Scale Explorer

Microscopic

How big is a tardigrade?

Tardigrade · Phylum Tardigrada (all species) · Tardigrada

Body length (range across species)
50–2,100 µm 0.002–0.083 in range
Typical size
up to 1 mm 0.039 in maximum
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Human hair (width), Grain of sand, Tardigrade, Human drawn to the same scaleHuman hair (width): average diameter ≈ 70 µm (too small to see at this scale). Grain of sand: grain diameter (sand size class) 0.0625–2 mm (too small to see at this scale). Tardigrade: body length (range across species) 50–2,100 µm (too small to see at this scale). Human: height 1.61–1.75 m.Human hair (width): ≈ 70 µm (too small to see at this scale)Grain of sand: 0.0625–2 mm (too small to see at this scale)Tardigrade: 50–2,100 µm (too small to see at this scale)Human: 1.61–1.75 mHuman1.61–1.75 mHuman hair (width)≈ 70 µm · too small to seeGrain of sand0.0625–2 mm · too small to seeTardigrade50–2,100 µm · too small to see

Human hair (width), Grain of sand and Tardigrade are too small to see at this scale and are marked with ▲.

Everything is drawn to the same scale, standing on the same ground line. Silhouettes are simplified outlines scaled to the measured dimension. A faded outline shows the top of a size range.

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Dimensions

MeasurementMetricImperialNotesSource
Body length (range across species) 50–2,100 µm 0.002–0.083 in Range of body lengths across tardigrade species, from the smallest to the largest known. Range: varies [1]
Typical size up to 1 mm up to 0.039 in Britannica: most tardigrades are about 1 mm (0.04 inch) or less. Maximum [2]

About the tardigrade

Tardigrades, or water bears, are tiny eight-legged invertebrates that live in damp moss, sand, fresh water and the sea around the world. Adults of different species span roughly 50 to 2,100 micrometres in length, and most are about a millimetre or smaller. They are known for surviving drying out and other extreme conditions, which has made them a subject of space research.

  • About 1,200 tardigrade species are known according to this review, and the true number is thought to be much higher. [1]
  • The body has a head segment followed by four segments, each carrying one pair of unjointed legs that usually end in claws. [1]
  • Adult tardigrades live roughly two to several months. [1]
  • Tardigrades live in damp moss, on flowering plants, in sand, in fresh water and in the sea. [2]

How many fit?

  • ≈ 770–35,000 × Tardigrade · body length (range across species) lined up end to end match the Human · height
  • ≈ 1–30 × Human hair (width) · average diameter lined up end to end match the Tardigrade · body length (range across species)

Counts divide one sourced figure by another. "End to end" uses each object's main measurement; weight and volume rows appear only when both figures are sourced.

How it compares

  • 0.7–30× A tardigrade is roughly as long as the width of a human hair is wide: between 0.7 and 30 times, depending on size. See side by side
  • 0–34× A tardigrade is roughly as long as a grain of sand is wide: between 0 and 34 times, depending on size. See side by side
  • 1/1.6–100 A black garden ant is about 1.6–100 times as long as a tardigrade. See side by side
  • 1/3.1–150 A grain of rice is about 3.1–150 times as long as a tardigrade. See side by side
  • 1/4.8–300 A honeybee is about 4.8–300 times as long as a tardigrade. See side by side
  • 1/770–35,000 An average adult is about 770–35,000 times as tall as a tardigrade is long. See side by side

Factors compare the body length (range across species) of a tardigrade with each object’s own main measurement (height for a human). Where a size varies, the factor is given as a range.

Notes on these figures

  • Size varies widely by species; the 50 to 2,100 micrometre range covers the whole phylum, not a single species.
  • No source giving a tardigrade's mass was found, so mass is left out.

Sources

  1. Origins of Life and Evolution of the Biosphere (via PubMed Central), Tardigrades in Space Research - Past and Future (Erdmann W., Kaczmarek Ł.; vol. 47). Accessed 25 September 2026.
  2. Encyclopaedia Britannica, Tardigrade. Accessed 25 September 2026.

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