About SI Prefixes Table

Reference table of all 20 SI (International System of Units) metric prefixes from yocto (10⁻²⁴) to yotta (10²⁴), each showing the prefix name, symbol, scientific notation factor, English name, and year of adoption. Includes search, filtering by scale (large/small/common), a built-in unit converter between any two prefixes, and CSV export. The converter handles base-unit inputs and converts through the ratio of prefix factors.

• 20 prefixes spanning 10⁻²⁴ to 10²⁴, with adoption years from 1795 to 1991
• Filter modes: All, Large (≥1), Small (<1), Common (kilo, mega, giga, milli, micro, nano)
• Search matches against prefix name, symbol, English name, and scientific notation string
• Unit converter: enter a value in one prefix, convert to another by dividing through base units
• CSV export with headers: Prefix, Symbol, Factor, Name, Adopted

Frequently Asked Questions

Does the table include the new quetta and ronna prefixes?

No. This table covers the 20 prefixes from yocto to yotta. The quetta (10³⁰), ronna (10²⁷), quecto (10⁻³⁰), and ronto (10⁻²⁷) prefixes adopted in 2022 are not yet included.

How does the unit converter work?

It multiplies the input value by the source prefix’s factor to get the base-unit value, then divides by the target prefix’s factor. For example, 5 km → ? mm: 5 × 10³ ÷ 10⁻³ = 5,000,000 mm.