scale reads kilos, the bathroom scale at home reads stones, and the sizer at the gate only cares whether the case fits the frame. Weigh the packed case on the bathroom scale, convert, and write the pound figure on a tag.

The bag rows are the useful ones. If your scale reads stones and the airline limit is kilos, convert the limit once and write it on the suitcase tag: 23 kg is 50.7 lb, so anything under 3 st 8 lb is safe.

Rounding: 0.07, 0.071 or 0.0714

Three decimal places is the practical choice. It keeps one pound at 0.071 st and 100 lb at 7.143 st, and the largest error you can introduce is half of 0.001 st, which is 0.014 lb or about a fifth of an ounce. Nobody weighing a person needs better than that.

Two places is where answers start to look wrong. At two places 1 lb rounds to 0.07 st, and 10 lb rounds to 0.71 st instead of 0.714 st, a 0.6 percent error. Across a 20 st range that is more than a pound of drift, which is enough to make a weight-loss log look inconsistent from week to week.

Whole percentages are useful for a sanity check. One pound is 7.14 percent of a stone, so a change of 4 lb is 28.6 percent of a stone, and a change of 7 lb is exactly half. If a number in a table does not sit near 7 percent of its pound value, the table is wrong.

One more trap: the stone is not metricated in conversation. Nobody says 0.5 st in a gym; they say half a stone, or 7 lb. The decimal form is a calculator output, not a spoken unit.

Five checks that catch a bad pound-to-stone answer

Run these before you trust any converter, including this one.

1. Fourteen pounds must give exactly 1.000 st. No exceptions, no 0.999.
2. A stone answer is always about 7 percent of the pound figure. 200 lb should land near 14, 50 lb near 3.6.
3. If the stone figure is 0, the weight is under 14 lb, and the pounds figure should match it one for one.
4. Multiply stones by 6.35029318, or pounds by 0.45359237. If the kilo column disagrees with the stone column by more than a rounding step, one of them is wrong.
5. Stones plus pounds must rebuild the original. 11 st 11 lb is 11 times 14 plus 11, which is 165.

The fifth check is the one that catches transcription errors, because it uses only integers. A reading of 11 st 14 lb is impossible and means the remainder was never carried into the stone count.