About

Mis-measuring 1 cup of baking powder instead of 1 tsp introduces a 48× dosage error. In baking, where leavening ratios are calibrated to fractions of a gram, that mistake ruins the batch and wastes ingredients. This converter applies the exact US customary factor: 1 cup = 48 tsp, derived from 1 cup = 16 tbsp and 1 tbsp = 3 tsp. It handles fractional cups and arbitrary decimal inputs with selectable rounding precision.

Note: this tool uses US customary measurements. Australian cups (250 mL) and metric teaspoons (5 mL) yield a factor of 50, not 48. Japanese cups are 200 mL. Always verify which standard your recipe references before converting.

Formulas

The conversion between US cups and US teaspoons relies on two well-defined relationships in the US customary system:

1 cup = 16 tbsp = 16 × 3 tsp = 48 tsp

Cups to teaspoons:

V_tsp = V_cup × 48

Teaspoons to cups:

V_cup = V_tsp48

Where V_tsp is the volume in teaspoons and V_cup is the volume in cups. The factor 48 is exact within the US customary system. One US cup equals 236.588 mL and one US teaspoon equals 4.929 mL, yielding 236.588 ÷ 4.929 ≈ 48.000.

Reference Data

Cups (US)	Tablespoons (US)	Teaspoons (US)	Milliliters (mL)	Common Use
1/8	2	6	29.6	Small spice quantity
1/6	2.67	8	39.4	Some baking recipes
1/4	4	12	59.1	Standard small measure
1/3	5.33	16	78.9	Cake batter, sauces
3/8	6	18	88.7	Specialty recipes
1/2	8	24	118.3	Common baking measure
5/8	10	30	147.9	Specialty recipes
2/3	10.67	32	157.7	Flour, sugar measures
3/4	12	36	177.4	Standard large measure
7/8	14	42	207.0	Near-full cup
1	16	48	236.6	Standard US cup
1.25	20	60	295.7	Scaled recipes
1.5	24	72	354.9	1½ cup measure
1.75	28	84	414.0	Batch baking
2	32	96	473.2	1 US pint
2.5	40	120	591.5	Large batch
3	48	144	709.8	Triple recipe
4	64	192	946.4	1 US quart
8	128	384	1892.7	½ US gallon
16	256	768	3785.4	1 US gallon

Frequently Asked Questions

The factor of 48 is specific to US customary measurements: 1 US cup = 236.588 mL and 1 US tsp = 4.929 mL. In the metric/Australian system, 1 metric cup (250 mL) divided by 1 metric teaspoon (5 mL) gives exactly 50. Using the wrong factor introduces a 4.2% error, which compounds across multiple ingredients.

Multiply the fraction by 48. For 1/3 cup: 0.3333 × 48 = 16 tsp exactly. For 2/3 cup: 0.6667 × 48 = 32 tsp. Thirds divide evenly into 48 because 48 ÷ 3 = 16. This converter handles decimal and fractional inputs natively.

Yes. Cups and teaspoons are units of volume, not mass. 1 cup always equals 48 tsp regardless of the substance. However, measuring technique matters: flour scooped and leveled occupies a different mass than flour sifted and spooned into the same cup. The volume relationship remains 48∶1, but the weight of the measured ingredient varies.

1 US tablespoon = 3 tsp = 0.5 fl oz. Therefore 1 fl oz = 6 tsp, and 1 cup (8 fl oz) = 8 × 6 = 48 tsp. These relationships are defined by the US National Institute of Standards and Technology (NIST Handbook 44).

For leavening agents like baking soda (NaHCO₃), a 0.1 tsp rounding error on a 1 tsp dose is a 10% deviation. At 2 decimal places, precision is ±0.005 tsp (±0.025 mL), well within home kitchen tolerance. Professional pastry chefs working in grams should use 4+ decimal places when back-converting to volumetric measures.

Modern UK teaspoons are standardized at 5 mL (metric), while US teaspoons are 4.929 mL. The difference is 1.4% per teaspoon. Over 48 tsp (one cup), the cumulative difference is approximately 3.4 mL. Old Imperial teaspoons were approximately 3.55 mL, making them significantly smaller. Always confirm which system your recipe uses.