Weight Converter

Convert between kilograms, pounds, ounces, stones and tonnes — one value, or a pasted list.

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What this tool does

Weight Converter holds thirteen mass units against a kilogram base and multiplies by the defined factor rather than an approximation: a pound is 0.45359237 kg, a stone is fourteen of those, an ounce is a sixteenth of one, and a metric tonne is 1000 kg. The From and To lists carry microgram, milligram, gram, kilogram, tonne, ounce, pound, stone, US short ton, UK long ton, grain, carat and troy ounce, and setting To to All units (table) prints a single value against every one of them at once.

Input is read line by line, so a column pasted out of a spreadsheet is converted in one pass. A line may name its own units, and those override the two dropdowns for that line alone — 14 lb to st, 250 g to oz, 150 lbs to kg. Plurals and spelled-out names resolve, thousands separators in either convention are stripped, and fractions are understood, so 2½ lb and 1 1/2 st both parse. Each answer prints as a sentence and as a table row, with the factor for the last pair shown underneath so the arithmetic can be checked by hand. All of it is JavaScript in the page: no figure you type is sent anywhere or written to a log, and a tab that is already open keeps converting after the connection drops — there is no offline cache behind that, so the page itself still has to be fetched while you are online.

Three limits decide whether this is the right page. It knows mass and nothing else, so a line reading 5 ft or 1 cup is refused with an error listing the units it does recognise — grams to cups needs the density of the specific ingredient, which is what Cooking Converter is for, and there are no force units here, so kilograms will not become newtons. Two spellings resolve in ways worth knowing before you trust a number: a bare ton is the US short ton of 907.18474 kg, not the metric tonne and not the UK long ton, and gr is the grain, so 500 gr comes back as 32.4 g rather than half a kilo. And compound imperial weights work in neither direction — 9 st 4 lb is rejected as a unit it cannot read, and a conversion into stones returns 9.285714286 st instead of splitting the remainder off into pounds.

How to use it

  1. Type a value, or paste a column of them. One per line. Load sample fills the box with 1, 14 lb to st and 250 g to oz, which covers the three shapes a line can take.
  2. Choose the units, or name them in the line. The lists open on kilograms and pounds. A unit written after the number wins for that line, and a target after the word to overrides the To list.
  3. Switch To to All units (table) when the target is not fixed. One value is then printed against all thirteen units together, in the order the dropdowns list them — microgram first, troy ounce last — which is quicker than converting four times.
  4. Set the precision. Automatic shows up to ten significant digits and drops to exponential notation for very large or very small results. The fixed choices are 0, 1, 2, 3, 4, 6 and 8 decimals.
  5. Read the sentence, the table row or the factor. Each converted line becomes one row beside the plain-text output, and the factor for the last pair is printed at the end. The all-units table is the exception: it returns thirteen rows for every line and no factor line.

Processing & privacy

Runs on your device. Your file is processed directly in this browser.

Common use cases

A body weight quoted in stones

UK health forms ask for stones while gym equipment abroad reads kilograms. Typing 11 st to kg settles it without a mental sum in fourteens.

Filling in a courier or customs declaration

The parcel scale reads kilograms and the form wants pounds. Two decimals matches what most shipping forms will accept in the field.

Following a recipe written in ounces

250 g to oz turns the supermarket packet into the figure the recipe assumes, provided the ingredient is weighed rather than measured by volume.

Pricing scrap metal or bullion

A troy ounce is 31.1034768 g and an ordinary ounce is 28.35 g — roughly a ten per cent gap, which matters as soon as a price per ounce is attached.

Converting a whole column of package weights

Paste the column and every row is converted in a single pass, rather than retyping each figure into a search box one at a time.

Questions

Are the numbers I type uploaded?
No. The conversion is JavaScript running in this browser tab, so the values stay on your own machine and no figure you type is transmitted or logged. The page itself does count an anonymous visit for this tool once per session, and it caches nothing for offline use, so open it while you are connected.
How many kilograms is a pound?
0.45359237 kg exactly — the international avoirdupois pound agreed in 1959, and the factor every result here is built on. In the other direction 1 kg is 2.204622622 lb.
Can I type 9 st 4 lb?
No. A line takes one number and one unit, so that is refused as an unrecognised unit. Enter 130 lb instead, and expect one decimal figure back — 9.285714286 st, or 9.29 st at two decimals — rather than a stones-and-pounds pair.
Does ton mean the metric tonne?
Not here. A bare ton resolves to the US short ton of 907.18474 kg. Write t or tonne for the metric tonne of 1000 kg, and UK ton for the long ton of 1016.0469088 kg.
Why did 500 gr come out as 32.4 grams?
Because gr is the symbol for the grain, 64.79891 mg, and an exact symbol match is preferred over an alias. Capitalisation quietly settles it as well — a typed GR misses that symbol and falls back to grams — so write 500 g or 500 grams when grams are what you mean.
Can it convert grams to millilitres or cups?
No. That crosses from mass into volume and needs the density of whatever is being measured, since water, flour and honey all differ. Cooking Converter covers the common ingredients.
Is the ounce here a troy ounce?
No. Ounce means the avoirdupois ounce of 28.349523125 g, the one used for food and post. The troy ounce is a separate entry in both lists at 31.1034768 g.

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