US Teaspoons to Milliliters (tsp to mL)

1 US teaspoon equals 4.928921594 milliliters (rounded).

1 US teaspoon = 4.928921594 milliliters

How to convert US teaspoons to milliliters

To convert US teaspoons to milliliters, multiply the number of US teaspoons by 4.928921594. The factor is rounded to 10 significant digits. To go the other way, multiply milliliters by 0.2028841362 (rounded).

milliliters = US teaspoons × 4.928921594

Example: 10 US teaspoons = 49.28921594 milliliters.

Pints, quarts, gallons and fluid ounces differ between the US and the UK. Units are labeled 'US' or 'imperial' to avoid confusion.

About these units

US Teaspoon (tsp)

US customaryCurrent unit

One sixth of a US fluid ounce, exactly 4.92892159375 mL. Commonly rounded to 5 mL in recipes.

Teaspoons arrived with tea. Small spoons were common in Europe from at least the 13th century, and the earliest cited mention of a teaspoon is a London Gazette advertisement from 27 December 1686. Britain's Commutation Act of 1784 cut the tea tax from 119 percent to 12.5 percent, tea became cheap, and cups and spoons grew with it. By the 1850s the culinary teaspoon had settled as one third of a tablespoon.

The US teaspoon is one sixth of a US fluid ounce, exactly 4.92892159375 milliliters, though for nutrition labels and medicine it is rounded to 5 mL. Apothecaries once called the small spoon cochleare minus, to distinguish it from the larger cochleare majus. Household spoons are poor measuring tools: one study of 71 kitchen teaspoons found volumes from 2.5 to 7.3 milliliters, which is why dosing instructions point to standard measuring spoons or syringes.

1 US teaspoon = 0.004928921594 liters (approximately).

Sources: Wikipedia: Teaspoon; NIST SP 811, Appendix B.8: conversion factors for volume; 21 CFR 101.9: nutrition labeling household measures

Milliliter (mL)

Metric (SI)Current unit

One thousandth of a liter, or exactly 1 cubic centimeter. Used for medicine, cooking and small containers.

Milliliters inherit everything from the liter, since the prefix simply means one thousandth. Because the liter is a cubic decimeter, a milliliter works out to exactly one cubic centimeter, a coincidence the metric system built in on purpose so that volume, length and mass interlock. One milliliter of water has a mass of about one gram, so a dosing syringe, a kitchen scale and a measuring jug can all be checked against one another.

Today milliliters dominate wherever small amounts must be measured precisely: medicine, flavorings, perfume, shampoo and the fine print on drink labels. Spelling is a mild regional split, with uppercase mL preferred in the United States, Canada and Australia and lowercase ml common in the UK and Europe. For scale, a US teaspoon is just under 5 mL, a US tablespoon is about 14.8 mL, and the US nutrition-label cup is exactly 240 mL, so one such cup is 240 of these tiny units.

1 milliliter = 0.001 liters (exactly).

Sources: Wikipedia: Litre; NIST SP 811, Appendix B.8: conversion factors for volume; 21 CFR 101.9: nutrition labeling household measures

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