Unit Converter

Convert volume, weight, length, time and torque in seconds — millilitres to fluid ounces, grams to pounds, inches to centimetres, hours to days, newton-metres to foot-pounds and more. Pick a category, enter a value, choose the units, and the result updates as you type. It runs entirely in your browser: free, instant, no sign-in.

How the unit converter works

Every conversion goes through one standard factor. To convert, the tool multiplies your value by the size of the “from” unit in the category’s base unit, then divides by the size of the “to” unit. For example, 250 ml to fluid ounces is 250 ÷ 29.5735 = 8.453505 fl oz, because 1 US fluid ounce is 29.5735 ml. The result is rounded to 6 decimal places, which is more precision than any kitchen, workshop or homework question needs.

The factors are the standard ones: 1 US fluid ounce = 29.5735 ml, 1 US cup = 8 fl oz = 236.588 ml, 1 US quart = 4 cups = 946.353 ml; 1 ounce = 28.3495 g, 1 pound = 453.592 g, 1 kilogram = 2.20462 lb, 1 milligram = 1000 micrograms; 1 inch = 2.54 cm exactly, and 96 CSS pixels = 1 inch; 1 day = 24 hours; 1 newton-metre = 0.737562 foot-pounds. Pixels use the CSS reference pixel (96 px per inch), which is the standard for screens and web design — it is not a print resolution, so a printed image depends on its DPI setting.

Recipes, parcels, screen sizes, work schedules and torque wrenches all speak different units — and the same number can mean very different things depending on which one is meant. The Unit Converter switches between them instantly: millilitres to fluid ounces, grams to pounds, inches to centimetres, pixels to inches, hours to days and newton-metres to foot-pounds, across five categories — Volume, Weight, Length, Time and Torque. Pick a category, enter a value, choose the units, and the result updates as you type. It runs entirely in your browser, so nothing you enter is uploaded anywhere, and there is no sign-in and no limit on how often you use it.

Every conversion uses one standard factor, shown next to the result so you can check the maths yourself. The tool rounds results to 6 decimal places, which is more precision than any kitchen, workshop or homework question needs — and because the factors are exact standards, converting there and back returns the value you started with.

How to use the converter, step by step

There are four controls and one result box. Everything updates live — there is no button to press.

• Step 1 — Pick a category. Tap one of the five tabs at the top: Volume, Weight, Length, Time or Torque. The unit lists change to match the category.
• Step 2 — Enter the value. Type the number you want to convert, for example 250. Only zero or positive values are accepted — a negative volume, weight or length has no meaning here, and the tool will say so.
• Step 3 — Choose the units. Set the “From” unit (what you have) and the “To” unit (what you want). The Swap button exchanges the two, so you can convert straight back without retyping.
• Step 4 — Read the result. The big line shows the conversion, for example 250 ml = 8.453514 fl oz. Under it, the tool shows the factor it used — 1 fl oz = 29.5735 ml — so you can see exactly how the answer was reached.

Conversion factors used

These are the standard factors behind every conversion on this page. They are the same factors used in cookbooks, workshops, schools and engineering references.

• Volume: 1 US fluid ounce = 29.5735 ml; 1 US cup = 8 fl oz = 236.588 ml; 1 US quart = 4 cups = 32 fl oz = 946.353 ml.
• Weight: 1 ounce = 28.3495 g; 1 pound = 16 oz = 453.592 g; 1 kilogram = 1000 g = 2.20462 lb; 1 milligram = 1000 micrograms.
• Length: 1 inch = 2.54 cm exactly; 96 CSS pixels = 1 inch. Pixels use the CSS reference pixel, the standard for screens and web design.
• Time: 1 day = 24 hours.
• Torque: 1 newton-metre = 0.737562 foot-pounds.

All volume units here are US customary units — the fluid ounces, cups and quarts used in American recipes. A UK (imperial) fluid ounce is slightly smaller at 28.4131 ml, and a UK pint is 20 imperial fluid ounces rather than 16 US fluid ounces, so if a recipe is British, its “fl oz” is not the same as the one on this page. The weight units are avoirdupois ounces and pounds, the ones used for food, parcels and body weight — not troy ounces, which are used for precious metals and are heavier at 31.1035 g.

Worked examples

Example 1 — 250 ml to fluid ounces. 250 ÷ 29.5735 = 8.453514 fl oz. A 250 ml measuring jug holds about 8.45 US fluid ounces — just over one US cup.

Example 2 — 1 cup to millilitres. 1 cup = 8 fl oz, and 8 × 29.5735 = 236.588 ml. So 2 cups is 473.176 ml and half a cup is 118.294 ml.

Example 3 — 100 grams to ounces. 100 ÷ 28.3495 = 3.527399 oz. A 100 g chocolate bar weighs about 3.53 ounces.

Example 4 — 5 kilograms to pounds. 5 × 2.20462 = 11.0231 lb. A 5 kg bag of flour weighs just over 11 pounds.

Example 5 — 10 inches to centimetres. 10 × 2.54 = 25.4 cm. And the other way, 100 cm ÷ 2.54 = 39.370079 inches.

Example 6 — 192 pixels to inches. 192 ÷ 96 = 2 inches. At the standard 96 CSS pixels per inch, a 192-pixel-wide image is 2 inches wide on screen, and 192 px = 5.08 cm.

Example 7 — 48 hours to days. 48 ÷ 24 = 2 days. And 1000 hours is 1000 ÷ 24 = 41.666667 days.

Example 8 — 100 newton-metres to foot-pounds. 100 × 0.737562 = 73.7562 ft·lb. The other way, 50 ft·lb ÷ 0.737562 = 67.790911 N·m.

Common mistakes

• Mixing up fluid ounces and weight ounces. A fluid ounce measures volume and an ounce measures weight — they are different units that happen to share a name. 8 fl oz of water weighs about 8 oz, but 8 fl oz of honey weighs much more, because honey is denser than water. Convert volume to volume and weight to weight, and never swap the two.
• Using UK cups and quarts for a US recipe. A US cup is 236.588 ml and a US quart is 946.353 ml. The UK versions are different sizes, and an Australian cup is 250 ml. If a recipe gives strange results, check which country’s cup it means before blaming the converter.
• Treating pixels as a fixed physical size. Pixels only become inches through a resolution: 96 CSS pixels per inch is the web standard, but a phone screen packs far more pixels into an inch and a printed photo depends on its DPI setting. The px-to-inches result on this page is the CSS reference size, which is right for screens and web design, not a print measurement.
• Forgetting that a pound is 16 ounces, not 10. Weight in the imperial system is not decimal: 1 lb = 16 oz, so 8 oz is half a pound, not 0.8 of a pound. The converter handles this for you, but it is the most common mental-arithmetic slip.
• Rounding too early. Converting 100 g to ounces gives 3.527399 oz — rounding that to 3.5 oz and converting back gives 99.223 g, not 100 g. Keep the full result while you work, and round only at the end. The converter shows 6 decimal places for exactly this reason.

Related tools

The unit converter sits with ToolZana’s everyday maths tools, and three companion tools cover the rest of the numbers you meet most often.

• Percentage Calculator — work out any percentage, percentage increase or decrease, or what percentage one number is of another.
• Tip Calculator — work out the tip, the total bill and each person’s share when splitting a bill.
• Gold Weight Converter — convert gold weights between grams, tola, ounces and kilograms.

For all of ToolZana’s free tools, start at the ToolZana home page.

The short version

The Unit Converter converts volume, weight, length, time and torque using standard factors: 250 ml = 8.453514 fl oz, 1 cup = 8 fl oz = 236.588 ml, 1 quart = 4 cups = 946.353 ml, 100 g = 3.527399 oz, 1 lb = 453.592 g, 5 kg = 11.0231 lb, 10 in = 25.4 cm, 192 px = 2 in at 96 px per inch, 48 hours = 2 days, and 100 N·m = 73.7562 ft·lb. Pick a category, enter a value, choose the units, and the result updates as you type. The tool is free, runs entirely in your browser, and needs no sign-in.

Frequently Asked Questions

How many ounces are in a cup?

There are 8 US fluid ounces in 1 US cup. In millilitres, 1 US cup is 236.588 ml, because 8 × 29.5735 ml (one fluid ounce) = 236.588 ml. So 2 cups is 16 fl oz or 473.176 ml, and half a cup is 4 fl oz or 118.294 ml. This is the US customary cup used in American recipes; a UK cup and an Australian cup (250 ml) are different sizes, so check which country a recipe comes from before converting.

How do I convert ml to oz?

Divide the millilitres by 29.5735, because 1 US fluid ounce is 29.5735 ml. For example, 250 ml ÷ 29.5735 = 8.453514 fl oz, and 1000 ml ÷ 29.5735 = 33.814057 fl oz. To go the other way, multiply fluid ounces by 29.5735: 1 fl oz × 29.5735 = 29.5735 ml, and 8 fl oz × 29.5735 = 236.588 ml. Enter the value in the converter, pick Volume, and set the units to ml and fl oz — it does the division for you and shows the factor it used.

How many cups are in a quart?

There are 4 US cups in 1 US quart. A quart is also 32 US fluid ounces and 946.353 ml, because 4 cups × 236.588 ml = 946.352 ml, rounded to 946.353 ml from the exact quart factor. So 2 quarts is 8 cups, and half a quart is 2 cups. Like the cup, this is the US customary quart used in American recipes; the UK (imperial) quart is larger, at about 1136.5 ml, so make sure the recipe and the converter are using the same system.

How do I convert grams to ounces?

Divide the grams by 28.3495, because 1 ounce is 28.3495 grams. For example, 100 g ÷ 28.3495 = 3.527399 oz, and 500 g ÷ 28.3495 = 17.636995 oz. To go the other way, multiply ounces by 28.3495: 1 oz × 28.3495 = 28.3495 g, and 16 oz × 28.3495 = 453.592 g, which is exactly 1 pound. Enter the value in the converter, pick Weight, and set the units to grams and ounces — it does the division for you.

How many grams are in a pound?

There are 453.592 grams in 1 pound. A pound is also 16 ounces, and 16 × 28.3495 g (one ounce) = 453.592 g. So 2 lb is 907.184 g, half a pound is 226.796 g, and a quarter pound is 113.398 g. This is the avoirdupois pound used for food, parcels and body weight. Do not confuse it with the troy pound used for precious metals, which is lighter at 373.242 g and is not used in everyday weighing.

How do I convert inches to centimetres?

Multiply the inches by 2.54, because 1 inch is exactly 2.54 cm. For example, 10 in × 2.54 = 25.4 cm, and 1 in × 2.54 = 2.54 cm. To go the other way, divide centimetres by 2.54: 100 cm ÷ 2.54 = 39.370079 inches. The factor is exact by international definition, so inches and centimetres convert without any rounding error in the factor itself — only the displayed result is rounded, to 6 decimal places.

How do I convert pixels to inches?

Divide the pixels by 96, because the CSS standard is 96 pixels per inch. For example, 192 px ÷ 96 = 2 inches, and 96 px ÷ 96 = 1 inch. To go the other way, multiply inches by 96: 2.5 in × 96 = 240 px. This is the CSS reference pixel used for screens and web design, so a 192-pixel image is 2 inches wide on screen and 5.08 cm wide. It is not a print measurement — a printed image depends on its DPI setting, and a phone screen packs far more pixels into a physical inch.

How do I convert hours to days?

Divide the hours by 24, because 1 day is 24 hours. For example, 48 hours ÷ 24 = 2 days, 72 hours ÷ 24 = 3 days, and 1000 hours ÷ 24 = 41.666667 days. To go the other way, multiply days by 24: 1.5 days × 24 = 36 hours, and 12 hours is half a day. Pick the Time category in the converter, enter the hours, and set the units to hours and days — the result updates as you type.

How do I convert newton-metres to foot-pounds?

Multiply the newton-metres by 0.737562, because 1 N·m is 0.737562 ft·lb. For example, 100 N·m × 0.737562 = 73.7562 ft·lb, and 10 N·m × 0.737562 = 7.37562 ft·lb. To go the other way, divide foot-pounds by 0.737562: 50 ft·lb ÷ 0.737562 = 67.790911 N·m. Torque figures in car manuals and tool specifications are usually given in one of these two units, so this conversion is the one to use when a manual says 100 N·m and your torque wrench is marked in foot-pounds.

How many micrograms are in a milligram?

There are 1000 micrograms in 1 milligram. A microgram (mcg) is one millionth of a gram and a milligram (mg) is one thousandth of a gram, so the step between them is a factor of 1000. For example, 500 mg × 1000 = 500000 mcg, and the other way, 250 mcg ÷ 1000 = 0.25 mg. This conversion matters most for medicines and supplements, where doses are often listed in mcg on one label and mg on another — always double-check the unit before taking a dose, because 1000 mcg and 1000 mg differ by a factor of a thousand.

How do I convert kilograms to pounds?

Multiply the kilograms by 2.20462, because 1 kg is 2.20462 lb. For example, 5 kg × 2.20462 = 11.0231 lb, and 1 kg × 2.20462 = 2.20462 lb. To go the other way, divide pounds by 2.20462: 2.20462 lb ÷ 2.20462 = 1 kg. Kilograms are the metric unit for body weight and luggage in most of the world, while pounds are used in the US, so this is the conversion to use when a scale or an airline baggage limit is in the other unit. Enter the value in the converter, pick Weight, and set the units to kilograms and pounds.

Is the unit converter free?

Yes — the Unit Converter is completely free, with no sign-in and no limits. It runs entirely in your browser, so nothing you enter is uploaded anywhere, and you can use it as often as you like, for any of the five categories: Volume, Weight, Length, Time and Torque. There are no accounts, no downloads and no paid features — every conversion on the page works the same way, whether you convert once or a hundred times.