Metric Prefixes Table: Tera to Pico and Beyond
Metric prefixes are multipliers added to SI base units to indicate powers of 10. Once you know the prefixes, you can instantly understand any SI measurement — without looking it up. For example, 1 megawatt = 10⁶ watts; 1 nanosecond = 10⁻⁹ seconds. In 2022, four new prefixes were added, extending the system to 10⁻³⁰ and 10³⁰.
Memory Trick for Common Prefixes
For the ladder from kilo down to milli, use this mnemonic:
= Kilo · Hecto · Deka · Base · Deci · Centi · Milli
For larger prefixes beyond kilo: Mega · Giga · Tera · Peta · Exa (My Grandmother Taught People Excel).
Most-Used Prefixes in Science Education
| Prefix | Symbol | Power of 10 | Memory Aid |
|---|---|---|---|
| Tera | T | 10⁺12 | Trillion — Think: TeraByte |
| Giga | G | 10⁺9 | Billion — Think: GigaHz processor |
| Mega | M | 10⁺6 | Million — Think: Megapixel |
| Kilo | k | 10⁺3 | Thousand — Think: kilogram, kilometer |
| Centi | c | 10⁻2 | Hundredth — Think: centimeter, cent |
| Milli | m | 10⁻3 | Thousandth — Think: millimeter |
| Micro | μ | 10⁻6 | Millionth — Think: microscope |
| Nano | n | 10⁻9 | Billionth — Think: nanotechnology |
| Pico | p | 10⁻12 | Trillionth — Think: picofarad capacitor |
Complete SI Prefix Table (Quetta to Quecto)
All 25 official SI prefixes. The 4 newest (quetta, ronna, ronto, quecto) were added in November 2022.
| Prefix | Symbol | Power | Example / Context |
|---|---|---|---|
| Quetta | Q | 10^30 | ~mass of Earth in kg × 10⁵ |
| Ronna | R | 10^27 | ~mass of Earth in kg × 10² |
| Yotta | Y | 10^24 | ~mass of Earth: 6 × 10²⁴ kg |
| Zetta | Z | 10^21 | ~number of stars in universe |
| Exa | E | 10^18 | ~seconds since Big Bang: ~4 × 10¹⁷ |
| Peta | P | 10^15 | ~distance to nearest star in meters |
| Tera | T | 10^12 | 1 TB hard drive = 10¹² bytes |
| Giga | G | 10^9 | 1 GHz CPU = 10⁹ cycles/sec |
| Mega | M | 10^6 | 1 MW = 10⁶ watts |
| Kilo | k | 10^3 | 1 km = 1,000 m |
| Hecto | h | 10^2 | 1 hPa = 100 Pa (weather) |
| Deka | da | 10^1 | 1 dam = 10 m |
| (base) | — | 10^0 | 1 meter, 1 gram, 1 second |
| Deci | d | 10^-1 | 1 dL = 0.1 L |
| Centi | c | 10^-2 | 1 cm = 0.01 m |
| Milli | m | 10^-3 | 1 mm = 0.001 m |
| Micro | μ | 10^-6 | 1 μm = 10⁻⁶ m (bacterium) |
| Nano | n | 10^-9 | 1 ns = 10⁻⁹ s (computer ops) |
| Pico | p | 10^-12 | 1 pF = 10⁻¹² F (capacitor) |
| Femto | f | 10^-15 | 1 fm = 10⁻¹⁵ m (proton radius) |
| Atto | a | 10^-18 | attosecond laser pulses |
| Zepto | z | 10^-21 | charge of electron: ~160 zC |
| Yocto | y | 10^-24 | mass of proton: ~1.67 yg |
| Ronto | r | 10^-27 | subatomic physics |
| Quecto | q | 10^-30 | theoretical particle physics |
Frequently Asked Questions
What is the difference between kilo and mega?
Kilo (k) means 10³ = 1,000. Mega (M) means 10⁶ = 1,000,000. So 1 megabyte = 1,000 kilobytes. Each step up the standard prefix ladder multiplies by 1,000. Kilo → Mega → Giga → Tera, each 1,000 times larger than the previous.
How do I convert between metric prefixes?
Subtract the exponents of the two prefixes. For example, to convert kilometers to centimeters: kilo = 10³, centi = 10⁻². Difference: 3 − (−2) = 5. So 1 km = 10⁵ cm = 100,000 cm. Always convert to the base unit first if you're unsure: 1 km = 1,000 m; 1 cm = 0.01 m; so 1 km = 100,000 cm.
What are the newest SI prefixes?
In November 2022, the General Conference on Weights and Measures (CGPM) added four new prefixes: ronna (R, 10²⁷), quetta (Q, 10³⁰), ronto (r, 10⁻²⁷), and quecto (q, 10⁻³⁰). These were added because data storage and particle physics measurements were reaching the limits of the previous system.