What this mass converter does
This tool converts between the six mass units that appear in Pakistani school problems, everyday contexts and imported packaging: kilograms, grams, milligrams, pounds, ounces and the metric tonne. Enter a value, pick the from and to units, and the result appears instantly as you type. Every conversion is exact where the underlying factors are exact — the pound, ounce and metric tonne all have exact metric definitions agreed internationally. The page also includes a full reference table, a side-by-side diagram comparing mass and weight, and clear warnings about the three different "ton" variants (metric tonne, US short ton, UK long ton) so you never confuse one for another.
Mass ≠ weight — the crucial distinction
In everyday language, "weight" and "mass" are used interchangeably. In physics, they are two different quantities measured in different units.
The same mass, different weights
- 70 kg on Earth → weight = 70 × 9.8 = 686 N.
- 70 kg on the Moon → weight = 70 × 1.6 = 112 N (about 1/6 of Earth).
- 70 kg in free space → weight = 0 N (no gravity acting).
In all three cases the mass is still 70 kg. The mass has not changed — only the gravitational pull acting on it has. This is why a kilogram is defined by a physical standard (now an atomic constant) rather than by a gravitational force.
Because of this distinction, a "weight converter" on a physics page is really a mass converter. The correct name is mass converter. Instruments like a beam balance measure mass (by comparison against a standard) regardless of gravity; instruments like a spring scale measure weight (which changes with g). The digital body scale in your bathroom actually measures weight but displays mass in kg, because it assumes Earth's gravity.
Exact conversion factors
All imperial mass units have been defined exactly in terms of the kilogram since the 1959 international yard and pound agreement.
- 1 kg = 1000 g (exact)
- 1 g = 1000 mg (exact)
- 1 pound = 0.45359237 kg (exact)
- 1 ounce = 1/16 pound = 0.028349523125 kg (exact)
- 1 metric tonne = 1000 kg (exact)
A useful mental anchor: 1 kg ≈ 2.20462 lb. So a 70 kg adult is about 154 lb, and 1 lb is just under half a kilogram.
Worked examples
Example 1: 75 kg to pounds (body weight)
- 1 kg = 2.20462 lb.
- Result = 75 × 2.20462.
- Result = 165.35 lb.
- A 75 kg adult weighs about 165 pounds on a gym scale in the US or UK.
Example 2: 200 g to ounces (packaging)
- 1 g = 0.035274 oz.
- Result = 200 × 0.035274.
- Result = 7.0548 oz.
- A 200 g chocolate bar is about 7 ounces — an imported label would show this.
Example 3: 5 lb to kilograms (imported package)
- 1 lb = 0.45359237 kg.
- Result = 5 × 0.45359237.
- Result = 2.26796 kg.
- A 5 lb bag of flour is about 2.27 kg — a common conversion on foreign recipes.
Example 4: 1000 mg to grams (medicine dosage)
- 1 mg = 0.001 g.
- Result = 1000 × 0.001.
- Result = 1 g.
- A 1000 mg tablet contains 1 gram of active ingredient — a common paracetamol strength.
Example 5: 2 tonnes to kilograms (shipping)
- 1 t = 1000 kg.
- Result = 2 × 1000.
- Result = 2000 kg.
- Two metric tonnes is the shipping weight of a small truckload of material.
Example 6: 500 g to pounds (cooking)
- 1 g = 0.00220462 lb.
- Result = 500 × 0.00220462.
- Result = 1.10231 lb.
- Half a kilogram of sugar is just over a pound — the standard Western sugar bag size.
Example 7: 1 oz to grams (precious metals)
- 1 oz = 28.349523125 g.
- Result = 28.3495 g.
- Note: this is the avoirdupois ounce, used for general goods. Gold and silver use the troy ounce (31.1035 g), which is different.
Example 8: 100 lb to kilograms
- 1 lb = 0.45359237 kg.
- Result = 100 × 0.45359237.
- Result = 45.359237 kg.
- A 100 lb barbell weighs about 45.36 kg — the standard "45 kg" weight in gyms.
Full reference table
Exact equivalences for every unit pair. Use this table for quick mental estimates or to verify a computed value.
| Unit | In kilograms | In grams | In pounds |
|---|---|---|---|
| 1 mg | 1e-6 | 0.001 | 2.2046e-6 |
| 1 g | 0.001 | 1 | 0.00220462 |
| 1 kg | 1 | 1000 | 2.20462 |
| 1 t (tonne) | 1000 | 1,000,000 | 2204.62 |
| 1 oz | 0.0283495 | 28.3495 | 0.0625 |
| 1 lb | 0.453592 | 453.592 | 1 |
The exact pound-to-gram value is 453.59237 g. The table above shows it rounded to six significant figures. For most school and everyday conversions, 453.6 g is accurate enough; for laboratory work, use the exact factor.
The three "ton" variants — do not mix them up
The word "ton" is one of the most ambiguous units in everyday use. There are three different ones, and the difference is significant.
| Name | In kilograms | In pounds | Where used |
|---|---|---|---|
| Metric tonne (t) | 1000 | 2204.62 | Pakistan, most of the world, scientific contexts |
| US short ton | 907.185 | 2000 | US freight, US steel industry |
| UK long ton | 1016.05 | 2240 | UK historical, some UK shipping |
In Pakistani contexts, "tonne" (spelled with "-ne") always means the metric tonne = 1000 kg. When you see "ton" without a qualifier in a foreign document, check the country: US means short ton, UK means long ton (historically). For BISE science problems, always assume the metric tonne unless stated otherwise.
Common mistakes to avoid
- Using "kg" for weight in newtons. Weight is measured in newtons, not kilograms. A person's weight is 686 N, not 70 kg — 70 kg is their mass. Textbooks sometimes say "weighs 70 kg" as shorthand, but the physics quantity is mass.
- Confusing the metric tonne with the US or UK ton. 1 metric tonne = 1000 kg. 1 US short ton = 907.185 kg. 1 UK long ton = 1016.05 kg. The difference between metric tonne and short ton is about 10%, large enough to cause serious errors in shipping or engineering problems.
- Mixing avoirdupois ounces with troy ounces. The ounce on grocery packaging (avoirdupois) is 28.3495 g. The ounce for gold and silver (troy) is 31.1035 g. When a jeweller says "one ounce of gold", it is the troy ounce, which is about 10% heavier than the general ounce.
- Assuming "1 pound = 500 g" for rough work. A pound is 453.592 g, about 9% less than 500 g. For rough kitchen estimates 500 g is fine, but for any precise conversion use 453.592.
- Forgetting that mass is conserved in chemical and physical changes. Melting, freezing, dissolving, burning (in a closed system) — none of these change the total mass. Only nuclear reactions convert mass into energy (E = mc²), which is beyond BISE class 9 and 10 physics.
- Using "mass converter" and "weight converter" interchangeably without context. Instrument catalogs and scientific documents use "mass converter". Consumer packaging uses "weight converter" as a convenience term. It means the same thing in practice — but the physics distinction matters in exams.
- Rounding the pound value to 2.2 kg for scientific work. 1 kg = 2.20462 lb, not 2.2 lb. The 0.2% error is negligible for most everyday uses but unacceptable in lab work.
FAQ
What is the difference between mass and weight?
Mass is the amount of matter in a body, measured in kilograms (kg). It is the same everywhere — on Earth, the Moon, or in space. Weight is the gravitational force acting on that mass, measured in newtons (N), and it changes with location. Weight = mass × g, where g is the gravitational acceleration (about 9.8 m/s² on Earth, 1.6 m/s² on the Moon).
How do I convert kilograms to pounds?
Multiply kilograms by 2.20462. For example, 75 kg = 165.35 pounds. One pound is defined exactly as 0.45359237 kg since the 1959 international yard and pound agreement. To go the other way, multiply pounds by 0.45359237 to get kilograms.
What is the difference between a metric tonne, a short ton and a long ton?
A metric tonne (t) equals exactly 1000 kg. A US short ton equals 2000 pounds, about 907.185 kg. A UK long ton equals 2240 pounds, about 1016.05 kg. In Pakistan and most of the world, 'tonne' means the metric tonne. US freight and steel industries use short tons; UK historical contexts use long tons.
Why does this converter not include newtons?
Newtons measure force, not mass. Weight in newtons is a different physical quantity — it depends on gravity and varies by location. The converter handles mass units only. To convert mass to weight in newtons, multiply by g (about 9.8 m/s²), or use the force calculator's weight tool.
How many grams are in a pound?
Exactly 453.59237 grams. This follows from the exact definition 1 lb = 0.45359237 kg. Another useful anchor: 1 kg ≈ 2.20462 lb, and 1 lb ≈ 453.6 g. A standard 1 lb bag of coffee is about 454 g.
How do I read a Pakistani body-weight scale that shows both kg and lb?
The two dials or displays show the same mass in different units. 70 kg shows as about 154 lb. If you want the value in the other unit, either read the second dial or use this converter. Medical charts in Pakistan typically use kg, while some imported gym equipment uses lb.
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