One US tablespoon equals 0.5 fluid ounces, or exactly half a fluid ounce. That means 2 tablespoons make 1 fluid ounce, and 1 tablespoon holds 15 milliliters of liquid. This is the standard used across American recipes, nutrition labels, and medicine dosing.
Quick Conversion Table
- 1 tablespoon = 0.5 fl oz (15 mL)
- 2 tablespoons = 1 fl oz (30 mL)
- 4 tablespoons = 2 fl oz (¼ cup)
- 8 tablespoons = 4 fl oz (½ cup)
- 16 tablespoons = 8 fl oz (1 cup)
Each tablespoon also contains 3 teaspoons, so if you’re working with smaller measurements, 6 teaspoons equal 1 fluid ounce.
Fluid Ounces vs. Weight Ounces
This is where people get tripped up. A fluid ounce (fl oz) measures volume, meaning how much space something takes up. A regular ounce (oz) measures weight, meaning how heavy something is. They share a name but they are not the same thing.
For water, the numbers happen to land close together: 1 fluid ounce of water weighs roughly 1 ounce. But this breaks down with other ingredients. A tablespoon of honey weighs more than a tablespoon of flour, even though both occupy the same 0.5 fluid ounces of space. One cup of raw spinach weighs about 1 ounce, while one cup of broccoli florets weighs about 3.25 ounces. Same volume, very different weights. When a recipe calls for ounces, check whether it means fluid ounces (volume) or weight ounces. If it says “fl oz,” reach for a measuring spoon or cup. If it says “oz” for a dry ingredient, a kitchen scale gives you the most accurate result.
The Australian Exception
If you’re following an Australian recipe, pay close attention. An Australian tablespoon is 20 mL, not 15 mL. That’s a full teaspoon more than the standard used in the US, UK, and New Zealand. An Australian tablespoon holds four teaspoons instead of three. This difference is large enough to throw off baked goods, sauces, and anything where proportions matter. Check whether the recipe defines a tablespoon as 15 mL or 20 mL before you start measuring.
The US and imperial (UK) fluid ounce also differ slightly. A US fluid ounce is 29.57 mL, while an imperial fluid ounce is 28.41 mL. For a single tablespoon this gap is negligible, but it adds up in larger volumes since imperial pints, quarts, and gallons are all bigger than their US equivalents.
What the FDA Uses
The FDA defines a tablespoon as exactly 15 mL for nutrition labeling purposes. This is the number printed on every Nutrition Facts panel in the United States. The same regulation sets a fluid ounce at 30 mL and a cup at 240 mL. So when a cereal box says a serving is “2 tablespoons,” that means 30 mL, or 1 fluid ounce, measured with a proper measuring spoon.
Why Silverware Spoons Give Wrong Measurements
A tablespoon from your silverware drawer is not a measuring tablespoon. This matters most for liquid medicine, where accuracy can affect how well a dose works or whether it causes side effects.
A study published in the Annals of Internal Medicine asked 195 participants to pour a specific dose of cold medicine into different household spoons. Even in a well-lit room with a practice pour, people consistently got the dose wrong. Using a larger spoon, they poured 11.6% too much. Using a smaller spoon, they poured 8.4% too little. Participants were confident they had measured correctly in both cases. Over several days of dosing every 4 to 8 hours, those small errors compound. Researchers flagged inaccurate spoon dosing as a significant cause of pediatric poisonings.
For cooking, a casual tablespoon from your drawer is fine for adding olive oil to a pan. For baking, medicine, or anything where precision counts, use a calibrated measuring spoon or an oral syringe.