A deeper look at where each current unit on this page comes from — the SI-prefixed units used in everyday electrical work, and the legacy CGS units still found in physics literature and older instrumentation.
SI-Prefixed Units (Nanoamperes through Megaamperes)
Amperes, Milliamperes, Microamperes, Nanoamperes, Centiamperes, Deciamperes, Kiloamperes, and Megaamperes are all the same underlying unit — the ampere — scaled by a power of ten. Current on a meter is almost always written in these SI prefixes. A milliamp is a thousandth of the ampere you typed, and a kiloamp is a thousand of them. Moving between those prefixes does not round, because each step is an exact power of ten.
Statampere (≈ 3.335641 × 10⁻¹⁰ A)
The statampere is the unit of electric current in the electrostatic (Gaussian/CGS) system, still used in some physics and electromagnetics literature. Its value in amperes is tied to the exact value of the speed of light constant, which is why different sources may round the statampere-to-ampere conversion very slightly differently.
Abampere and Biot (10 A)
The abampere is the unit of electric current in the electromagnetic (EMU/CGS) system. The biot is simply a later name for the exact same unit, adopted in some physics literature to honor Jean-Baptiste Biot. Both are defined as an exact power of ten relative to the ampere — 1 abA = 1 Bi = 10 A — so their conversions are always precise, with no rounding involved. They appear mainly in older laboratory instrumentation and legacy physics references.
| Unit |
Symbol |
Value in Amps |
Common Use |
| Nanoampere | nA | 1 × 10⁻⁹ | Photodiode / sensor leakage current |
| Microampere | µA | 1 × 10⁻⁶ | Standby / sleep-mode device draw |
| Milliampere | mA | 1 × 10⁻³ | LED and small-signal electronics |
| Centiampere | cA | 1 × 10⁻² | Rarely used outside academic exercises |
| Deciampere | dA | 1 × 10⁻¹ | Rarely used outside academic exercises |
| Ampere | A | 1 | SI base unit — breakers, meters, general use |
| Kiloampere | kA | 1 × 10³ | Fault current / short-circuit ratings |
| Megaampere | MA | 1 × 10⁶ | Lightning strikes, fusion / plasma research |
| Statampere | statA | ≈ 3.335641 × 10⁻¹⁰ | Physics / electrostatics (CGS-ESU) |
| Abampere | abA | 1 × 10¹ | Legacy lab instrumentation (CGS-EMU) |
| Biot | Bi | 1 × 10¹ | Same unit as abampere, alternate name (CGS-EMU) |
This guide is provided for educational and reference purposes. Always confirm measured current values against a properly calibrated meter or instrument before relying on them for any electrical work.
