Convert US teaspoons to milliliters in seconds

Ever stared at a recipe calling for 3 teaspoons of vanilla extract, only to find your measuring spoons mysteriously missing? Or maybe you’ve needed to convert children’s medication from teaspoons to milliliters for accurate dosing? This tsp to mL conversion is one of those everyday math problems that seems simple—until you’re elbow-deep in cookie dough or worried about giving the right dose. Let’s break it down so you’ll never second-guess these measurements again.

Unit definitions

What is a US teaspoon (tsp)?

A US teaspoon is a volume unit primarily used in cooking and baking.

• Symbol: tsp
• Common uses: Measuring spices, extracts, and small liquid quantities
• Definition: 1 US teaspoon = 1/6 US fluid ounce = ¹⁄₃ US tablespoon

Fun fact: The teaspoon as we know it evolved from 17th-century European cutlery. Early recipes literally instructed cooks to use their personal tea spoons!

What is a milliliter (mL)?

A milliliter is a metric unit of volume equal to one-thousandth of a liter..

• Symbol: mL
• Common uses: Scientific measurements, medication dosages, international recipes
• Definition: 1 mL = 1 cm³ (exactly the volume of a cube measuring 1 cm × 1 cm × 1 cm)

Milliliters became widespread after the 1960s when most countries adopted the metric system. They’re preferred in medicine because syringes can measure mL precisely.

Conversion formula

The magic number here is 4.92892. To convert:

• tsp to mL: Multiply teaspoons by 4.92892
• mL to tsp: Divide milliliters by 4.92892

Let’s say your German cake recipe requires 15 mL of baking powder. How many US teaspoons is that?
15 mL ÷ 4.92892 ≈ 3.043 tsp → you’d use about 3 teaspoons

Example calculations

1. Converting 1.5 tsp to mL
   1.5 tsp × 4.92892 = 7.39338 mL → Rounded to 7.3934 mL
2. Converting 25 mL to tsp
   25 mL ÷ 4.92892 ≈ 5.0721 tsp → Approximately 5.0721 teaspoons

Conversion tables

US teaspoons to milliliters

Milliliters to US teaspoons

Historical background

The teaspoon’s journey began in 17th-century England as actual cutlery used for tea. By the 1800's, it became a standardized US measurement. Meanwhile, the milliliter emerged from the French metric system in 1795 , designed to create universal measurements. Today’s exact tsp-to-mL ratio resulted from 20th-century efforts to align customary units with metric precision.

Interesting facts?

1. Not all teaspoons are equal: A UK teaspoon holds 5.91939 mL—about 20% more than its US cousin
2. Medical precision: US pharmacies switched to mL for prescriptions in the 1970s to prevent dosing errors
3. Baking secret: Professional bakers prefer weighing ingredients (grams) over volume measurements for consistency
4. Space-age conversions: NASA uses milliliters exclusively in spacecraft to maintain metric standardization
5. Coffee connection: A standard coffee scoop (2 tablespoons) equals 29.5735 mL—almost exactly 6 US teaspoons

FAQ