Milliampere to Nanoampere
mA
nA
Conversion History
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Quick Reference Table (Milliampere to Nanoampere)
| Milliampere (mA) | Nanoampere (nA) |
|---|---|
| 1 | 1,000,000 |
| 5 | 5,000,000 |
| 20 | 20,000,000 |
| 100 | 100,000,000 |
| 500 | 500,000,000 |
| 1,000 | 1,000,000,000 |
| 2,000 | 2,000,000,000 |
About Milliampere (mA)
The milliampere (mA) equals one thousandth of an ampere (10⁻³ A) and is the practical unit for most consumer electronics and lighting circuits. USB 2.0 ports supply up to 500 mA; USB-C Power Delivery can reach 5,000 mA (5 A). A standard 5 mm indicator LED operates at 10–20 mA; mid-power LED drivers supply 100–350 mA. Human perception of electric shock begins near 1 mA; currents above 10 mA cause involuntary muscle contraction, and above 100 mA can be lethal. Wireless sensors, earphones, and small motors typically draw single-digit to low-hundreds of milliamperes.
A USB 2.0 port provides up to 500 mA for charging. A standard 5 mm indicator LED operates at around 20 mA.
About Nanoampere (nA)
The nanoampere (nA) equals one billionth of an ampere (10⁻⁹ A) and is used for the smallest measurable electrical currents in precision instrumentation and low-power electronics. Electrochemical biosensors detecting glucose or DNA generate signals in the nanoampere range; implantable devices are designed to draw only a few nanoamperes in sleep states to extend battery life by years. Junction leakage currents in CMOS transistors and reverse-bias diode currents are also measured in nanoamperes. In electrochemistry, nanoampere-resolution galvanostat equipment is standard for corrosion studies and thin-film deposition research.
A glucose biosensor strip draws approximately 100–500 nA during a measurement. A low-power microcontroller in deep sleep typically consumes 1–100 nA.
Milliampere – Frequently Asked Questions
How many milliamps is dangerous to a human?
The danger thresholds for 50/60 Hz AC are roughly: 1 mA (tingling), 10–20 mA (muscle lock — you cannot let go), 75–100 mA (ventricular fibrillation), and 200+ mA (cardiac arrest and burns). DC is somewhat less dangerous at the same current. Duration matters enormously — 100 mA for 1 second is more lethal than 100 mA for 10 ms.
Why is my phone charger rated in milliamps when it charges at 2 amps?
Battery capacity is rated in milliampere-hours (mAh), not milliamps. A 4,000 mAh battery holds 4,000 mA for one hour (or 2,000 mA for two hours). The charger delivers 2 A (2,000 mA) of current, and it takes about 2 hours to fill that 4,000 mAh battery from empty.
What is the milliamp draw of common household items?
A wireless earbud draws 5–15 mA during playback. A TV remote uses about 10 mA when pressing a button. An LED nightlight consumes 20–50 mA. A smoke detector in standby draws 10–30 μA (0.01–0.03 mA) — so low it runs on a 9V battery for years.
Why do LED specifications always mention 20 mA?
Standard 5 mm indicator LEDs were designed around a 20 mA operating point — bright enough to see clearly, low enough to avoid overheating the tiny die. All datasheet specs (luminous intensity, color, forward voltage) are measured at this "test current." High-power LEDs use 350 mA or 700 mA as their reference instead.
How does milliamp-hour (mAh) relate to milliamp (mA)?
Milliamp-hours measure charge capacity; milliamps measure current flow rate. A 2,000 mAh battery can deliver 2,000 mA for 1 hour, or 200 mA for 10 hours, or 20 mA for 100 hours — current times time equals capacity. Dividing mAh by mA gives approximate runtime in hours.
Nanoampere – Frequently Asked Questions
Why does my microcontroller datasheet list nanoampere sleep currents?
Chip designers optimize deep-sleep modes to leak only 1–100 nA so a coin cell battery (225 mAh) can power the device for 5–10 years without replacement. Every nanoampere matters in IoT sensors deployed in remote locations where battery swaps are impractical or impossible.
Can you actually measure a single nanoampere of current?
Yes — picoammeters and source-measure units (SMUs) from Keithley or Keysight resolve currents down to 0.01 nA. The trick is shielding: at nanoampere levels, even humidity on a PCB trace or triboelectric effects from cable movement can introduce errors larger than the signal itself.
What biological processes produce nanoampere-level currents?
Individual ion channels in cell membranes pass about 2–10 picoamperes each, but clusters of channels in a patch-clamp experiment produce nanoampere signals. Electrochemical glucose sensors generate 50–500 nA proportional to blood sugar levels. Neural signal electrodes also detect nA-scale biocurrents.
How does nanoampere leakage current affect circuit design?
At nanoampere levels, leakage through PCB substrates, capacitor dielectrics, and transistor junctions becomes significant. High-impedance analog circuits must use guarded traces, Teflon standoffs, and low-leakage components. A fingerprint on a circuit board can introduce 1–10 nA of leakage from moisture absorption.
How many electrons per second is one nanoampere?
One nanoampere is about 6.24 billion electrons per second (6.24 × 10⁹ e/s). That sounds like a lot, but it is literally a billionth of the electron flow in a one-ampere current. Counting individual electrons at this rate is the basis of quantum current standards being developed at national metrology labs.