Weight Converter
1 kilogram equals 2.204623 pounds, and 1 ounce equals 28.349523 grams. This weight converter helps you switch a mass value from one unit to another without doing the base math by hand. Enter a number, choose the unit you have, choose the unit you want, and the tool converts between milligrams, grams, kilograms, pounds, and ounces. It is useful for cooking, shipping, fitness logging, classroom work, product labels, and quick metric-to-imperial checks when the original number is in the wrong unit for the task in front of you. The converter uses fixed standard unit factors and returns a rounded display value, so you can move from a tiny mg measurement to a large kg or lb value with the same method. If you only need to know how many pounds are in 5 kilograms, how many grams are in 16 ounces, or how many ounces are in a package marked in grams, this tool gives the answer fast and keeps the conversion path visible.
Quick answer
The converter supports mg, g, kg, lb, and oz, which covers most everyday weight and mass conversions people search for.
What this tells you
- •The converter supports mg, g, kg, lb, and oz, which covers most everyday weight and mass conversions people search for.
- •Each calculation runs through kilograms as the shared base unit, so the same logic works for gram-to-ounce, pound-to-milligram, and kilogram-to-pound conversions.
- •Results are rounded to 6 decimal places for display, which keeps the output readable while preserving useful precision for most planning and comparison tasks.
- •This tool converts mass units only. It does not estimate serving size, postage class, body composition, or product density.
How to Use
- 1Enter the number you want to convert in the Value field. Whole numbers and decimals both work, so inputs like 5, 2.75, or 0.125 are all valid.
- 2Pick the unit you have from the From menu: milligram (mg), gram (g), kilogram (kg), pound (lb), or ounce (oz).
- 3Pick the unit you want from the To menu, which offers the same five units.
- 4Click Convert to see the converted weight with the from and to units listed under it, so you can confirm the direction before you copy the number.
- 5If you are using the answer for packaging, nutrition labels, shipping paperwork, or technical documentation, keep the converted value for a quick check and confirm the final published figure against the standard required for that document.
How It Works
Formula
Converted weight = input × (source-to-kg factor) ÷ (target-to-kg factor)The tool first converts your starting value into kilograms because the formula code stores kilograms as the shared base unit for weight. It then divides that kilogram value by the factor for the target unit. For example, 16 oz becomes 16 × 0.028349523125 = 0.45359237 kg. Dividing by 0.001 converts that result to 453.59237 g after rounding to 6 decimal places. The same process works for every supported pair, which keeps the method consistent whether you are converting mg to g or lb to kg.
Calculation note: values are processed in the order shown above, using the current input units.
Worked Examples
Convert 5 kilograms to pounds
The formula multiplies 5 by the kilogram factor of 1 and then divides by the pound factor of 0.45359237. That gives 11.023113 pounds after rounding to 6 decimal places. This is a common conversion for body weight, luggage checks, and package specs when one system uses metric and the other uses imperial units.
Convert 16 ounces to grams
Sixteen ounces first convert to kilograms by multiplying 16 × 0.028349523125, which gives exactly 0.45359237 kg. Dividing by the gram factor of 0.001 gives 453.59237 g. This is useful when a recipe, food label, or shipping note lists ounces but your scale reads in grams.
Convert 150 pounds to kilograms
The converter multiplies 150 by 0.45359237 to move from pounds into kilograms. That produces 68.0388555 kg, which displays as 68.038855 kg after rounding. It is a practical check when gym equipment, travel forms, or health records need metric weight instead of pounds.
Convert 2500 milligrams to grams
Milligrams are one-thousandth of a gram, so the tool converts 2500 mg into kilograms and then back out to grams. The result is exactly 2.5 g. This kind of small-unit conversion helps when a parts list, powder measurement, or label switches between mg and g.
Convert 3 ounces to milligrams
Three ounces convert to kilograms as 3 × 0.028349523125 = 0.085048569375 kg. Dividing by the milligram factor of 0.000001 gives 85048.569375 mg. This example shows how quickly a small imperial unit can become a much larger metric count when you convert to milligrams.
Convert 11 st 4 lb to kilograms
Siobhan's UK clinic letter gives her weight as 11 st 4 lb, and her running club's sign-up form asks for kilograms. The converter has no stone unit, so she changes it to pounds first: 11 × 14 = 154, plus 4 makes 158 lb. Converting 158 lb to kg returns 71.667594 kg, which she enters as 71.7 kg. Reading 11 st 4 lb as 11.4 stone would have meant 159.6 lb and 72.39 kg, almost three quarters of a kilogram too heavy, because 4 lb is 4/14 of a stone, not 0.4.
Defined mass factors and what the converter shows
The pound has been exactly 0.45359237 kg since 1959, and the ounce, stone, and tons are fixed multiples of it. Factors marked exact are definitions. The others never terminate and are shown at the converter's six-decimal rounding. Units without their own menu entry were entered in pounds, kilograms, or grams as shown in the first column.
| Conversion | Factor | Exact or rounded | Converter output |
|---|---|---|---|
| 1 lb to kg | 0.45359237 | Exact | 0.453592 |
| 1 lb to g | 453.59237 | Exact | 453.59237 |
| 1 lb to oz | 16 | Exact | 16 |
| 1 oz to g | 28.349523125 | Exact | 28.349523 |
| 1 kg to lb | 1 / 0.45359237 | Rounded | 2.204623 |
| 1 kg to oz | 16 / 0.45359237 | Rounded | 35.273962 |
| 1 stone (14 lb) to kg | 6.35029318 | Exact | 6.350293 |
| 1 short ton (2,000 lb) to kg | 907.18474 | Exact | 907.18474 |
| 1 long ton (2,240 lb) to kg | 1,016.0469088 | Exact | 1016.046909 |
| 1 metric ton (1,000 kg) to lb | 1,000 / 0.45359237 | Rounded | 2204.622622 |
| 1 troy ounce (31.1034768 g) to oz | 480 / 437.5 grains | Rounded | 1.097143 |
| 1 troy pound (373.2417216 g) to lb | 5,760 / 7,000 grains | Rounded | 0.822857 |
Exact factors follow from the international pound of 0.45359237 kg, which NIST SP 811 Appendix B lists as an exact factor, and from the unit tables in NIST Handbook 44 Appendix C: 16 oz and 7,000 grains to the pound, 480 grains to the troy ounce, 12 troy ounces to the troy pound, 2,000 lb to the short ton, and 2,240 lb to the long ton. The stone of 14 lb is defined in Schedule 1 of the UK Weights and Measures Act 1985. Converter outputs are the tool's own results at six decimals.
Where the pound, ounce, stone, and ton come from
Since July 1, 1959, the avoirdupois pound has been defined as exactly 0.45359237 kg, under an agreement among six English-speaking countries that the US published in the Federal Register (24 FR 5348). NIST SP 811, the Guide for the Use of the International System of Units, lists that factor as exact in Appendix B, and NIST Handbook 44 Appendix C puts 16 ounces and 7,000 grains in the pound. The rest is arithmetic. An ounce is 28.349523125 g and a grain is 64.79891 mg, both exact. Going the other way never comes out even, which is why 1 kg shows as 2.204623 lb.
Rounding shows up in one place only. The display stops at six decimals, so 1 lb to kg reads 0.453592 even though the defined value runs to eight, and 1 kg to lb reads 2.204623 because the exact reciprocal never ends. Every stored factor is exact. The ounce is held as one sixteenth of the 0.45359237 kg pound, so 100 lb converts to exactly 1600 oz and 3 oz to 85048.569375 mg. For lab sheets and labels, convert once from the original value and round at the end, not at each step.
The oz in this tool is the avoirdupois ounce used for food, mail, and body weight. Precious metals are weighed in troy ounces, a separate system that shares only the grain. Handbook 44 sets the troy ounce at 480 grains, or 31.1034768 g, against 437.5 grains for the avoirdupois ounce, so a troy ounce is about 9.7 percent heavier. The troy pound runs the other way. Its 12 troy ounces make 5,760 grains, lighter than the 7,000-grain avoirdupois pound. To convert a troy weight here, enter it in grams. A 1 troy ounce coin reads 1.097143 oz on a kitchen scale.
A ton depends on who wrote it. Handbook 44 defines the short ton as 2,000 lb, or 907.18474 kg, and the long ton as 2,240 lb, or 1,016.0469088 kg. It also notes that ton with no qualifier is commonly understood as the 2,000-pound ton, and that the long ton sees only limited commercial use in the US, mostly in specialized industries. The metric ton, the US name for the tonne in NIST SP 811, is exactly 1,000 kg, or 2,204.622622 lb. The long ton is 12 percent heavier than the short ton, so check which one a freight quote or scrap ticket means. The converter has no ton unit, so enter 2,000 lb, 2,240 lb, or 1,000 kg.
The stone is 14 lb, which makes it exactly 6.35029318 kg. Schedule 1 of the UK Weights and Measures Act 1985 defines it, and you will mostly meet it in British body weights. With no stone unit in the menu, multiply the stones by 14, add the leftover pounds, and convert the total as lb. Do not read 11 st 4 lb as 11.4 stone. Four pounds is 4/14 of a stone, so 11 st 4 lb is about 11.29 st, and the decimal shortcut adds 1.6 lb, or about 0.73 kg.
Common mistakes
- Typing the wrong abbreviation. mg, g, kg, lb, and oz are very different in size, so a one-letter mistake can change the answer by a large amount.
- Mixing ounces and pounds mentally. There are 16 ounces in a pound, so using ounces where pounds were intended will throw off the result fast.
- Rounding too early during a longer workflow. Keep the full converted value until the last step if you still need to total, compare, or price several items.
- Using the converted weight as a final regulated label without checking the required rounding rule. Different documents and industries may require a specific number of decimals or a specific display unit.
- Expecting a weight conversion to solve a volume problem. Weight and volume are not interchangeable unless you also know the material density.
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