Weight Converter

What is a weight converter?

A weight converter changes a mass from one unit into all the others at once — milligrams, grams, kilograms, metric tonnes, ounces, pounds and stones. Instead of memorizing dozens of separate conversion factors, you type one number, pick its unit, and every equivalent appears side by side. The tool is built for recipes, shipping labels, gym plates, lab work, postage, and any moment you have a figure in one system and need it in another.

It mixes both measurement worlds in a single panel: the metric units (mg, g, kg, t) used almost everywhere, and the imperial / avoirdupois units (oz, lb, st) still common in the United States and United Kingdom. Because all seven update together, you can read across systems without doing the math by hand.

How does the weight converter work?

It uses a base-unit method: your value is first converted to grams using the exact factor for your chosen unit, then that gram amount is divided by each target unit’s size in grams. Using a single base unit keeps every conversion consistent and avoids rounding drift from chaining factors together.

The formula is:

grams = value × (factor of your unit), then result = grams ÷ (factor of each target unit).

The exact factors the widget uses come from international (NIST-defined) standards:

Unit	Symbol	Grams per unit (exact)
Milligram	mg	0.001
Gram	g	1
Kilogram	kg	1,000
Metric tonne	t	1,000,000
Ounce	oz	28.349523125
Pound	lb	453.59237
Stone	st	6350.29318

Notice that the pound is defined as exactly 0.45359237 kg, the ounce is exactly one-sixteenth of a pound (453.59237 ÷ 16 = 28.349523125 g), and a stone is exactly 14 pounds (453.59237 × 14 = 6350.29318 g). Results are shown to 7 significant figures, so very large or very tiny numbers stay readable.

What are some worked examples?

Example 1 — 70 kilograms to pounds. First convert to grams: 70 × 1,000 = 70,000 g. Then divide by the pound factor: 70,000 ÷ 453.59237 = 154.3236 lb. The same body mass is also 70,000 g, 70 kg, and about 11.02 stone (70,000 ÷ 6350.29318 = 11.02311 st).

Example 2 — 16 ounces to grams. Convert to the base unit: 16 × 28.349523125 = 453.5924 g, which is exactly 1 pound (16 oz = 1 lb), or about 0.4535924 kg. This shows why a “pound” on a scale and “16 ounces” are the same mass.

Example 3 — 5 kilograms to pounds and ounces. 5 × 1,000 = 5,000 g. Pounds: 5,000 ÷ 453.59237 = 11.02311 lb. Ounces: 5,000 ÷ 28.349523125 = 176.3698 oz. A 5 kg dumbbell is therefore just over 11 lb.

What is the quick kg-to-lb reference table?

For the most common everyday conversion — kilograms to pounds — multiply by 2.20462. This table uses the exact factor and is handy for body weight, luggage, and gym plates.

Kilograms (kg)	Pounds (lb)
1	2.204623
5	11.02311
10	22.04623
20	44.09245
50	110.2311
70	154.3236
75	165.3467
90	198.416
100	220.4623

To reverse it (pounds to kilograms), divide by 2.20462 or multiply by 0.45359237.

When would you use a weight converter?

This tool fits a wide range of daily and professional tasks:

• Cooking and baking: turn a recipe’s grams or ounces into the unit on your scale.
• Shipping and postage: convert package mass between kilograms and pounds for couriers.
• Fitness: read gym plates and dumbbells labeled in kg as lb, or track body weight in stone. For training maths, pair it with the one-rep max calculator.
• Health and dosing: convert milligrams and grams for supplements or nutrition labels.
• Travel: check airline baggage limits stated in kg against scales reading in lb.
• Trade and freight: convert tonnes to kilograms for bulk materials.

You can find more unit tools, including the length converter and the speed converter, on the converters category page.

What is the difference between mass and weight?

In everyday language “weight” and “mass” are used interchangeably, and this converter handles mass units — the amount of matter in an object. Strictly speaking, mass stays the same everywhere, while true weight is a force equal to mass times gravitational acceleration, so it changes with location (you would weigh less on the Moon even though your mass is identical).

For practical purposes on Earth this distinction does not affect your conversions: a kilogram of flour is the same kilogram whether you call it mass or weight. Kitchen, bathroom, and shipping scales are all calibrated for normal Earth gravity, so the grams, pounds, and stones they show line up with this tool.

Tips and common mistakes

• Pick the right “from” unit. The most frequent error is leaving the unit on the wrong setting; the math is exact, so a wrong starting unit gives a wrong-but-confident answer.
• Do not confuse ounces with fluid ounces. This tool converts mass ounces (avoirdupois), not volume. A fluid ounce measures liquid volume and is a different quantity entirely.
• Watch the troy ounce. Precious metals use the troy ounce (about 31.1 g), which is heavier than the standard ounce (28.35 g) used here. This converter uses the standard avoirdupois ounce.
• Mind significant figures. Displayed results are rounded to 7 significant figures. For legal-for-trade or laboratory work, use a certified scale rather than a converted estimate.
• Stones combine with pounds in the UK. Body weight is often written as, say, 11 st 4 lb; convert the whole figure to pounds (11 × 14 + 4 = 158 lb) before entering it.

Are there any limitations?

The converter assumes standard, internationally defined units and rounds output to 7 significant figures, so it is ideal for everyday and most professional use but is not a substitute for a calibrated, certified scale where legal accuracy matters. It does not handle troy or apothecary weights, and it treats mass and weight as equivalent under Earth gravity.

Disclaimer: This tool is provided for general information and convenience. For commercial transactions, medical dosing, shipping compliance, or any situation with legal or safety consequences, verify the figure with an approved, calibrated measuring device or a qualified professional.