There are 3 teaspoons in 1 tablespoon. This holds in both the US customary and metric systems, and it is exact, not rounded. From it, everything else follows: half a tablespoon is 1 1/2 teaspoons, 2 tablespoons is 6 teaspoons, and a full cup, at 16 tablespoons, works out to 48 teaspoons. It is the smallest link in the measuring chain and the one you will reach for most.
Teaspoon and tablespoon conversion table
Here are the small-volume conversions cooks use daily:
| Tablespoons | Teaspoons | Milliliters (approx.) |
|---|---|---|
| 1/2 tbsp | 1 1/2 tsp | 7.5 ml |
| 1 tbsp | 3 tsp | 15 ml |
| 2 tbsp | 6 tsp | 30 ml |
| 3 tbsp | 9 tsp | 45 ml |
| 4 tbsp (1/4 cup) | 12 tsp | 59 ml |
| 16 tbsp (1 cup) | 48 tsp | 237 ml |
The metric sizes
In milliliters, a US teaspoon is about 4.93 ml and a US tablespoon is about 14.79 ml, per NIST conversion data. The metric system rounds these to a clean 5 ml and 15 ml, and because the difference is tiny, the two are treated as interchangeable in the kitchen. That is why measuring spoons sold worldwide are typically marked 5 ml for a teaspoon and 15 ml for a tablespoon. The 3-to-1 ratio survives the rounding, since 15 divided by 5 is exactly 3.
Why this conversion matters most
Teaspoons and tablespoons carry the ingredients where a small error does the most damage: baking soda, baking powder, salt, yeast, and spices. Use a tablespoon of baking soda where the recipe wanted a teaspoon and you have tripled a powerful leavener, which can leave a soapy, metallic taste and a collapsed bake. Because the difference between the two spoons is exactly 3x, mixing them up is not a rounding error, it is a major one. That is the practical reason to keep the ratio locked in memory.
When you are missing a spoon
No tablespoon in the drawer? Measure 3 level teaspoons instead. No teaspoon, only a tablespoon? Fill the tablespoon and use a third of it, or better, use the fact that 1 tablespoon is 3 teaspoons to portion by eye for forgiving recipes. Going the other way scales cleanly too: a recipe calling for 5 teaspoons is 1 tablespoon plus 2 teaspoons. For the next step up, our guide to how many tablespoons are in a cup shows how these spoons build into cups.
Level, do not heap
A conversion only works if you measure correctly. “One teaspoon” in a recipe means a level teaspoon: fill it, then sweep the top flat with the straight edge of a knife. A heaped or rounded teaspoon of a dense powder can hold nearly twice the intended amount, which quietly throws off seasoning and leavening. This matters far more for dry ingredients than liquids, since a liquid naturally levels itself at the rim.
Scaling seasonings up and down
The 3-to-1 ratio shines when you resize a recipe. Doubling a dish that calls for 2 teaspoons of a spice? That is 4 teaspoons, or 1 tablespoon plus 1 teaspoon, which is faster to scoop as one tablespoon and one teaspoon than as four separate teaspoons. Halving a recipe with 1 tablespoon of soy sauce? Half of 3 teaspoons is 1 1/2 teaspoons. Working in teaspoons keeps the fractions clean and stops you from over- or under-seasoning when you change the yield.
Salt is the exception to watch
One place to slow down is salt, because not all salts fill a spoon the same way. A teaspoon of fine table salt packs far more actual salt than a teaspoon of flaky kosher salt, since the coarse flakes leave more air. The 3-teaspoons-per-tablespoon rule still holds as a volume conversion, but if a recipe specifies a salt type, use that type rather than assuming all teaspoons of salt season equally. For anything where precision really matters, weighing salt in grams removes the ambiguity entirely.
The same caution applies to any coarse or clumping ingredient, such as brown sugar, ground coffee, or grated cheese. Brown sugar is usually packed into the spoon, while granulated sugar is leveled loose, so the instruction in the recipe matters as much as the number. When a spice cakes together, break it up before you level it, or a single teaspoon can hide a hidden extra half. The conversion ratio never changes, but how much actually sits in the spoon does, so read the recipe’s wording as carefully as its numbers.
Drawer spoons are not measuring spoons
The spoons you eat with are not calibrated. A “teaspoon” from your cutlery set can range from about 3 to 7 ml depending on the pattern, and soup spoons are bigger still. For baking, leavening agents, and especially medicine dosing, always use marked measuring spoons rather than tableware. If you cook by weight, you can also cross-check using our guide to how many grams are in an ounce, though small spoon volumes are usually easier to measure than to weigh.
The bottom line
Three teaspoons make a tablespoon, everywhere, in both the US and metric systems. It is the most-used small conversion in cooking and the easiest to get wrong under pressure, so commit the 3-to-1 rule to memory and always measure level.
