Weight Conversion: kg to lbs, g to oz Guide
Weight conversion between metric and imperial systems is a constant need for travelers, cooks, athletes, and anyone who shops or communicates across international borders. The metric system uses grams and kilograms; the imperial and US customary system uses ounces, pounds, and stones. Converting accurately between these systems matters for medication dosages, luggage weight limits, recipe scaling, and fitness tracking. This guide covers every common weight conversion with exact formulas, a practical reference table, and real-world examples.
Weight Units: Metric vs Imperial
The metric weight units are built on the gram as the base unit, with the kilogram being 1,000 grams and the metric ton being 1,000 kilograms. Metric weight units from smallest to largest: Micrograms (mcg) — 1/1,000,000 gram. Used for vitamins, hormones, and medications. Milligram (mg) — 1/1,000 gram. Used for many medications and food nutrients. Gram (g) — the base metric weight unit. Kilogram (kg) — 1,000 grams. The standard unit for body weight outside the US. Metric ton (t) — 1,000 kg. Used for large masses, commodities, shipping. Imperial/US customary weight units: Ounce (oz) — the smallest common imperial weight unit. Pound (lb) — 16 ounces. The standard unit for body weight in the US. Stone (st) — 14 pounds = 6.35 kg. Used for body weight in the UK and Ireland. Short ton (US ton) — 2,000 pounds = 907.185 kg. Long ton (UK ton) — 2,240 pounds = 1,016.05 kg. Troy ounce — a separate unit used for precious metals. 1 troy ounce = 31.1035 grams, heavier than an avoirdupois ounce (28.3495 grams). When gold prices are quoted per ounce, it is always troy ounces.
Exact Conversion Factors: kg, lbs, oz, g
These conversion factors are based on the exact international definitions: 1 pound = 453.59237 grams (exact international definition) 1 pound = 0.45359237 kg 1 ounce = 28.349523125 grams 1 stone = 14 pounds = 6.35029 kg Reverse: 1 gram = 0.035274 ounces 1 gram = 0.0022046 pounds 1 kilogram = 2.20462 pounds 1 kilogram = 35.274 ounces 1 kilogram = 0.157473 stones Conversion formulas: Kilograms to pounds: multiply by 2.20462 Pounds to kilograms: multiply by 0.453592 (or divide by 2.20462) Grams to ounces: multiply by 0.035274 Ounces to grams: multiply by 28.3495 Quick calculation shortcuts: To convert kg to lbs roughly: multiply by 2.2 To convert lbs to kg roughly: divide by 2.2
Practical Weight Conversions: Body Weight, Food, and Luggage
Body weight is the most common personal weight conversion need. In the US, body weight is measured in pounds. In the UK, stones and pounds are traditional. Everywhere else, kilograms are standard. Body weight reference table: 50 kg = 110.2 lbs = 7 st 12 lbs 60 kg = 132.3 lbs = 9 st 6 lbs 70 kg = 154.3 lbs = 11 st 0 lbs 80 kg = 176.4 lbs = 12 st 8 lbs 90 kg = 198.4 lbs = 14 st 2 lbs 100 kg = 220.5 lbs = 15 st 10 lbs Food weight conversions for cooking: 100 g is approximately 3.5 oz 250 g is approximately 8.8 oz 500 g is approximately 17.6 oz = 1.1 lbs 1 kg is approximately 2.2 lbs Common ingredient weights per US cup: 1 cup all-purpose flour = approximately 120-130 g 1 cup granulated sugar = approximately 200 g 1 cup butter = 227 g = 8 oz = 1/2 lb Luggage weight limits: Most international airlines: checked bag limit 23 kg = 50.7 lbs US domestic flights: checked bag limit often 50 lbs = 22.7 kg Budget airline carry-on: 7-10 kg = 15.4-22 lbs
Weight vs Mass: The Technical Distinction
In everyday language, weight and mass are used interchangeably. In physics, they are different things. Mass is the amount of matter in an object. It is the same everywhere in the universe. The kilogram is the SI unit of mass. Weight is the force exerted on a mass by gravity. Weight = mass x gravitational acceleration. On Earth, gravitational acceleration is approximately 9.81 meters per second squared. On the Moon, gravity is about 1/6 of Earth's, so a 70 kg person weighs much less on the Moon — but their mass is still 70 kg everywhere. In everyday use, when a scale reads 70 kg, it is technically measuring the gravitational force and displaying it as a mass in kilograms by assuming standard Earth gravity. For everyday conversion purposes — body weight, food, luggage, parcels — the practical units are grams, kilograms, ounces, and pounds, and the WikiPlus Unit Converter handles all of these correctly.
Frequently Asked Questions
- How many pounds is 1 kilogram?
- 1 kilogram is exactly 2.20462 pounds. For a quick estimate, 1 kg is approximately 2.2 pounds. To convert any number of kilograms to pounds, multiply by 2.20462. For example, 10 kg = 22.046 pounds, 75 kg = 165.3 pounds. To convert pounds to kilograms, divide by 2.20462 or multiply by 0.453592.
- What is the difference between a pound and an ounce?
- There are 16 ounces in 1 pound. 1 pound = 453.592 grams. 1 ounce = 28.3495 grams. The ounce is the smaller unit — 16 times smaller than a pound. Note that the troy ounce used for precious metals is 31.1035 grams, heavier than the avoirdupois ounce, and there are 12 troy ounces in a troy pound.
- How many kilograms is one stone?
- 1 stone = 14 pounds = 6.35029 kilograms. The stone is used primarily in the United Kingdom and Ireland for expressing human body weight. To convert stones to kilograms, multiply by 6.35029. To convert kilograms to stones, divide by 6.35029.