Weight & Mass Converter
Convert between milligrams, grams, kilograms, tonnes, ounces, pounds, and stone instantly.
Enter a weight and select the unit to see conversions to all other weight units.
Conversions use exact avoirdupois definitions, including 1 pound = 0.45359237 kg and 1 ounce = 28.349523125 g.
Milligrams (mg)
1,000,000 mg
Grams (g)
1,000 g
Metric Tonnes (t)
0.001 t
Ounces (oz)
35.273962 oz
Pounds (lb)
2.204623 lb
Stone (st)
0.157473 st
Three Systems, One Planet
The metric system uses grams and kilograms. The imperial system uses ounces and pounds. And then there's stone, a unit the rest of the world finds baffling but the UK and Ireland refuse to give up. A British person's weight is in stone and pounds. Their food is sold in grams and kilograms. Their American relatives think in pounds. No wonder everyone needs a converter.
The key relationships are fixed definitions: 1 pound = 0.45359237 kg exactly, 1 ounce = 28.349523125 g exactly, and 1 stone = 14 pounds = 6.35029318 kg. Every other supported conversion builds on those values.
Conversion Quick Reference
| From | To | Multiply by | Example |
|---|---|---|---|
| Grams | Ounces | 0.03527 | 250 g = 8.82 oz |
| Ounces | Grams | 28.3495 | 8 oz = 226.8 g |
| Kilograms | Pounds | 2.2046 | 75 kg = 165.3 lbs |
| Pounds | Kilograms | 0.4536 | 150 lbs = 68.0 kg |
| Stone | Kilograms | 6.3503 | 11 st = 69.9 kg |
| Kilograms | Stone & lbs | ÷ 6.35 + remainder | 80 kg = 12 st 8 lbs |
| Metric tonnes | Pounds | 2,204.6 | 1 t = 2,204.6 lbs |
Mental maths shortcut: To convert kg to lbs, double the number and add 10%. So 70 kg → 140 + 14 = 154 lbs (exact: 154.3). To go from lbs to kg, halve the number and subtract 10%. 150 lbs → 75 - 7.5 = 67.5 kg (exact: 68.0).
Metric Weight Reference Table
Metric mass units scale by powers of ten. They are the everyday standard for food labels, medicine, science, shipping manifests, and most international product listings.
| Metric unit | Exact relationship | Common use |
|---|---|---|
| 1 milligram (mg) | 0.001 g | Supplements, small quantities, laboratory work |
| 1 gram (g) | 1,000 mg | Ingredients, parcels, small products |
| 1 kilogram (kg) | 1,000 g | Body weight, luggage, gym weights, food packaging |
| 1 metric tonne (t) | 1,000 kg | Vehicles, freight, bulk materials |
Imperial and Avoirdupois Reference Table
The ounce and pound values in this converter are avoirdupois units, the system used for food, parcels, luggage, and body weight. They are different from troy ounces used for precious metals.
| Imperial unit | Exact metric value | Exact imperial relationship |
|---|---|---|
| 1 ounce (oz) | 28.349523125 g | 1/16 pound |
| 1 pound (lb) | 0.45359237 kg | 16 ounces |
| 1 stone (st) | 6.35029318 kg | 14 pounds |
| 1 US short ton | 907.18474 kg | 2,000 pounds |
| 1 UK long ton | 1,016.0469088 kg | 2,240 pounds |
This page converts metric tonnes, not US short tons or UK long tons. If a shipment document says "ton", check the country and context before converting.
Body Weight by Unit System
Your doctor uses kg. Your gym uses lbs. Your nan asks in stone. Here's the same weight in all three:
| Stone & lbs | Pounds | Kilograms |
|---|---|---|
| 8 st 0 lbs | 112 lbs | 50.8 kg |
| 9 st 0 lbs | 126 lbs | 57.2 kg |
| 10 st 0 lbs | 140 lbs | 63.5 kg |
| 11 st 0 lbs | 154 lbs | 69.9 kg |
| 12 st 0 lbs | 168 lbs | 76.2 kg |
| 13 st 0 lbs | 182 lbs | 82.6 kg |
| 14 st 0 lbs | 196 lbs | 88.9 kg |
| 15 st 0 lbs | 210 lbs | 95.3 kg |
| 16 st 0 lbs | 224 lbs | 101.6 kg |
Practical Weight References
Numbers without context are meaningless. Here's what different weights actually feel like:
A medium apple. 3.5 oz. About the weight of a smartphone without a case.
A pack of mince from the supermarket. About 1.1 lbs. Roughly the weight of a hardback book.
A litre of water. 2.2 lbs. About the weight of a bag of sugar.
A bag of potatoes. 11 lbs. About the weight of two medium dumbbells.
Standard airline checked bag limit. 50.7 lbs. Roughly the weight of a car tyre.
Mass vs Weight: Does It Matter?
Technically, kilograms measure mass (the amount of stuff) and pounds measure force (how hard gravity pulls on that stuff). On Earth's surface, this distinction is irrelevant for everyday purposes, 1 kg always weighs 2.205 lbs.
It only matters in physics and engineering. On the Moon, a 75 kg person still has 75 kg of mass but would weigh only about 27.5 lbs instead of 165 lbs. For cooking, shipping, fitness, and everything else on this planet, kg and lbs are interchangeable via a fixed conversion factor.
Worked Example: Luggage Limit in Two Systems
Suppose Priya is flying from Toronto to London and her airline lists a checked bag limit as 50 lb, while her home scale shows kilograms.
Use the exact factor
1 lb = 0.45359237 kg
Multiply
50 × 0.45359237 = 22.6796185
Round sensibly
50 lb is about 22.7 kg
If the airline counter rounds to 23 kg, a 22.7 kg bag is normally within that limit. If the policy says exactly 50 lb, keep a little margin because scales vary.
Common Weight Conversion Mistakes
Using troy ounces for food
A regular ounce is 28.349523125 g. A troy ounce is about 31.1035 g and is used for gold, silver, and other precious metals.
Rounding every step
Convert with the exact factor first, then round the final answer. This matters for shipping, recipes, and repeated batch calculations.
Confusing tonne and ton
A metric tonne is 1,000 kg. A US short ton is 2,000 lb. A UK long ton is 2,240 lb. They are close enough to confuse, but not close enough to swap.
Writing stone as decimal pounds
11 st 6 lb is 160 lb, not 11.6 stone in ordinary notation. Convert stone to pounds first, then add the remaining pounds.
Assuming scale precision is accuracy
A bathroom scale may show one decimal place but still vary between readings. Do not treat a converted value as more exact than the original measurement.
Mixing mass and force in physics
Everyday conversions treat kg and lb as practical weight units. In engineering, mass, force, and local gravity need more careful handling.
Related Tools
How to use this tool
Enter the weight value you want to convert
Select the source unit from the dropdown
View instant conversions to all other weight units
Common uses
- Converting recipe ingredients between grams and ounces
- Calculating luggage weight limits in kg or lbs
- Converting body weight between imperial and metric
- Comparing product weights across international listings
- Checking shipping, gym, and supermarket weights across regions
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Frequently Asked Questions
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