Cell size, units, and scale overview

Size comparisons and units

• Chicken egg vs frog egg: Chicken egg is much larger; frog eggs are small clusters of jelly (often described as grape-like clumps).
• Human egg size relative to a chicken egg: about the dot your pen makes in comparison to a chicken egg; roughly 100\,\,\mu\mathrm{m} across, which is 0.1\,\,\mathrm{mm}.
• Units emphasized:
  • A micrometer (µm) is a common size unit for cells.
  • The period at the end of a sentence is about the size of a micrometer (used as an intuitive reference for scale).
• Average cell size: about 20\,\,\mu\mathrm{m} across.
• Note: Cells vary enormously in appearance and function, but this gives a sense of scale for typical cells, including eggs (which are also cells).