Teaspoons to mL Converter — tsp to mL

The Conversion: 1 Teaspoon = 4.92892 mL

One US teaspoon equals 4.92892 milliliters. This is the standard teaspoon used in American cooking and medicine dosing. For practical purposes, this is almost universally rounded to 5 mL.

• Teaspoons → mL: Multiply by 4.92892 (e.g., 3 tsp × 4.92892 = 14.79 mL)
• mL → Teaspoons: Divide by 4.92892 (e.g., 15 mL ÷ 4.92892 = 3.04 tsp)

Quick mental estimate: 1 teaspoon ≈ 5 mL. This approximation is so close (only 1.4% off) that it's used universally in medicine, nutrition labels, and most cooking. Three teaspoons = 1 tablespoon ≈ 15 mL.

Note on different teaspoons: The metric teaspoon is exactly 5 mL (used in Australia, UK modern recipes). The imperial teaspoon is 5.919 mL (historical UK). The US teaspoon at 4.929 mL is between the metric and older UK definitions. In practice, most of the world now uses the 5 mL metric teaspoon as the standard.

Teaspoons to Milliliters Conversion Table

Common teaspoon amounts converted to milliliters, with practical context:

Medicine Dosing: Why Teaspoons and mL Both Matter

The teaspoon-to-milliliter conversion is critically important in medicine, particularly for liquid medications, children's dosing, and over-the-counter remedies.

The 5 mL standard: The medical and pharmaceutical industries universally equate 1 teaspoon with 5 mL. Medicine cups, dosing syringes, and dropper instructions all use this equivalence. While the true US teaspoon is 4.93 mL, the 5 mL standard has been adopted because it's safer — a slight overdose of most medications is less dangerous than the confusion caused by fractional milliliters.

Why syringes beat spoons: The American Academy of Pediatrics recommends using a calibrated dosing syringe (marked in mL) rather than kitchen teaspoons for children's medication. Studies show that kitchen teaspoons vary in volume from 2.5 mL to 7.8 mL — a 3x range that can cause dangerous under- or over-dosing. A 2016 study in the Journal of Pediatrics found that parents using teaspoons were 2x more likely to give incorrect doses compared to those using mL-marked syringes.

• Infant acetaminophen: Typically dosed at 0.5–1.5 mL (0.1–0.3 tsp) depending on weight — impossible to measure accurately with a teaspoon
• Children's cough syrup: Usually 5 mL (1 tsp) for ages 6–11, 10 mL (2 tsp) for 12+
• Adult liquid medication: Often 10–30 mL (2–6 tsp) per dose
• Nutritional supplements: Fish oil, MCT oil, and liquid vitamins often specify both tsp and mL on labels

The FDA now recommends that all liquid medication labels use milliliters exclusively to reduce dosing errors. Many US pharmacies have stopped providing dosing cups marked in teaspoons and instead provide mL-only syringes. This shift is an ongoing process — many older adults and parents still think in teaspoons, making the conversion knowledge essential during the transition period.

US vs Metric vs Imperial Teaspoons

The teaspoon is not a single universal unit — there are several definitions still in use around the world:

The practical differences between US and metric teaspoons are tiny — just 1.4%. For virtually all cooking applications, they're interchangeable. The imperial teaspoon is about 20% larger than the US teaspoon, which can matter in recipes using several teaspoons of a strong ingredient like baking soda or chili powder.

Australia officially adopted the metric teaspoon (5 mL) in 1970 and has used it consistently since. The UK officially uses metric measurements but older recipes and many home cooks still use the imperial teaspoon. The US FDA defines the teaspoon as exactly 5 mL for nutrition and medicine labeling, even though the volumetric US teaspoon is 4.929 mL — another source of minor confusion that rarely matters in practice.

When following a recipe from any English-speaking country, using 5 mL for 1 teaspoon will always be close enough. The only time the US vs. metric distinction matters is in very precise laboratory or pharmaceutical work, where the volumetric teaspoon should be avoided entirely in favor of direct mL measurement.

Baking and Cooking: Teaspoon Precision

In baking, teaspoons are used for leavening agents, salt, extracts, and spices — ingredients where small differences in quantity produce large differences in results. Understanding the mL equivalence helps when scaling recipes or substituting measuring tools.

• Baking soda: ¼ teaspoon (1.23 mL) per cup of flour is a standard ratio. Too much creates a metallic, soapy taste; too little and nothing rises.
• Baking powder: 1–1¼ teaspoons (5–6 mL) per cup of flour for quick breads. Double-acting powder is more forgiving of measurement errors.
• Salt: 1 teaspoon (5 mL) of table salt weighs about 6 g, while 1 teaspoon of kosher salt weighs about 3–4 g depending on brand. The mL measurement is the same, but the weight (and saltiness) differs dramatically because of crystal size.
• Vanilla extract: 1–2 teaspoons (5–10 mL) per batch is standard. Pure vanilla is expensive ($4–6 per oz / $0.14–0.20 per mL), so accurate measurement prevents waste.
• Yeast: 1 standard packet = 2¼ teaspoons = 7 g = ~11 mL. Active dry and instant yeast are measured the same way in teaspoons but behave differently.

For scaling recipes: if a recipe for 12 muffins calls for 1 teaspoon of baking powder and you want to make 36, you need 3 teaspoons = 1 tablespoon = ~15 mL. Knowing that 1 tsp ≈ 5 mL makes mental arithmetic simple: 5 mL × 3 = 15 mL. This is easier than working with fractional teaspoons when scaling by odd factors like 1.5x or 2.5x.

Professional bakeries work entirely in grams and milliliters, reserving teaspoons only as an approximate reference for home cooks. When developing recipes for publication, baking professionals often provide both units: "1 teaspoon (5 mL) vanilla extract" or "½ teaspoon (2.5 mL) fine sea salt." This dual notation helps bridge the gap between home kitchen teaspoon drawers and the precision-focused metric world of professional pastry.

Nutritional Supplements and Liquid Vitamins

Many nutritional supplements — fish oil, MCT oil, liquid vitamin D, elderberry syrup, collagen peptides — are dosed in teaspoons while their nutritional data is reported per mL. Converting between the two is essential for accurate supplement tracking.

For athletes tracking macros precisely, every milliliter of oil-based supplements adds calories. One teaspoon (5 mL) of fish oil or MCT oil adds approximately 40–45 calories and 4.5–5 g of fat. Over a week of daily supplementation, that's 280–315 extra calories — enough to matter for competitors in weight-class sports or during a cutting phase.

When traveling internationally, knowing the tsp-to-mL conversion helps with purchasing supplements abroad. A European pharmacy selling liquid vitamin D at "10 mL" is selling about 2 teaspoons worth — helpful context when the label is in another language and the only familiar reference point is your kitchen teaspoon.

History of the Teaspoon as a Measurement

The teaspoon as a unit of measurement evolved from the actual spoon used for stirring tea. Tea became wildly popular in England in the 17th century, and the small spoon used to stir it became a practical kitchen reference for small quantities. By the 18th century, cookbooks were routinely using "teaspoonful" as a measurement, though the size was not standardized.

The standardization of the teaspoon happened differently in different countries. In the United States, the Fannie Farmer Cookbook (1896) was one of the first to insist on standardized, level measurements — before that, recipes used heaping or rounded teaspoons that varied wildly. The US standard was eventually set at 1/3 tablespoon = 1/48 cup = 4.92892 mL.

The international adoption of the 5 mL metric teaspoon came in the mid-20th century as countries metricated their measurement systems. Australia was one of the first English-speaking countries to fully adopt metric cooking measurements in 1970, followed by the UK and others. The 5 mL standard was chosen because it was close enough to existing teaspoons that recipes wouldn't need significant adjustment.

Today, the teaspoon remains one of the most commonly used measurements in home cooking worldwide. Despite the push toward metric measurements, millions of recipes — from grandmother's handwritten index cards to best-selling cookbooks — are written in teaspoons. The 5 mL equivalence makes the transition to metric relatively painless: 1 tsp ≈ 5 mL, 1 tbsp ≈ 15 mL, 1 cup ≈ 250 mL (Australian metric cup) or 237 mL (US cup).

Essential Oils and Aromatherapy Conversions

The teaspoon-to-mL conversion is frequently used in aromatherapy and DIY beauty products, where essential oils are measured in drops and mL while carrier oils are often measured in teaspoons and tablespoons.

Dilution ratios: Essential oils must be diluted in carrier oils before skin application. Standard dilution ratios are based on drops per teaspoon of carrier oil:

• 1% dilution (sensitive skin, children): 1 drop per teaspoon (5 mL) of carrier oil
• 2% dilution (general adult use): 2 drops per teaspoon (5 mL) of carrier oil
• 3% dilution (acute conditions): 3 drops per teaspoon (5 mL) of carrier oil
• 5% dilution (short-term use): 5 drops per teaspoon (5 mL) of carrier oil

One drop of essential oil ≈ 0.05 mL = 0.01 tsp. A standard 15 mL essential oil bottle contains about 300 drops, or roughly 3 teaspoons. Essential oil bottles come in 5 mL (1 tsp), 10 mL (2 tsp), 15 mL (3 tsp), and 30 mL (6 tsp) sizes. Knowing these mL-to-teaspoon equivalences helps estimate how many applications a bottle will provide.

For DIY beauty products — sugar scrubs, bath bombs, massage oils, lip balms — recipes are typically written in teaspoons for accessibility. Converting to mL allows for more precise measurement using a syringe or graduated dropper, which is especially important when working with potent essential oils where a fraction of a mL can mean the difference between a pleasant scent and skin irritation.