US Teaspoons to Metric Teaspoons (tsp to tsp)
1 US teaspoon equals 0.9857843188 metric teaspoons (rounded).
How to convert US teaspoons to metric teaspoons
To convert US teaspoons to metric teaspoons, multiply the number of US teaspoons by 0.9857843188. The factor is rounded to 10 significant digits. To go the other way, multiply metric teaspoons by 1.014420681 (rounded).
metric teaspoons = US teaspoons × 0.9857843188
Example: 10 US teaspoons = 9.857843188 metric teaspoons.
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)
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
Metric Teaspoon (tsp)
Exactly 5 mL, used in most countries.
Five milliliters is the metric teaspoon, a figure so tidy that it has become the working definition for medicine and food labels. The traditional British teaspoon was an imperial fluid drachm, one eighth of an imperial fluid ounce, about 3.55 milliliters, and the American one was 4.93 mL. US nutrition labeling law now defines a teaspoon as exactly 5 milliliters.
The 5 mL teaspoon matters most when dosing medicine. Kitchen spoons vary widely, with one Greek survey of 71 household teaspoons finding volumes from 2.5 to 7.3 mL, so measuring spoons, syringes and calibrated cups are the safer tools. It also anchors the metric cooking system: three teaspoons make a 15 mL tablespoon, and fifty fit in a 250 mL metric cup. Australia keeps a 5 mL teaspoon but counts four of them in its larger 20 mL tablespoon.
1 metric teaspoon = 0.005 liters (exactly).
Sources: Wikipedia: Teaspoon; 21 CFR 101.9: nutrition labeling household measures; Wikipedia: Metric cup
Related conversions
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- US teaspoons to US cups
- US teaspoons to US fluid ounces
- US teaspoons to cubic meters
- US teaspoons to cubic centimeters
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- US teaspoons to US pints
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- US teaspoons to metric cups
- US teaspoons to metric tablespoons
- Liters to metric teaspoons
- Milliliters to metric teaspoons
- US gallons to metric teaspoons
- US cups to metric teaspoons
- US fluid ounces to metric teaspoons
- Cubic meters to metric teaspoons
- Cubic centimeters to metric teaspoons
- US quarts to metric teaspoons
- US pints to metric teaspoons
- US tablespoons to metric teaspoons
- Metric cups to metric teaspoons
- Metric tablespoons to metric teaspoons
See all volume units.