Order of Magnitude
An exponential estimate of the size of a quantity, expressed as the power of ten closest to the numerical value.
Governing formula
10^n
SI unit
Dimensionless
In depth
Orders of magnitude provide rapid comparative scale checks (Fermi estimates) without requiring detailed computation. A factor of 10 difference represents one order of magnitude.
Examples in the real world
The observable universe diameter (~10²⁶ m) is 41 orders of magnitude larger than a proton radius (~10⁻¹⁵ m).