Weight & Mass Converter
Convert between any two kilogram units in your browser — instant, accurate, and private.
Example
1 t = 1,000 kg. Switch the unit menus to convert between any pair.
How it works
Every value is converted through a single kilogram base unit using internationally defined conversion factors, so any from/to pair stays consistent.
Good to know
Switching between metric and imperial weight units is one of the most common everyday conversions: a recipe from a British or European cookbook lists flour in grams while your scale reads ounces, a parcel courier quotes a limit in kilograms while your luggage scale shows pounds, and a US medical chart records body weight in pounds where the rest of the world uses kilograms. Because this tool spans ten units — from the microgram up to the metric tonne, US ton, and British long ton — it also covers science-lab quantities and freight-scale shipping weights in the same place.
The split comes down to two systems. Kilogram, gram, milligram, microgram, and tonne are metric (SI), each a clean power of ten apart. Pound, ounce, stone, US ton, and long ton are imperial/US customary, defined relative to the kilogram since 1959: one pound is exactly 0.45359237 kg, and an ounce is exactly 1/16 of that. Stone (14 lb) survives mainly for UK body weight, while the US ton is 2,000 lb and the British long ton is 2,240 lb — a 240-pound gap that trips up shipping paperwork.
For quick mental math, lean on these shortcuts:
- kg to lb: double it and add 10% (70 kg → 140 + 14 = 154 lb, actual 154.3).
- grams to ounces: divide by 28.35, or roughly multiply by 0.035.
- pounds to kg: halve it and shave off ~10% (150 lb → 75 − 7.5 ≈ 68 kg).
The most common mistake is confusing the three "tons": a metric tonne (1,000 kg) is about 2,205 lb, a US short ton is 2,000 lb (≈907 kg), and a long ton is 2,240 lb (≈1,016 kg) — never assume they're interchangeable. Also watch the milligram/microgram boundary in medication doses, where a factor of 1,000 separates them, and remember this tool measures mass, not weight-as-force, so results don't change with gravity or location.
Frequently asked questions
What does the weight & mass converter do?
It converts between common kilogram units instantly. Pick a unit to convert from and a unit to convert to, type a value, and the result updates live.
Which units does this converter support?
It includes 10 units: Tonne, Kilogram, Gram, Milligram, Microgram, Pound, Ounce, Stone, US ton, Long ton.
Is this converter free and private?
Yes. It runs entirely in your browser, so your inputs never leave your device, there is no sign-up, and it works offline once loaded.
Are the conversions exact?
Conversions use internationally defined factors and are exact where the definitions are exact (for example, 1 inch = 2.54 cm). Displayed results are rounded for readability.
People also ask
How many pounds are in a kilogram?
One kilogram equals about 2.20462 pounds. So 5 kg is roughly 11.02 lb, and a quick estimate is to double the kilograms and add 10%.
What is the difference between a tonne, a US ton, and a long ton?
A metric tonne is 1,000 kg (about 2,204.6 lb), a US short ton is 2,000 lb (about 907.2 kg), and a British long ton is 2,240 lb (about 1,016 kg). They are all different, so always confirm which 'ton' a quote refers to.
How many grams are in an ounce?
One ounce equals about 28.35 grams (exactly 28.3495 g). So 4 oz is roughly 113.4 g, close to a standard 113 g stick of butter.
How do I convert stone to pounds and kilograms?
One stone is exactly 14 pounds, which is about 6.35 kg. For example, 11 stone equals 154 lb or about 69.85 kg.
How many milligrams are in a gram?
One gram equals 1,000 milligrams, and one milligram equals 1,000 micrograms. So 0.5 g is 500 mg, and 2 mg is 2,000 mcg.
What does kg stand for and why is it the base unit here?
Kg stands for kilogram, the SI base unit of mass. This tool converts every value through the kilogram, so any from/to pair, like ounces to stone, stays consistent.
Is mass the same as weight?
In everyday use the terms are used interchangeably, but strictly mass (measured in kg or lb here) is the amount of matter and stays constant, while true weight is a force that varies with gravity. This converter handles mass, so your numbers are the same on Earth or the Moon.
How many ounces are in a pound?
One pound equals exactly 16 ounces. So 3 lb is 48 oz, and half a pound is 8 oz.
Related calculators