Weight Converters
Convert weight and mass between kilograms, pounds, ounces, grams, stones, and tons. Essential for cooking, shipping, fitness tracking, and international trade. See also our KG to LBS, Grams to Ounces, and Pounds to Stone converters.
Value:
Popular Weight Converters:
What is a Weight Converter?
A weight converter is a tool that converts measurements between different units of mass and weight such as kilograms, pounds, ounces, grams, and tons. It is widely used in cooking, shipping, fitness, science, and international trade where different weight systems are standard.
History of Weight Measurement
Weight measurement originated with the beam balance in ancient Egypt and Mesopotamia around 3000 BCE. The pound has roots in the Roman libra, while the kilogram was defined during the French Revolution as the mass of one liter of water. In 2019, the kilogram was redefined based on the Planck constant, making it the last SI base unit freed from a physical artifact.
About This Weight Converter
This weight converter supports over 60 units including kilograms, grams, milligrams, pounds, ounces, metric tons, short tons, long tons, stone, carats, grains, slugs, and atomic mass units. It handles metric, imperial, and US customary weight systems with high precision.
Understanding Weight and Mass Measurement
Weight and mass are closely related but technically different quantities. Mass measures the amount of matter in an object (kilograms in SI), while weight is the gravitational force on that mass (newtons in SI). However, in everyday language and most conversion contexts, "weight" refers to mass — how heavy something is. When you step on a bathroom scale showing 70 kg or 154 lbs, you are measuring mass, even though the scale actually responds to gravitational force.
Two primary systems dominate weight measurement worldwide. The metric system uses the kilogram as its base unit, with grams, milligrams, and metric tonnes for smaller and larger quantities. The imperial/US customary system uses the pound (lb) as its everyday unit, with ounces for smaller quantities and stones (UK) or short tons (US) for larger ones. The international avoirdupois pound is defined as exactly 0.45359237 kilograms.
Weight conversion is among the most common daily calculations globally. Cooks convert between grams and ounces, travelers check baggage limits in kg or lbs, doctors calculate drug doses based on patient weight, and international commerce requires constant conversion between metric and imperial mass units.
How to Convert Between Weight Units (Step-by-Step)
Weight conversion uses the same multiplication-by-a-factor method as other unit conversions. The kilogram serves as the best bridge unit between metric and imperial systems.
- Identify your source unit and target unit (e.g., pounds to kilograms).
- Find the conversion factor. The key bridge: 1 pound = 0.45359237 kg (exact).
- Multiply your value by the conversion factor: e.g., 150 lbs × 0.45359237 = 68.04 kg.
- For multi-step conversions, chain factors: e.g., stones to grams = stones × 14 (to get lbs) × 453.592 (to get grams).
- Sanity check: 1 kg ≈ 2.2 lbs, so 68 kg × 2.2 ≈ 150 lbs. The rough check confirms your answer.
Essential Weight/Mass Conversion Formulas
These are the most commonly needed weight conversion relationships, with exact factors where applicable:
- 1 kilogram (kg) = 2.20462 pounds (lb)
- 1 pound (lb) = 0.453592 kilograms (exact: 0.45359237 kg)
- 1 ounce (oz) = 28.3495 grams
- 1 gram (g) = 0.035274 ounces
- 1 stone = 14 pounds = 6.35029 kg
- 1 metric tonne = 1,000 kg = 2,204.62 lbs
- 1 short ton (US) = 2,000 lbs = 907.185 kg
- 1 long ton (UK) = 2,240 lbs = 1,016.05 kg
Worked Examples — Weight Conversions
Example 1: A recipe calls for 250 grams of flour. How many ounces is that?
Solution:
1 gram = 0.035274 ounces.
Multiply: 250 × 0.035274 = 8.82 ounces.
Alternatively: 1 ounce = 28.3495 g, so 250 ÷ 28.3495 = 8.82 oz.
Answer: 250 grams = 8.82 ounces (approximately 8⅞ oz).
Example 2: A person weighs 12 stone 7 pounds. What is their weight in kilograms?
Solution:
Convert stones to pounds: 12 × 14 = 168 lbs.
Add remaining pounds: 168 + 7 = 175 lbs total.
Convert to kg: 175 × 0.453592 = 79.38 kg.
Answer: 12 stone 7 lbs = 79.4 kg.
Example 3: An airline allows 23 kg checked baggage. How many pounds is that?
Solution:
1 kg = 2.20462 lbs.
Multiply: 23 × 2.20462 = 50.7 lbs.
Answer: 23 kg = 50.7 lbs (most airlines round to 50 lbs for simplicity).
Example 4: A shipment weighs 4.5 metric tonnes. Express in short tons (US) and long tons (UK).
Solution:
4.5 metric tonnes = 4,500 kg.
Short tons: 4,500 ÷ 907.185 = 4.96 short tons.
Long tons: 4,500 ÷ 1,016.05 = 4.43 long tons.
Answer: 4.5 metric tonnes = 4.96 short tons (US) = 4.43 long tons (UK).
Example 5: A medication dosage is 5 mg/kg body weight. What dose for a 154-pound patient?
Solution:
Convert patient weight to kg: 154 × 0.453592 = 69.85 kg.
Calculate dose: 69.85 × 5 mg/kg = 349.3 mg.
Answer: For a 154-lb patient at 5 mg/kg, the dose is 349 mg.
Quick Reference — Common Weight Conversions
The most frequently needed weight/mass conversion pairs at a glance.
| From | To |
|---|---|
| 1 kilogram | 2.20462 lbs |
| 1 pound | 453.592 g |
| 1 ounce | 28.3495 g |
| 1 gram | 0.03527 oz |
| 1 milligram | 0.001 g |
| 1 microgram (μg) | 0.001 mg |
| 1 stone | 6.350 kg |
| 1 metric tonne | 2,204.6 lbs |
| 1 short ton | 907.2 kg |
| 1 long ton | 1,016.0 kg |
| 1 carat | 200 mg |
| 1 troy ounce | 31.1035 g |
| 1 grain | 64.799 mg |
| 1 quintal | 100 kg |
Metric, Imperial, and Other Weight Systems
The metric system of mass centers on the kilogram, the only SI base unit still defined by a physical artifact until 2019 (when it was redefined via the Planck constant). The gram (1/1000 of a kg) is the practical small unit, with milligrams and micrograms for pharmaceuticals and chemistry. The metric tonne (1,000 kg) serves for large quantities. The elegance of the metric system is that volume and mass connect directly: 1 liter of water at 4°C has a mass of exactly 1 kilogram.
The avoirdupois system (from Old French "goods of weight") is the standard imperial weight system for everyday use. Its base unit is the pound (lb), divided into 16 ounces. The UK uniquely uses the stone (14 lbs) for body weight. The short ton (2,000 lbs) is standard in the US, while the UK historically used the long ton (2,240 lbs). Confusingly, a separate troy system exists for precious metals: 1 troy ounce = 31.1 g (heavier than the avoirdupois ounce of 28.35 g).
Other specialized weight systems persist in specific contexts. Carats (200 mg exactly) are used for gemstones. Grains (64.8 mg) appear in ammunition and pharmaceutical contexts. The Chinese jīn (500 g) and Indian seer (approximately 933 g, varying by region) are still used in local commerce. Understanding these niche units matters for international trade in specific commodities.
Where Weight Conversion Matters
Cooking & Baking
Recipes from different countries use grams or ounces. Precision baking requires accurate conversion — 1 cup of flour is approximately 125g, but this varies by measurement technique. Professional bakers weigh in grams for consistency.
Healthcare & Pharmaceuticals
Drug doses are calculated per kilogram of body weight. A nurse must convert a patient's weight from pounds to kg before calculating medication. Errors in weight conversion directly affect patient safety.
International Shipping
Cargo weight determines shipping costs and must match customs declarations. Containers have weight limits in both kg and lbs. A 20-ft container typically has a max payload of 21,700 kg (47,840 lbs).
Fitness & Nutrition
Gym weights may be in kg (Olympic) or lbs (US standard). Nutrition labels show serving sizes in grams. Body weight tracking requires consistent units — switching between kg and lbs without conversion causes confusion.
Precious Metals & Jewelry
Gold and silver are traded in troy ounces (31.1 g), not avoirdupois ounces (28.35 g). A "gold ounce" is about 10% heavier than a grocery store ounce. Diamonds use carats (200 mg).
Agriculture & Food Industry
Grain is traded in bushels (weight varies by crop), metric tonnes, or short tons. A farmer selling wheat internationally must convert between bushels, tonnes, and pounds for different markets.
Mass vs Weight: The Scientific Distinction
In physics, mass and weight are different quantities. Mass (measured in kg) is the amount of matter in an object — it stays the same everywhere in the universe. Weight (measured in newtons) is the gravitational force on that mass — it changes depending on local gravity. On the Moon (gravity ≈ 1.62 m/s²), a 70 kg person still has 70 kg mass but weighs only 113.4 N (compared to 686.7 N on Earth). In everyday life and unit conversion, we use "weight" to mean mass, and scales are calibrated for Earth's gravity. This works fine on Earth but matters for aerospace and physics applications.
Common Mistakes in Weight Conversion
The most frequent error is confusing ounces. There are fluid ounces (volume) and weight ounces (mass) — they are not the same unit. 1 fluid ounce of water happens to weigh approximately 1 oz, but this does not hold for other liquids. Another common mistake is using the wrong "ton" — a metric tonne is 10% heavier than a US short ton but 1.5% lighter than a UK long ton. Finally, people often confuse the carat (gemstone weight, 200 mg) with the karat (gold purity, 1/24th). 24-karat gold is pure gold; a 2-carat diamond weighs 400 mg.
Key Takeaways
- The kilogram is the SI base unit of mass. 1 kg = 2.205 lbs (approximately).
- The exact definition: 1 lb = 0.45359237 kg. All other conversions derive from this.
- There are three different "tons": metric tonne (1,000 kg), short ton (907 kg), long ton (1,016 kg).
- Troy ounces (precious metals) ≠ avoirdupois ounces (everyday). Troy oz is about 10% heavier.
- For quick estimates: double kg and add 10% to get lbs. Halve lbs and subtract 10% to get kg.
- In scientific contexts, distinguish mass (kg, inherent property) from weight (newtons, force due to gravity).
Metric Conversion Factor Tables for Weight Converter
| Units to convert | Multiply By The Number | Convert as Unit |
|---|---|---|
| Grains (gr) | 0.0648 | Grams (g) |
| Grams (g) | 0.002205 | Pounds (lbs) |
| Metric Tons (t) | 0.9842 | Tons (long 2240lb) |
| Metric Tons (t) | 1.1023 | Tons (short 2000lb) |
| Grains (gr) | 0.0000648 | Kilograms (kg) |
| Grams (g) | 15.4324 | Grains (gr) |
| Pounds (lbs) | 0.4535925 | Kilograms (kg) |
| Tons (long 2240lb) | 1.016 | Metric Tons (t) |
| Tons (short 2000lb) | 907.1848 | Kilograms (kg) |
| Tons (short 2000lb) | 0.9072 | Metric Tons (t) |
| Ounce (oz) | 28.35 | Grams (g) |
| Pounds (lbs) | 453.592 | Grams (g) |
| Ton | 907.185 | Kilograms (kg) |
| Long Ton | 1016.047 | Kilograms (kg) |
Weightconverters & it's abbreviations
| Unit | Abbreviation | Unit | Abbreviation | Unit | Abbreviation |
|---|---|---|---|---|---|
| Kilogram | kg | Gram | g | Milligram | mg |
| Metric Ton | t | Pound | lbs | Ounce | oz |
| Carat | car, ct | Short Ton (US) | ton | Long Ton (UK) | ton |
| Atomic Mass Unit | Da, u | Stone (UK) | st | Grain | gr |
| Pennyweight | pwt | Slug | slug | Hundredweight (US) | cwt |
| Hundredweight (UK) | cwt | Microgram | µg | Nanogram | ng |
Frequently Asked Questions
How many pounds are in a kilogram?
There are approximately 2.20462 pounds in one kilogram. To convert kg to lbs, multiply the kilogram value by 2.20462.
What is the difference between mass and weight?
Mass is the amount of matter in an object (measured in kilograms), while weight is the force of gravity on that mass (measured in newtons). In everyday use, the terms are used interchangeably.
How many grams are in an ounce?
There are approximately 28.3495 grams in one ounce (avoirdupois). For troy ounces used in precious metals, one troy ounce equals 31.1035 grams.
How do I convert stones to pounds?
Multiply the number of stones by 14 to get pounds. For example, 10 stone = 140 pounds. The stone is commonly used in the UK and Ireland for body weight.
What is the difference between a short ton and a metric ton?
A short ton (US ton) equals 2,000 pounds (907.185 kg). A metric ton (tonne) equals 1,000 kilograms (2,204.62 pounds). A metric ton is about 10% heavier than a short ton.
Complete list of Weight conversion units and its conversion.
- 1 kilogram [kg] = 1000 gram [g]
kg to g → - 1 kilogram [kg] = 2.2046226218 pound [lbs]
kg to lbs → - 1 kilogram [kg] = 35.2739619496 ounce [oz]
kg to oz →
- 1 kilogram [kg] = 0.1574730444 stone (UK)
kg to stone → - 1 gram [g] = 0.001 kilogram [kg]
g to kg → - 1 gram [g] = 1000 milligram [mg]
g to mg →
- 1 milligram [mg] = 0.001 gram [g]
mg to g → - 1 milligram [mg] = 0.000001 kilogram [kg]
mg to kg → - 1 milligram [mg] = 1000 microgram [µg]
mg to µg →
- 1 ton (metric) [t] = 1000000 gram [g]
metric ton to g → - 1 ton (metric) [t] = 1.1023113109 ton (short) (US)
metric ton to short ton → - 1 ton (metric) [t] = 0.9842065276 ton (long) (UK)
metric ton to long ton →
- 1 pound [lbs] = 453592.37 milligram [mg]
lbs to mg → - 1 pound [lbs] = 0.0714285714 stone (UK)
pounds to stone → - 1 pound [lbs] = 7000 grain [gr]
lbs to grain →
- 1 ounce [oz] = 0.0625 pound [lbs]
ounces to pounds → - 1 ounce [oz] = 28349.523125 milligram [mg]
oz to mg → - 1 ounce [oz] = 437.5 grain [gr]
oz to grain →
- 1 carat [car, ct] = 200 milligram [mg]
carat to mg → - 1 carat [car, ct] = 0.00705479239 ounce [oz]
carat to oz → - 1 ton (short) (US) = 907.18474 kilogram [kg]
short ton to kg →
- 1 ton (long) (UK) = 2240 pound [lbs]
long ton to lbs → - 1 ton (long) (UK) = 1.0160469088 ton (metric) [t]
long ton to metric ton → - 1 stone (UK) = 6.35029318 kilogram [kg]
stone to kg →
- 1 grain [gr] = 0.06479891 gram [g]
grain to g → - 1 grain [gr] = 64.79891 milligram [mg]
grain to mg → - 1 slug = 14.593902937 kilogram [kg]
slug to kg →
- 1 hundredweight (UK) = 50.80234544 kilogram [kg]
cwt (UK) to kg → - 1 hundredweight (UK) = 112 pound [lbs]
cwt (UK) to lbs → - 1 pennyweight [pwt] = 0.00155517384 kilogram [kg]
pwt to kg →
- 1 microgram [µg] = 0.000001 milligram [mg]
µg to mg → - 1 microgram [µg] = 1e-9 kilogram [kg]
µg to kg → - 1 nanogram [ng] = 0.001 microgram [µg]
ng to µg →
- 1 quarter (UK) [qr] = 12.70058636 kilogram [kg]
quarter (UK) to kg → - 1 quarter (UK) [qr] = 28 pound [lbs]
quarter (UK) to lbs → - 1 pound (troy) [lb t] = 0.3732417216 kilogram [kg]
troy pound to kg →
- 1 hectogram [hg] = 100 gram [g]
hg to g → - 1 dekagram [dag] = 10 gram [g]
dag to g → - 1 dekagram [dag] = 0.01 kilogram [kg]
dag to kg →
- 1 Atomic mass unit [Da] = 1.66053e-24 gram [g]
amu to g → - 1 gram [g] = 0.000001 ton (metric) [t]
g to ton → - 1 ton (metric) [t] = 1000000 gram [g]
ton to g →
- 1 kilogram [kg] = 1000000 milligram [mg]
kg to mg → - 1 kilogram [kg] = 0.001 ton (metric) [t]
kg to metric ton → - 1 kilogram [kg] = 5000 carat [car, ct]
kg to carat →
- 1 gram [g] = 0.0352739619 ounce [oz]
grams to ounces → - 1 gram [g] = 5 carat [car, ct]
g to carat → - 1 gram [g] = 15.4323583529 grain [gr]
g to grain →
- 1 milligram [mg] = 0.0000022046 pound [lbs]
mg to lbs → - 1 milligram [mg] = 0.005 carat [car, ct]
mg to carat → - 1 ton (metric) [t] = 1000 kilogram [kg]
metric ton to kg →
- 1 pound [lbs] = 0.45359237 kilogram [kg]
lbs to kg → - 1 pound [lbs] = 453.59237 gram [g]
pounds to grams → - 1 pound [lbs] = 16 ounce [oz]
pounds to ounces →
- 1 pound [lbs] = 0.0005 ton (short) (US)
lbs to short ton → - 1 ounce [oz] = 28.349523125 gram [g]
ounces to grams → - 1 ounce [oz] = 0.028349523 kilogram [kg]
oz to kg →
- 1 ounce [oz] = 141.747615625 carat [car, ct]
oz to carat → - 1 carat [car, ct] = 0.0002 kilogram [kg]
carat to kg → - 1 carat [car, ct] = 0.2 gram [g]
carat to g →
- 1 ton (short) (US) = 2000 pound [lbs]
tons to pounds → - 1 ton (short) (US) = 0.90718474 ton (metric) [t]
short ton to metric ton → - 1 ton (long) (UK) = 1016.0469088 kilogram [kg]
long ton to kg →
- 1 stone (UK) = 14 pound [lbs]
stone to pounds → - 1 stone (UK) = 6350.29318 gram [g]
stone to g → - 1 grain [gr] = 0.00006479891 kilogram [kg]
grain to kg →
- 1 slug = 32.1740486 pound [lbs]
slug to lbs → - 1 hundredweight (US) = 45.359237 kilogram [kg]
cwt (US) to kg → - 1 hundredweight (US) = 100 pound [lbs]
cwt (US) to lbs →
- 1 pennyweight [pwt] = 1.55517384 gram [g]
pwt to g → - 1 scruple [s.ap] = 0.0012959782 kilogram [kg]
scruple to kg → - 1 scruple [s.ap] = 1.2959782 gram [g]
scruple to g →
- 1 nanogram [ng] = 1e-12 kilogram [kg]
ng to kg → - 1 quarter (US) [qr] = 11.33980925 kilogram [kg]
quarter (US) to kg → - 1 quarter (US) [qr] = 25 pound [lbs]
quarter (US) to lbs →
- 1 pound (troy) [lb t] = 373.2417216 gram [g]
troy pound to g → - 1 poundal [pdl] = 0.014098081 kilogram [kg]
poundal to kg → - 1 hectogram [hg] = 0.1 kilogram [kg]
hg to kg →
- 1 decigram [dg] = 0.1 gram [g]
dg to g → - 1 centigram [cg] = 0.01 gram [g]
cg to g → - 1 Atomic mass unit [Da] = 1.66053e-27 kilogram [kg]
amu to kg →
- 1 ton (metric) [t] = 1000 kilogram [kg]
tons to kg → - 1 ton (metric) [t] = 35273.9619 ounce [oz]
ton to ounces → - 1 ounce [oz] = 0.0000283495 ton (metric) [t]
ounces to ton →