🧴 OZ to ML Converter: Fluid Ounces to Milliliters

What is the OZ to ML Converter?

An oz to ml converter exists because the United States measures liquids in fluid ounces while almost everywhere else, and most lab and pharmacy equipment, uses milliliters. The two units describe the same idea, volume, but on completely different scales, so reading a US recipe or supplement bottle against a metric measuring jug means converting oz to ml constantly. The exact factor is 1 US fluid ounce = 29.5735295625 ml, a value that comes directly from the legal definition of the US gallon (231 cubic inches, 128 fluid ounces per gallon, 2.54 cm per inch), not a rounded approximation.

To convert oz to ml, multiply the ounce figure by 29.5735295625. That gives 8 fl oz x 29.5735295625 = 236.5882365 ml, shown rounded as 236.59 ml, which is why a standard US cup of water is quoted as roughly 237 ml on nutrition panels. Going the other way, from ml to oz, you divide by the same factor: 500 ml / 29.5735295625 = 16.91 fl oz. This converter runs both operations off one constant, so the ounces and milliliters fields always agree no matter which one you edit.

The oz to ml conversion shows up constantly in the kitchen, at the pharmacy, and behind the bar. Cooks scaling a US recipe for a metric kitchen need to turn cups and fluid ounces of milk or oil into ml. Parents measuring liquid medicine often have a dose written in fl oz on the box but a syringe marked only in ml. Bartenders and baristas converting an ounce-based pour into the milliliter markings on European jiggers and glassware run the same math dozens of times a shift. In every case the exact multiplier avoids the drift that comes from rounding too early.

A quick mental shortcut helps for casual use: 1 fl oz is close to 30 ml, so 8 oz is roughly 240 ml and 16 oz is roughly 480 ml. That estimate is fine for a splash of water but not for dosing medicine or converting a whole recipe, where the small 1.4 percent gap between 30 and 29.5735295625 compounds across larger amounts. For anything measured precisely, use the full factor and let this oz to ml converter round only the final displayed answer.

When to use it

• Converting a US recipe written in fluid ounces or cups into the milliliters shown on a metric measuring jug.
• Reading a supplement or medicine bottle labeled in fl oz when the dosing syringe or cup is graduated in ml only.
• Checking a drink or bottle size, such as an 8 oz glass or a 16 oz can, against its milliliter equivalent on packaging.
• Converting bar pours and coffee recipes from US ounce measures into the ml markings on European barware.

How to use the OZ to ML Converter

1. Type the number of US fluid ounces into the Fluid ounces box; it is pre-filled with 8 as a starting example.
2. Read the milliliters result in the Milliliters box and the highlighted headline above the table.
3. To convert the other direction, type a milliliter figure into the Milliliters box and watch the ounces update.
4. Use Copy result to copy the headline, or Reset to return to the 8 fl oz example.

Formula & method

Worked examples

Common mL bottle and container sizes converted to fl oz

US fluid ounces to milliliters chart (exact factor 29.5735295625)

Common mistakes to avoid

• Mixing up US and UK fluid ounces. A US fluid ounce is 29.5735295625 mL, but a UK (imperial) fluid ounce is only 28.4130625 mL, about 4 percent smaller. Recipes, medicine doses and drink sizes from Britain, Ireland, Australia or Canada may use the imperial ounce, so confirm the source before converting oz to ml.
• Rounding the factor too early. Using 30 mL per ounce is a fine quick estimate but drifts as the amount grows: 16 oz at 30 becomes 480 mL instead of the correct 473.18 mL, a 6.8 mL gap. Multiply by the full 29.5735295625 and round only the final answer.
• Confusing fluid ounces with weight ounces. A fluid ounce measures volume, while a plain ounce (oz) on a kitchen scale measures weight. The two only line up for water. For flour, sugar or oil, 1 fl oz of volume does not weigh 1 oz, so this converter should not stand in for a weight conversion.
• Dividing instead of multiplying, or the reverse. To go from ounces to milliliters you multiply by 29.5735295625; to go from milliliters to ounces you divide by it. Flipping the operation gives an obviously wrong tiny or huge number, for example 8 / 29.57 = 0.27 instead of 236.59.

Glossary

US fluid ounce (fl oz)

A US customary unit of liquid volume equal to exactly 29.5735295625 mL, or one eighth of a US cup. There are 128 fluid ounces in a US gallon.

Milliliter (mL)

The metric unit of volume equal to one cubic centimeter. There are 1000 milliliters in one liter, and it is the standard liquid measure across most of the world.

UK (imperial) fluid ounce

The British fluid ounce, equal to 28.4130625 mL, slightly smaller than the US fluid ounce. Used in the UK and some Commonwealth countries.

Cup (US)

A US customary volume of 8 US fluid ounces, equal to 236.59 mL. This is the default 8 fl oz example this converter opens with.

Liter (L)

A metric volume of 1000 mL, equal to roughly 33.81 US fluid ounces. Larger drink bottles and jugs are usually labeled in liters.

Conversion factor

The fixed multiplier linking two units. For fluid ounces and milliliters it is 29.5735295625 mL per US fluid ounce, an exact value derived from the definition of the US gallon.

Frequently asked questions