What is the difference between mega (M) and milli (m)?

Mega (M) means one million, 10⁶, while milli (m) means one thousandth, 10⁻³. Note the capital M is a million and lowercase m is a thousandth — case matters.

Are the newest SI prefixes included?

Yes — the 2022 additions ronna (R, 10²⁷), quetta (Q, 10³⁰), ronto (r, 10⁻²⁷) and quecto (q, 10⁻³⁰) are all in the table.

Is anything uploaded?

No — this is a static reference table that runs entirely in your browser.

Metric Prefixes Reference

SI metric prefixes, full range

Every SI prefix from quetta (10³⁰) down to quecto (10⁻³⁰) — including the everyday ones (kilo, mega, giga, milli, micro, nano) and the 2022 additions (ronna, quetta, ronto, quecto). Each row gives the symbol, the power of ten and the full numeric factor.

Remember that case matters: capital M is mega (a million) while lowercase m is milli (a thousandth). Search by prefix, symbol or scale — everything runs in your browser.