Weight Converter
Convert between weight units
How It Works
Overview
A weight converter translates a value from one unit of mass to several others at once. Enter a number and a starting unit, and you'll instantly see the equivalent in kilograms, grams, milligrams, metric tons, pounds, ounces, stones, and US (short) tons. It's the fastest way to bridge between metric and imperial systems without doing the arithmetic by hand.
Strictly, the units here measure mass — the amount of matter in an object — but in everyday speech they're often called "weight" because a household scale calibrated to standard Earth gravity reports them interchangeably. True weight is a force (Newtons or pounds-force) and depends on local gravity; mass does not. This tool handles unit conversion only, not the gravitational calculation.
The Formula
Internally, every unit is converted to kilograms first, then to the target. Key conversion factors used here:
- 1 kg = 1,000 g = 1,000,000 mg
- 1 metric ton = 1,000 kg
- 1 lb ≈ 0.453592 kg (so 1 kg ≈ 2.20462 lb)
- 1 oz ≈ 0.0283495 kg (16 oz = 1 lb)
- 1 stone = 14 lb ≈ 6.35029 kg
- 1 US ton = 2,000 lb ≈ 907.185 kg
Worked Example
Suppose a recipe calls for 750 g of flour and you only have a scale measuring in ounces. Converting 750 g (= 0.750 kg):
- Pounds: 0.750 ÷ 0.453592 ≈ 1.653 lb
- Ounces: 0.750 ÷ 0.0283495 ≈ 26.46 oz
Another example: a shipping label lists 2.5 US tons. Converting: 2.5 × 907.185 = 2,267.96 kg = 2.268 metric tons = about 5,000 lb. That last figure follows directly from the definition of a US ton (2,000 lb) — useful for sanity-checking shipping paperwork.
When to Use This
- Cooking and baking — converting recipes between metric (grams, kilograms) and imperial (ounces, pounds).
- Fitness and health — switching body weight between kg and lb (or stone for UK contexts).
- Shipping and freight — comparing US tons, metric tons (tonnes), and kilograms on bills of lading.
- Lab and pharmacy work — handling milligrams, grams, and ounces in dosing or mixing.
- International commerce — converting product weights for cross-border listings and customs forms.
Common Mistakes to Avoid
- Mixing up tons. A US (short) ton is 907 kg, a metric ton is 1,000 kg, and a UK (long) ton is 1,016 kg — never assume which is meant.
- Confusing standard ounces with troy ounces. Precious metals use troy ounces (31.1 g), not the regular 28.35 g ounce most other goods use.
- Treating weight on the Moon the same as on Earth. Mass is the same, but a bathroom scale would read about one-sixth on the Moon.
- Rounding too early. If you need precision (medical, scientific), keep extra decimals during conversion and round only at the end.
- Forgetting the 1 kg ≈ 2.2 lb shortcut is approximate. The exact factor is 2.20462 — close enough for everyday use, but check more carefully for shipping or compliance limits.
Frequently Asked Questions
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