How do I convert between SI prefixes?

Count the difference in powers of 10, then move the decimal point. Kilo to milli: 10³ to 10⁻³ = 6 steps = move decimal 6 places. 5 km = 5,000,000 mm. Micro to nano: 1 step = 3 places. 5 μm = 5,000 nm.

Why are some prefixes missing (like hecto)?

Hecto (h, 100), deca (da, 10), deci (d, 0.1), and centi (c, 0.01) exist but are less common. They don't follow the powers-of-1000 pattern used by other prefixes. Centimeter and hectare are notable exceptions that remain in common use.

What's the difference between K and k?

Lowercase k means kilo (10³ = 1000). Capital K is for Kelvin (temperature). In computing, K sometimes informally means 1024 (2¹⁰), though IEC recommends Ki (kibi) for binary prefixes. Watch for context—1 KB may mean 1000 or 1024 bytes depending on usage.

بادئات SI Converter

About SI Prefix Conversion

SI prefixes are standardized multipliers that scale units by powers of 10. They allow convenient expression of very large or very small quantities without writing many zeros. From quetta (10³⁰) to quecto (10⁻³⁰), these prefixes now cover 60 orders of magnitude—the range from subatomic particles to the observable universe. The prefixes were extended in 2022 with ronna/ronto and quetta/quecto to accommodate growing data quantities and advancing science.

Understanding SI prefixes is fundamental to science, engineering, and everyday technology. We routinely use kilobytes, milligrams, gigahertz, and nanoseconds—all using SI prefixes to scale base units. Most prefixes step by factors of 1000 (10³), making conversions straightforward: each step moves the decimal three places. The few exceptions (hecto, deca, deci, centi) exist for historical reasons but are less commonly used.

Our converter helps translate between any SI prefix magnitudes for any unit.

Common SI Prefix Relationships

Prefix	Symbol	Factor	Example Use
tera	T	10¹²	Terabyte (TB)
giga	G	10⁹	Gigahertz (GHz)
mega	M	10⁶	Megapixel (MP)
kilo	k	10³	Kilometer (km)
milli	m	10⁻³	Millimeter (mm)
micro	μ	10⁻⁶	Microgram (μg)
nano	n	10⁻⁹	Nanometer (nm)
pico	p	10⁻¹²	Picofarad (pF)

SI Prefix Reference

Everyday prefixes: kilo (k, 10³ = thousand), mega (M, 10⁶ = million), giga (G, 10⁹ = billion), milli (m, 10⁻³ = thousandth), micro (μ, 10⁻⁶ = millionth). These cover most consumer and general engineering applications—kilometers, megapixels, gigabytes, milligrams, microseconds.

Scientific prefixes: nano (n, 10⁻⁹) for atomic/chip dimensions and nanotechnology, pico (p, 10⁻¹²) for capacitors and ultrafast physics, femto (f, 10⁻¹⁵) for nuclear and femtosecond lasers, atto (a, 10⁻¹⁸) for attosecond spectroscopy. On the large side: tera (T, 10¹²) for hard drives and network bandwidth, peta (P, 10¹⁵) for supercomputer operations, exa (E, 10¹⁸) for global data storage.

Extreme prefixes: yotta (Y, 10²⁴) and yocto (y, 10⁻²⁴) approach physical limits—yotta is about Earth's mass in grams. In 2022, the BIPM added ronna (R, 10²⁷), quetta (Q, 10³⁰), ronto (r, 10⁻²⁷), and quecto (q, 10⁻³⁰) to handle growing data quantities and ensure prefixes exist before informal alternatives emerge.

Intermediate prefixes: hecto (h, 10²), deca (da, 10¹), deci (d, 10⁻¹), centi (c, 10⁻²) don't follow the ×1000 pattern. They survive mainly in specific applications: hectare, decibel, centimeter, deciliter. Modern scientific usage typically skips them in favor of the standard prefixes.