Mass and Weight Converter

Convert kilograms, pounds, stones, ounces, and newtons, and see how mass differs from weight.

Last updated:
Round (decimal places):

Was this calculator helpful?

★ ★ ★ ★ ★
Embed this calculator

Calculation Examples

Calculation Case Result
150 Pounds to Kilograms 68.04 kg
5 Kilograms to Pounds 11.02 lbs
1 Stone to Kilograms (UK) 6.35 kg
10 Kilograms to Newtons (Earth) 98.07 N
Mihail Doncenco
Mihail Doncenco Site Creator & Calculator Expert

Founder and developer of CalcMate. Builds and maintains every calculator on this site, focusing on formula accuracy and clear, practical results.

Mass vs. Weight: What is the Difference?

In daily speech, mass and weight mean the same thing. In physics they do not. Mass is the amount of matter in an object, measured in kilograms, and it stays the same everywhere. Weight is the gravitational force on that mass, measured in newtons, and it changes with local gravity. Newton's second law links them: \[W = m \times g\] where \(W\) is weight in newtons, \(m\) is mass in kilograms, and \(g\) is the standard acceleration of gravity, fixed by convention at exactly \(9.80665\text{ m/s}^2\) (adopted by the CGPM in 1901). Example: 70 kg weighs \(70 \times 9.80665 = 686.5\text{ N}\) on Earth. A bathroom scale measures that force but displays it as kilograms.

How the Conversion Logic Works

Mass to weight uses \(W = m \times g\), and the reverse is \(m = W \div g\). Unit-to-unit conversions use fixed factors. The pound is exactly 0.45359237 kg (international yard and pound agreement, 1959), so 1 kg is 2.20462 lb, 1 lb is 16 oz or 453.592 g, 1 oz is 28.3495 g, and 1 stone is 14 lb or 6.35029 kg. A metric tonne is 1,000 kg, and a centner (metric quintal) is 100 kg. Since the 2019 SI redefinition, the kilogram itself is defined through the Planck constant. BIPM maintains the SI definitions, and NIST Special Publication 811 (2008 edition) lists the customary factors.Kilograms to pounds conversion reference chart

Useful Tips 💡

  • One stone is exactly 14 lb. A person weighing 11 stone 4 lb weighs 158 lb, or about 71.7 kg.
  • In physics and engineering, keep mass (kg) and weight (N) apart. Mixing them up changes a result by a factor of about 9.8.
  • One kilogram-force is exactly 9.80665 N. A load rated at 500 kgf is therefore 4,903.3 N.

📋Steps to Calculate

  1. Enter the numeric value you wish to convert.

  2. Select the source unit (for example, Kilograms) and the target unit (for example, Stones or Newtons).

  3. Click "Calculate" to receive the converted mass value and, where applicable, the equivalent gravitational force in Newtons.

Mistakes to Avoid ⚠️

  1. Confusing net weight with gross weight in shipping. Net is the goods alone, and gross includes packaging, pallets, and containers.
  2. Using 2.2 lb per kg for precise work. The exact factor is 2.20462, so 100 kg is 220.46 lb and not 220 lb. On a 20-tonne freight load the shortcut is off by about 92 lb.
  3. Treating ounces (mass) as fluid ounces (volume). A US fluid ounce of water weighs about 29.6 g, or 1.04 oz, but a US fluid ounce of honey weighs about 42 g.
  4. Assuming a centner is always 100 kg. The metric quintal is 100 kg, but the old German Zentner is 50 kg and the US hundredweight is 100 lb (45.36 kg).

Practical Applications📊

  1. Body weight: 11 stone 4 lb is 158 lb or 71.7 kg, and 150 lb is 68.04 kg.

  2. Shipping: a 24 kg parcel is 52.9 lb, and a 1,000 kg pallet is 1 tonne or 2,204.6 lb.

  3. Physics: a 10 kg crate weighs 98.07 N on Earth and 16.2 N on the Moon, although its mass stays 10 kg.

  4. Cooking: 8 oz of butter is 226.8 g, and 1 lb of flour is 453.6 g.

Questions and Answers

Can the converter be used for cooking and baking?

Yes, and weights beat cups for baking. Ratios of flour, water, and leavening decide the crumb, and a measuring cup of flour changes with how it is scooped and packed. Use grams for accuracy: 1 oz is 28.35 g, 8 oz is 226.8 g, and 1 lb is 453.6 g. The converter handles grams, ounces, pounds, and kilograms, so you can scale a US recipe in ounces to a European one in grams.

How accurate is the mass and weight converter for professional use?

The factors are exact or carry more digits than any display needs. One pound is exactly 0.45359237 kg (1959), which gives 1 kg = 2.2046226 lb to eight digits. Standard gravity is exactly \(9.80665\text{ m/s}^2\) by convention, and 1 stone is exactly 14 lb. Results are computed without intermediate rounding. For commercial trade involving large quantities, still verify against a certified scale traceable to national metrology standards.

How do you convert mass to weight in Newtons?

Multiply the mass in kilograms by the local gravitational acceleration. On Earth, \(g = 9.80665\text{ m/s}^2\), so 10 kg gives \(10 \times 9.80665 = 98.07\text{ N}\). On the Moon, where \(g \approx 1.62\text{ m/s}^2\), the same mass weighs 16.2 N. On Mars, where \(g \approx 3.71\text{ m/s}^2\), it weighs 37.1 N. The mass stays 10 kg in all three places. Aerospace engineers design equipment around this difference.

What is a mass and weight converter and how does it work?

A mass and weight converter changes measurements between units of mass (grams, kilograms, ounces, pounds, stones, tonnes) and units of force (newtons). Mass-to-mass conversions use fixed factors, such as 1 kg = 2.20462 lb. Mass-to-weight conversions use \(W = m \times g\) with \(g = 9.80665\text{ m/s}^2\). Example: 5 kg is 11.02 lb and, on Earth, 49.03 N. People use it for body weight, cooking, freight, and physics problems.

What is the difference between mass and weight?

Mass is the amount of matter in an object and does not change with location, while weight is the gravitational force on that mass and does. Mass is measured in kilograms and is a scalar. Weight is a force, so it is measured in newtons and is a vector. A 70 kg person has a mass of 70 kg everywhere, but weighs about 686 N on Earth, 113 N on the Moon, and 260 N on Mars. In shopping and health contexts, "weight" usually means mass in kg or lb, but in physics and engineering the two must be kept separate.

Which formulas does the mass and weight converter use?

It uses three kinds of formula. Weight from mass: \(W = m \times g\) with \(g = 9.80665\). Mass from weight: \(m = W \div g\). Unit-to-unit mass conversions use fixed ratios: \(1\text{ kg} = 2.20462\text{ lb}\), \(1\text{ lb} = 453.592\text{ g}\), \(1\text{ stone} = 6.35029\text{ kg}\), and \(1\text{ tonne} = 1{,}000\text{ kg}\). Example: a 49.03 N weight on Earth is \(49.03 \div 9.80665 = 5\text{ kg}\).

Why do some countries use stones for body weight?

The stone is a traditional British unit equal to exactly 14 pounds, about 6.35 kg. It is still common for body weight in the United Kingdom and Ireland, in health articles, fitness tracking, and clinic conversations, although most trade and science there use metric units. Example: 11 stone 4 lb is 158 lb or 71.7 kg. The converter includes stones for people who track weight this way.
Disclaimer: This calculator is designed to provide helpful estimates for informational purposes. While we strive for accuracy, financial (or medical) results can vary based on local laws and individual circumstances. We recommend consulting with a professional advisor for critical decisions.