Weight Converter
Convert weight between milligrams, grams, kilograms, metric tons, ounces, pounds, and stone.
How to use this tool
- Enter weight and from unit in the fields above.
- Results update instantly as you type — or click Calculate.
- Read your pounds and the full breakdown beneath it.
Formula
All units convert to grams first, then to the target unit:
grams = input × factorfrom
output = grams ÷ factorto
Key factors: mg = 0.001 g | g = 1 g | kg = 1000 g | metric ton = 1,000,000 g | oz = 28.3495 g | lb = 453.592 g | stone = 6350.293 g
How it works
The converter normalises every weight to grams as the base unit, then divides by the gram-equivalent of each output unit. This single-pivot approach avoids maintaining a large matrix of direct conversion factors between every possible unit pair.
A common mistake is confusing mass and weight: in everyday usage these terms are used interchangeably, but scientifically, weight is a force (measured in newtons) while mass (kilograms, pounds) is the quantity of matter. This calculator converts units of mass, not force. Additionally, the troy ounce (used for precious metals, 31.10 g) is different from the avoirdupois ounce (28.35 g) used here — mixing them up leads to significant errors in jewellery and commodities contexts.
Worked example
Convert 1 kilogram to all weight units
- Input: 1 kilogram (from_unit = kilogram), so base in grams = 1 × 1000 = 1000 g.
- Milligrams: 1000 / 0.001 = 1,000,000 mg. Grams: 1000 / 1 = 1000 g. Metric tons: 1000 / 1,000,000 = 0.001 t.
- Ounces: 1000 / 28.3495 ≈ 35.274 oz. Pounds: 1000 / 453.592 ≈ 2.2046 lb.
- Stone: 1000 / 6350.293 ≈ 0.1575 st.
1,000,000 mg | 1000 g | 1 kg | 0.001 t | 35.274 oz | 2.2046 lb | 0.1575 st
Common mistakes to avoid
- Confusing mass and weight -- this converter handles mass; weight in newtons requires multiplying mass by gravitational acceleration (9.80665 m/s2).
- Forgetting that a UK/imperial ton (long ton, 2,240 lb) and a US ton (short ton, 2,000 lb) are different from a metric ton (1,000 kg = 2,204.6 lb).
- Entering stone without accounting for the stone+pounds format -- 11 stone 4 pounds is 11.286 stone, not 11.4.
Key terms
- Kilogram (kg)
- The SI base unit of mass, equal to 1000 grams. Defined by the Planck constant since 2019.
- Pound (lb)
- An imperial unit of mass equal to exactly 453.59237 grams, used primarily in the US and UK.
- Stone (st)
- A British unit of body weight equal to 14 pounds (approximately 6.35 kg), still commonly used in the UK for personal weight.
- Metric ton (t)
- Equal to 1000 kilograms or 1,000,000 grams. Also called a tonne. Not the same as the US short ton (907 kg) or British long ton (1016 kg).
Frequently asked questions
- How many pounds are in a kilogram?
- One kilogram equals approximately 2.20462 pounds. Conversely, one pound is about 0.45359 kg.
- What is the difference between a metric ton, a short ton, and a long ton?
- A metric ton (tonne) is exactly 1,000 kg. A US short ton is 2,000 lb (about 907.2 kg). A UK long ton is 2,240 lb (about 1,016 kg). Always confirm which ton is meant in international shipping contexts.
- How do I convert milligrams to grams?
- Divide by 1,000. For example, 500 mg = 0.5 g. The converter handles this automatically, but the mental shortcut is useful for quick medication dosage checks.