Weight Converter

How to Convert a Weight

Features

Three Tons, One Word

Order "10 tons" of steel and the number you actually receive depends entirely on which country wrote the contract. A metric tonne is 1,000 kg. A US short ton is 907.18474 kg. A UK long ton is 1,016.0469088 kg. Ten of the lightest against ten of the heaviest is a swing of nearly 1,090 kilograms — nowhere near a rounding error on a freight invoice or a commodity contract. All three trace back to the same historical mess: the short ton comes from 2,000 avoirdupois pounds, the long ton from 2,240, and the metric tonne simply from the kilogram, and nothing about the word "ton" on its own tells you which, and a contract that just says "ton" without specifying is quietly ambiguous the moment it crosses a border — a mining company quoting reserves in metric tonnes to European investors and US short tons to American ones is not being dishonest, just following two separate reporting conventions that happen to use the same English word. This converter treats all three as separate, named units rather than one, which turns out to be the single most useful thing it does for anyone in freight, mining, or bulk trade — the live table below lists all twelve supported units against whatever value you type, and the Imperial & US filter chip puts the two competing tons side by side so a mismatch is visible at a glance instead of buried in a spreadsheet column.

Carat, Karat — Same Sound, Nothing Alike

A jeweller will use both words in the same breath about the same ring, and they are not talking about the same thing. A carat is a unit of weight, fixed at exactly 200 milligrams — a 2-carat diamond weighs 400 mg wherever in the world you buy it. A karat is a purity scale for gold, measured in 24ths, with no connection to weight at all: 18-karat gold is 75% pure gold by mass, regardless of whether the piece weighs one gram or one hundred. Confuse them and a "2 ct, 18k" listing turns into nonsense. This tool only handles the first one — carats convert cleanly against grams, ounces, and every other mass unit here, while karat purity is a different kind of number entirely and has no conversion factor to speak of. Grains cause a smaller version of the same mix-up in a completely different world — ammunition reloaders and archers measure bullet weights and arrow spine in grains, about 64.8 mg each, a unit that has nothing to do with cereal grain and everything to do with a barleycorn-based system older than either the metric or imperial one it now quietly sits inside. Grains have an odder cousin, too: the old apothecary system used by pharmacists before metrication defined its own dram and ounce, built out of grains at a different ratio to the everyday avoirdupois ounce this converter uses — an apothecary ounce is roughly 10% heavier than an avoirdupois one, a discrepancy that quietly disappeared from most prescriptions only once pharmacies switched to metric dosing in grams and millilitres.

A Butter Weight, an Invoice, and a Dosage

A French pastry recipe calls for 250 g of butter and the kitchen scale only shows ounces — 8.82 oz, and the recipe proceeds without a mental-math detour. A supplier logs a shipment at 2,450 lb, but the freight quote is priced per kilogram; converting first gives 1,111.30 kg, a number worth checking against the invoice before it is signed off rather than after a dispute starts. A compounding pharmacist double-checking a dosage moves between milligrams and micrograms, where the difference between the two is not a rounding preference but a decimal point that matters for patient safety — exactly the kind of precision this converter was built to never fumble. And in a gym halfway between those two extremes, someone loading a barbell with 20 kg plates checks what that comes to in the 45 lb-plate world of a US programme, so the numbers on both sides of an online lifting log actually line up. A step further still, someone posting a parcel checks it against a courier's weight bands — often quoted in kilograms for a domestic shipment but pounds and ounces for an international one — because crossing a single band boundary by a few grams can bump the shipping cost into the next price tier entirely. For the volume side of that pastry recipe, the Volume Converter covers cups, millilitres, and tablespoons.

The Stone-and-Pounds Problem

Kilograms run the rest of the world, pounds run American shopping and gym culture, and stone — fourteen pounds to the stone — refuses to disappear from British and Irish conversation about body weight even among people who use metric for everything else; UK medical forms routinely ask for both. The cheat sheet built into this converter answers that directly, listing common body weights in kilograms alongside decimal pounds and the combined "11 st 4 lb" format those forms actually expect, so nobody has to do the division by fourteen themselves. The same Precision control that handles that also scales up: Auto keeps everyday numbers readable and only drops into scientific notation for something like a microgram dose expressed in long tons, while a fixed 2, 4, 6, or 8 decimal-place setting is there for pharmacy, customs, or engineering paperwork that needs one exact format throughout.

None of these units are, strictly, weight at all — a physicist would call kilograms and pounds mass, and reserve "weight" for the force gravity exerts on that mass, measured in newtons. A 70 kg astronaut has exactly the same mass on the Moon as on Earth but would register roughly six times lighter on a scale there, because the mass stayed put while the gravity underneath it changed. Every unit in this converter is mass, which is what "weight" means in ordinary usage anyway — the distinction only actually matters if newtons show up somewhere in the problem, which for the vast majority of the people using this tool is never. A luggage scale at check-in, a kitchen scale, a set of gym plates, and a pharmacy balance are all, technically, measuring the same physical quantity everywhere on Earth, which is exactly why the distinction can be safely ignored outside a physics classroom.

What This Scale Won't Tell You

This is a mass converter, not a volume one — a cup of flour and a cup of honey weigh very different amounts, so recipe volumes belong on the Cooking Measurement Converter, not here. It also has nothing to say about gravitational force in newtons, a genuinely different physical quantity from every unit on this page. Nothing typed here is sent anywhere: the arithmetic runs entirely as JavaScript inside the browser tab, with no server call and nothing logged, which matters for patient body-weight records or a confidential cargo manifest. And for anything with legal, medical, or financial weight behind it — pharmaceutical dosing, customs declarations, commodity contracts — treat the result as a fast, accurate conversion of a figure you already trust, not a substitute for the original document it came from, and the tool keeps working identically with no internet connection at all once the page has loaded. Measuring height alongside weight is a job for the Length Converter.