Weight and Mass Converter

What this weight and mass converter does

This weight and mass converter helps you quickly convert between common metric, imperial, US customary, cooking, body weight, shipping, and small mass units. You can use it as a kg to lbs converter, lbs to kg converter, grams to ounces converter, ounces to grams converter, stone to kg converter, tons to kilograms converter, or milligrams to grams converter in one place.

The converter uses kilograms as the base unit. That keeps the math consistent whether you are converting tiny units like micrograms and milligrams, everyday units like grams and pounds, body weight units like kilograms and stones, or heavy units like metric tons, US tons, and UK tons.

If you are working with other measurement types, you may also need the Measurement and Conversion Tools hub, the Length and Distance Converter, the Volume and Capacity Converter, the Temperature Converter, or the Area Converter.

Weight vs mass explained in simple terms

Mass and weight are closely related, but they are not exactly the same thing. Mass measures how much matter an object has. Weight measures the force of gravity acting on that mass. In physics, mass stays the same whether you are on Earth, the Moon, or in space, while weight can change depending on gravity.

In everyday life, people usually use the words weight and mass together. A person says they weigh 70 kilograms or 154 pounds, even though kilograms are technically a unit of mass and pounds are often used as a unit of weight in daily language. For practical conversions like cooking, fitness, shipping, school, shopping, and luggage, this converter treats these common units in the usual everyday way.

If your measurement task includes distance, speed, time, or travel planning, the Speed Converter, Time Duration Calculator, and Travel Time Calculator can help you complete the calculation.

How to convert weight units manually

The most reliable way to convert weight and mass units is to use one base unit. This converter uses kilograms. First, it multiplies your value by the kilogram factor of the starting unit. Then it divides that kilogram value by the kilogram factor of the target unit.

For example, one pound is exactly 0.45359237 kilograms. To convert 150 pounds to kilograms, multiply 150 by 0.45359237. The result is about 68.039 kilograms. To convert 70 kilograms to pounds, divide 70 by 0.45359237. The result is about 154.324 pounds.

This same method works for every unit in the converter. For grams, the kilogram factor is 0.001. For ounces, the kilogram factor is 0.028349523125. For stones, the kilogram factor is 6.35029318. For a metric ton, the kilogram factor is 1000. Using one base unit helps avoid errors when jumping between metric and imperial systems.

Metric weight and mass units explained

Metric mass units are based on powers of ten, which makes them easier to scale up or down. A kilogram is 1000 grams. A gram is 1000 milligrams. A milligram is 1000 micrograms. A metric ton, also called a tonne, is 1000 kilograms.

Metric units are common around the world in food packaging, medicine, science, school work, shipping labels, health tracking, and fitness. A recipe may list flour in grams. A supplement label may list an ingredient in milligrams. A package may list shipping weight in kilograms. A large shipment may use metric tons.

For household planning, you may also find the Household and Utility Tools, Household Expense Calculator, Electricity Bill Calculator, and Laundry Cost Calculator useful.

Imperial and US customary weight units explained

Imperial and US customary weight units include ounces, pounds, stones, US tons, and UK tons. These units are common in the United States, the United Kingdom, and some international shopping, fitness, shipping, cooking, and product listings.

One pound equals 16 ounces. One stone equals 14 pounds. One US ton, also called a short ton, equals 2000 pounds. One UK ton, also called a long ton, equals 2240 pounds. Because these units do not follow powers of ten, converting them mentally can be harder than converting metric units.

This is where a converter is useful. It prevents common mistakes like treating a US ton and UK ton as the same, or assuming ounces and fluid ounces are interchangeable. Ounces measure weight or mass, while fluid ounces measure volume. If you need liquid conversions, use the Volume and Capacity Converter or the Cooking Converter.

Kilograms to pounds and pounds to kilograms

Kilograms and pounds are two of the most searched weight conversions because they are used for body weight, gym equipment, luggage, product listings, and shipping. One pound is exactly 0.45359237 kilograms. One kilogram is about 2.20462 pounds.

To convert kilograms to pounds, divide the kilogram value by 0.45359237. To convert pounds to kilograms, multiply the pound value by 0.45359237. For a quick example, 70 kilograms is about 154.324 pounds, while 150 pounds is about 68.039 kilograms.

For body weight and fitness planning, you may also use the Calorie Burn and Steps Calculator, Step to Distance Calculator, and Height Converter.

Grams to ounces and ounces to grams

Grams and ounces are common in cooking, food labels, coffee, baking, small packages, jewelry, and product weights. One ounce equals exactly 28.349523125 grams. To convert ounces to grams, multiply by 28.349523125. To convert grams to ounces, divide by 28.349523125.

For example, 100 grams is about 3.527 ounces. Eight ounces is about 226.796 grams. This can be helpful when you follow recipes from another country, compare serving sizes, or check ingredient weights on international food packaging.

Keep in mind that weight ounces and fluid ounces are not the same. Ounces measure mass or weight. Fluid ounces measure volume. If a recipe says 8 oz flour, that may mean weight. If it says 8 fl oz milk, that means liquid volume. For recipe-specific conversions, the Cooking Converter is a better fit.

Stones, pounds, and kilograms for body weight

Stones are still commonly used for body weight in the UK and Ireland. One stone equals 14 pounds, which is 6.35029318 kilograms. If someone weighs 10 stone, that equals 140 pounds or about 63.503 kilograms.

When converting body weight, the exact number may include decimals. That is normal. You can round the final result depending on how precise you need to be. For casual tracking, one decimal place may be enough. For medical, athletic, or official records, use the precision required by the organization or professional guidance.

If you are converting body measurements too, the Length and Distance Converter and Height Converter may be useful companions.

Tons, metric tons, US tons, and UK tons explained

The word ton can be confusing because it does not always mean the same thing. A metric ton, also called a tonne, equals 1000 kilograms. A US ton, also called a short ton, equals 2000 pounds, or 907.18474 kilograms. A UK ton, also called a long ton, equals 2240 pounds, or 1016.0469088 kilograms.

This difference matters for shipping, freight, construction, agriculture, recycling, vehicle weight, industrial materials, and international trade. If a document only says ton, check whether it means metric ton, US ton, or UK ton before making a decision.

For trip, fuel, and transport planning, you may also want the Fuel Cost Calculator, Trip Budget Calculator, Packing List Generator, and Travel and Lifestyle Tools.

Small units like milligrams, micrograms, grains, and carats

Small mass units are important when precision matters. Milligrams are common on supplement, nutrition, and medicine labels. Micrograms are even smaller and are often used for tiny ingredient amounts. One milligram is 0.001 grams, while one microgram is 0.000001 grams.

Carats are commonly used for gemstones. One carat equals 200 milligrams, or 0.0002 kilograms. Grains are used in some specialized contexts, including certain historical, scientific, and technical measurements. One grain equals 0.00006479891 kilograms.

Because small units can create very tiny decimal results, the converter may use scientific notation when that is easier to read. This helps avoid long strings of zeros while still keeping the result accurate and practical.

Common weight and mass conversion table

Practical examples for cooking, fitness, shipping, school, and travel

For cooking, weight conversions help when recipes use grams but your kitchen scale shows ounces, or when a package lists ounces but a recipe needs grams. Baking especially benefits from weight-based measuring because grams are more precise than cups for flour, sugar, butter, and other ingredients.

For fitness and body weight, kilograms and pounds are often mixed across apps, gym equipment, health forms, and international programs. A workout plan may list dumbbells in pounds, while your local gym may label weights in kilograms. A body weight goal may be written in pounds, while your scale displays kilograms.

For shipping and online shopping, product weight affects delivery cost, luggage planning, package handling, and comparisons between sellers. A seller may list an item in pounds, while your courier or airline uses kilograms. If the item size also matters, use the Length and Distance Converter for dimensions and the Packing List Generator for travel organization.

For school and science, weight and mass conversions help students understand metric relationships, unit factors, and formula-based thinking. If your assignment also includes dates, time, or schedules, the Date Difference Calculator, Business Days Calculator, and Pomodoro Timer can help with planning and study sessions.

Mistakes to avoid when converting weight or mass

One common mistake is mixing up ounces and fluid ounces. Ounces measure weight or mass, while fluid ounces measure volume. This matters in cooking because 8 ounces of flour by weight is not the same as 8 fluid ounces of milk by volume.

Another mistake is assuming all tons are the same. A metric ton, US ton, and UK ton are different. That difference is large enough to matter for shipping, freight, construction, and heavy equipment.

A third mistake is rounding too early. If you are converting several values, keep more precision during the calculation and round the final answer only after the main conversion is finished. This helps avoid avoidable errors in recipes, school work, product weights, and shipping estimates.

Finally, check the unit label carefully. A value in mg is not the same as g. A value in lb is not the same as oz. A value in metric tons is not the same as US tons. Reading the label first is often the easiest way to prevent an incorrect conversion.