How many mL is 1 fluid ounce?

1 US fluid ounce = 29.574 mL (exact: 29.5735295625 mL). Note that 1 UK/Imperial fluid ounce = 28.413 mL — different from the US measure.

How many mL is 1 cup?

1 US cup = 236.588 mL. Other countries use different cup sizes: Australian cup = 250 mL; UK cup = 284 mL (½ UK pint). Use the US cup (236.588 mL) for clinical and nutritional calculations unless otherwise specified.

Volume Converter – mL to fl oz, Litres, Cups, Teaspoons

Q: How many mL is 1 teaspoon?

1 US teaspoon = 4.929 mL (exact: 4.92892159375 mL per NIST). In clinical practice, 5 mL is used as the standard teaspoon volume for oral liquid medications.

Volume Conversion Reference

Accurate volume conversion is critical in clinical settings — particularly for oral liquid medications where doses are expressed in mL but patients measure in teaspoons or tablespoons, and for IV therapy where infusion bags are labelled in mL but flow rates must be calculated in mL/hr. This converter uses NIST-exact conversion factors for all US customary units.

Key Volume Conversion Factors

Unit	mL Equivalent	Clinical Use
1 teaspoon (clinical)	5.000 mL	Standard for oral liquid prescribing; rounded from 4.929 mL for ease
1 US teaspoon (exact)	4.929 mL	NIST-exact value; used for precise calculations
1 tablespoon	14.787 mL	= 3 teaspoons; used in nutrition and compounding
1 US fluid ounce	29.574 mL	Oral syringes, liquid medications in US labelling
1 UK fluid ounce	28.413 mL	Different from US — check label origin carefully
1 US cup	236.588 mL	Nutritional labelling; hydration tracking
1 US pint	473.176 mL	Blood product volumes; fluid replacement reference
1 US gallon	3,785.41 mL	Large-volume references; dialysis fluid volumes

Clinical vs. Exact Teaspoon

In clinical practice, 1 teaspoon = 5 mL is the universally used approximation for prescribing and dispensing oral liquid medications. The exact US teaspoon (4.929 mL) differs by less than 1.5%, which is clinically insignificant for most medications. However, for high-potency drugs or when precise compounding is required, the exact value should be used. Our converter uses the exact NIST value (4.929 mL) for accuracy.

US vs. UK Volume Units

The US and UK both use fluid ounces and pints, but the values differ:

Unit	US	UK (Imperial)
Fluid ounce	29.574 mL	28.413 mL
Pint	473.18 mL (16 fl oz)	568.26 mL (20 fl oz)
Gallon	3,785.41 mL	4,546.09 mL

When interpreting international drug labels or patient reports, always verify which measurement system is being used.

Frequently Asked Questions

How many mL is 1 teaspoon of medicine?+

For clinical purposes, 1 teaspoon of medicine = 5 mL. This is the standard approximation used in prescribing, dispensing, and patient instructions worldwide. When a prescription says "take 1 teaspoon," it means 5 mL. A standard oral medicine spoon or syringe marked in mL is the most accurate way to measure. Kitchen teaspoons vary in size and should not be used for drug dosing.

What is the difference between US and UK fluid ounces?+

A US fluid ounce = 29.574 mL; a UK (Imperial) fluid ounce = 28.413 mL. The difference is approximately 4%. For clinical drug labelling, US fluid ounces are used on US products and UK fluid ounces on UK products. Always check the label origin when converting. This converter includes both — select "UK Fluid Ounce" or "US Fluid Ounce" in the unit selector.

How do I convert mL to cups for nutrition tracking?+

1 US cup = 236.588 mL. To convert mL to cups, divide by 236.588. For example, 500 mL ÷ 236.588 = 2.11 cups. For daily water intake tracking, 8 cups per day ≈ 1,893 mL ≈ 1.9 L. For a personalised daily water intake calculation based on your weight and activity level, see our Daily Water Intake Calculator.

Related Tools on MediCalc Pro

For IV fluid therapy rate calculations, see the IV Drip Rate Calculator which converts between mL/hr, drops/min, and infusion time. For daily fluid requirements based on body weight, see the Daily Water Intake Calculator and for paediatric fluid requirements (Holliday-Segar), see Pediatric Fluid Requirement. For drug concentration conversions (mg/mL to %), see the Drug Concentration Converter. For general unit conversion across weight, height, temperature, and more, see the Universal Unit Converter.

References

National Institute of Standards and Technology. Metric Conversions — Official SI Guide. NIST, 2023.
United States Pharmacopeia. USP 40 — Volume Measurement Standards. USP, 2023.

⚠️ Clinical Note: Always use calibrated oral syringes or measuring cups for liquid medication doses. Household spoons vary significantly in volume and are not appropriate for drug dosing. A 5 mL oral syringe is the recommended tool for paediatric liquid medications.