Scale Explorer

Microscopic

How big is a grain of ragweed pollen?

Pollen grain · Common ragweed (Ambrosia artemisiifolia) pollen · Ambrosia artemisiifolia

Diameter (hydrated grain)
16–20 µm 16–20 µm range
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Red blood cell, Pollen grain, Human hair (width), Human drawn to the same scaleRed blood cell: diameter 7.5–8.7 µm (too small to see at this scale). Pollen grain: diameter (hydrated grain) 16–20 µm (too small to see at this scale). Human hair (width): average diameter ≈ 70 µm (too small to see at this scale). Human: height 1.61–1.75 m.Red blood cell: 7.5–8.7 µm (too small to see at this scale)Pollen grain: 16–20 µm (too small to see at this scale)Human hair (width): ≈ 70 µm (too small to see at this scale)Human: 1.61–1.75 mHuman1.61–1.75 mRed blood cell7.5–8.7 µm · too small to seePollen grain16–20 µm · too small to seeHuman hair (width)≈ 70 µm · too small to see

Red blood cell, Pollen grain and Human hair (width) 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
Diameter (hydrated grain) 16–20 µm 16–20 µm Size of hydrated pollen under light microscopy; shortest and longest diameters both 16-20 µm. Range: varies [1]

About the grain of ragweed pollen

Pollen grains carry the male reproductive cells of seed plants, and their size and surface pattern differ from species to species. A grain of common ragweed pollen is a small spiny sphere with three openings. The PalDat pollen database measures hydrated ragweed grains at 16 to 20 micrometres across.

  • Ragweed pollen is spheroidal with a spiny (echinate) surface and three short colpori (combined slit-and-pore apertures). [1]
  • PalDat places ragweed pollen in its 'small' size class, 10 to 25 micrometres. [1]

How many fit?

  • ≈ 81,000–110,000 × Pollen grain · diameter (hydrated grain) lined up end to end match the Human · height
  • ≈ 1.8–2.7 × Red blood cell · diameter lined up end to end match the Pollen grain · diameter (hydrated grain)

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

  • 1.8–2.7× A grain of ragweed pollen is about 1.8–2.7 times as wide as a red blood cell is across. See side by side
  • 1/3.5–4.4 The width of a human hair is about 3.5–4.4 times as wide as a grain of ragweed pollen. See side by side
  • 1/3.1–130 A grain of sand is about 3.1–130 times as wide as a grain of ragweed pollen. See side by side
  • 1/170–310 A black garden ant is about 170–310 times as long as a grain of ragweed pollen is wide. See side by side
  • 1/330–470 A grain of rice is about 330–470 times as long as a grain of ragweed pollen is wide. See side by side
  • 1/81,000–110,000 An average adult is about 81,000–110,000 times as tall as a grain of ragweed pollen is wide. See side by side

Factors compare the diameter (hydrated grain) of a grain of ragweed pollen 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

  • Pollen size varies greatly between plant species; this entry uses common ragweed as the example.
  • The diameter is for hydrated grains; dry grains shrink and change outline.
  • No source giving the mass of a single ragweed pollen grain was found, so mass is left out.

Sources

  1. PalDat - Palynological Database, Ambrosia artemisiifolia (diagnosis by S. Sam, H. Halbritter, H. Heigl; published 2020-12-17). Accessed 25 September 2026.

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