Convert Weight & Mass Units Instantly Convert between milligrams, grams, kilograms, ounces, pounds, metric tons, and stones in real time.

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Weight Converter

Convert between milligrams, grams, kilograms, ounces, pounds, metric tons, and stones in real time.

Enter the weight

Type a numeric value into the "From" field.

Choose your units

Select the source unit (e.g., kilograms) and the target unit (e.g., pounds).

View the converted weight

The converted weight appears immediately. Use the swap button to reverse direction.

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What Is Weight Converter?

A weight converter translates measurements between metric mass units (milligrams, grams, kilograms, metric tons) and imperial/customary units (ounces, pounds, stones). Technically, "weight" is a force (mass × gravity) while "mass" is an intrinsic property, but in everyday use the terms are interchangeable. The kilogram is the SI base unit of mass, currently defined by the Planck constant since the 2019 redefinition. The pound avoirdupois is defined as exactly 0.45359237 kg by international agreement. The stone (14 pounds) is still commonly used in the UK and Ireland for body weight. Our converter uses these exact definitions to provide precise, real-time conversions between all seven supported units, covering everything from pharmaceutical dosages in milligrams to shipping weights in metric tons.

Why Use Weight Converter?

Real-time conversion — results update as you type.
Covers both metric (mg, g, kg, t) and imperial (oz, lb, stone) units.
Bidirectional input: type in either field.
Uses internationally agreed exact conversion factors.
Reference table for quick lookups of common conversions.
No server calls — everything runs in your browser.

Common Use Cases

Cooking & Baking

Convert recipe ingredients between grams, ounces, and pounds.

Fitness & Health

Track body weight across different measurement systems (kg, lb, stone).

Shipping & Logistics

Translate package weights into the required units for international shipping labels.

Science & Pharmacy

Switch between milligrams, grams, and kilograms for dosages and lab measurements.

Technical Guide

One avoirdupois ounce is exactly 1/16 of a pound, or 28.349523125 grams. A stone equals 14 pounds, or precisely 6.35029318 kg.

The metric ton (tonne) equals exactly 1,000 kilograms, or approximately 2,204.62 pounds. It is distinct from the US short ton (2,000 pounds) and the British long ton (2,240 pounds); our converter uses the metric ton.

It works by converting the input to a base unit (kilograms) using exact multiplication factors, then converting from kilograms to the target unit by dividing by that unit's factor. This ensures that chaining conversions (e.g., oz → kg → lb) gives the same result as a direct conversion (oz → lb).

Important distinction: Troy ounces (used for precious metals) differ from avoirdupois ounces. One troy ounce = 31.1035 g, while one avoirdupois ounce = 28.3495 g. This tool uses avoirdupois ounces, which are standard for everyday use.

Tips & Best Practices

1
Quick estimate: 1 kg ≈ 2.2 lb. For more precision, multiply kg by 2.20462.
2
To convert stones to pounds, multiply by 14.
3
For cooking, remember: 1 oz ≈ 28 g is usually precise enough for recipes.
4
A metric ton is about 10% heavier than a US short ton.
5
When dealing with very small masses, milligrams give better precision than fractional grams.

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Frequently Asked Questions

Q How many pounds are in a kilogram?

One kilogram equals approximately 2.20462 pounds.

Q What is a stone in pounds?

One stone equals exactly 14 pounds, or about 6.35 kilograms.

Q Is mass the same as weight?

Technically no — mass is a measure of matter (in kg), while weight is a force (in newtons) dependent on gravity. However, in everyday contexts and on this converter, they are used interchangeably.

Q What is the difference between a metric ton and a US ton?

A metric ton (tonne) is 1,000 kg (≈2,204.6 lb). A US short ton is 2,000 lb (≈907.2 kg). A British long ton is 2,240 lb (≈1,016 kg).

Q How do I convert ounces to grams for cooking?

Multiply ounces by 28.35. For example, 4 oz ≈ 113.4 grams.

About This Tool

Weight Converter is a free online tool by FreeToolkit.ai. All processing happens directly in your browser — your data never leaves your device. No registration or installation required.