HOW BIG
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Microcosm

Planck length: size, dimension and comparison

The adopted reference is about 1.62 × 10⁻³⁵ m.

theoretical length

A theoretical length reference, far smaller than a proton. A proton’s diameter is about 100 billion billion times this length.

A theoretical reference at the limits of our physical models.

Explore at this scale
Planck length, interpreted illustration
Interpreted illustration · dimension stated in the fact sheet.

What does this number measure?

A theoretical reference at the limits of our physical models. This length combines the reduced Planck constant, gravitation and the speed of light. It is not an experimentally demonstrated minimum size of space. The large interval between the proton and this scale contains no objects here whose size has been measured; that does not mean nothing exists at these scales.

Compare the stated dimensions

The comparison uses the number in each fact sheet: altitude, height, diameter, length or distance, depending on the reference. Two values in metres do not necessarily describe the same property.

Compare with Proton in the explorer →

Source and limitations

Catalogue order of magnitude; a source is provided, but this measurement has not been individually audited.

Planck length: an abstract pattern evoking a theoretical reference. This diagram depicts neither an observed object nor a proven structure of space.