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Current Unit Converter

Convert electric current between amperes, milliamperes, microamperes, nanoamperes, and picoamperes.

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Formula

1A=103mA=106muA=109nA=1012pA1 A = 10³ mA = 10⁶ mu A = 10⁹ nA = 10¹² pA

How It Works

This calculator converts between amperes, milliamperes, microamperes, nanoamperes, and picoamperes for electronics engineers, embedded developers, and power systems designers. Per SI Brochure (BIPM, 2019 redefinition), the ampere is defined by fixing elementary charge e = 1.602176634 × 10^-19 C exactly, making 1 A = 1 C/s = 6.241509074 × 10^18 electrons per second. Current ranges span 15 orders of magnitude: picoamperes for photodiode dark current (1-100 pA), nanoamperes for CMOS leakage (1-10 nA per gate at 7nm), microamperes for sleep-mode MCUs (0.5-10 uA), milliamperes for LEDs (5-20 mA), and amperes for motor drives (1-100 A). Battery life calculation: a 1000 mAh battery at 10 uA sleep current lasts 100,000 hours = 11.4 years theoretically.

Worked Example

Problem

An IoT sensor must operate 5 years on a 2000 mAh Li-SOCI2 battery. Calculate maximum average current budget including 10-second measurement bursts at 15 mA every hour.

Solution
  1. Total capacity: 2000 mAh = 2 Ah
  2. Target lifetime: 5 years = 43,800 hours
  3. Maximum average current: 2000 mAh / 43,800 h = 45.7 uA
  4. Burst consumption per hour: 15 mA × (10/3600) h = 0.0417 mAh
  5. Burst current averaged: 0.0417 mAh / 1 h = 41.7 uA
  6. Sleep budget: 45.7 - 41.7 = 4.0 uA maximum sleep current
  7. Component selection: MCU < 1 uA, regulator Iq < 1 uA, RTC < 0.5 uA, sensors < 1 uA - total 3.5 uA (within budget)

Practical Tips

  • ✓Battery life formula: hours = capacity_mAh / average_current_mA. For mixed-mode: I_avg = (I_active × t_active + I_sleep × t_sleep) / (t_active + t_sleep). Per JEDEC, report self-discharge separately (0.5-3%/month for Li-ion)
  • ✓LED current per IPC-2221: standard indicator 10-20 mA at 2.0 V (red) to 3.3 V (blue/white). High-efficiency LEDs achieve same brightness at 2-5 mA. Power = I × V_f, so 20 mA × 2 V = 40 mW per LED
  • ✓MCU GPIO limits per JEDEC: typically 8-25 mA per pin, 100-200 mA total package. Exceeding limits causes voltage droop (reduced logic margin) or permanent damage. Use external drivers for high-current loads

Common Mistakes

  • ✗Confusing mA (10^-3 A) with uA (10^-6 A) - they differ by 1000x. A device drawing 10 uA has 1000x lower power consumption than one drawing 10 mA. Check datasheet units carefully
  • ✗Ignoring inrush current which can be 5-10x steady-state - a 100 mA motor may draw 500 mA at startup, tripping a 200 mA fuse. Use slow-blow fuses or soft-start circuits
  • ✗Measuring nA-range currents with standard DMM - input burden voltage (200 mV typical) divided by DUT resistance creates measurement error. Use picoammeter or source-measure unit (SMU) for < 1 uA measurements

Frequently Asked Questions

Per manufacturer datasheets: STM32 = 20 mA/pin (max 120 mA total), ESP32 = 12 mA/pin source, 28 mA sink (max 200 mA total), AVR = 20 mA/pin (max 200 mA total). Always check both per-pin and total current limits. IOL and IOH specifications define actual capability.
For 1 uA - 1 mA: use DMM on uA range (burden voltage ~200 mV). For < 1 uA: use picoammeter or transimpedance amplifier (TIA). Shunt resistor method: V = I × R, so 1 uA through 1 Mohm = 1 V (easily measured). Keysight B2902A SMU measures down to 100 fA with 10 aA resolution.
Quiescent current (Iq) is the current an IC draws with no load, representing internal bias and operating overhead. Per datasheets: LDO regulators 1 uA - 1 mA, DC-DC converters 5 uA - 500 uA, op-amps 0.5 uA - 10 mA. Ultra-low-power LDOs (TPS7A02) achieve 25 nA Iq for IoT battery applications.
Dark current arises from thermally generated electron-hole pairs in the depletion region per Shockley diode equation. Typical values at 25 C: silicon PIN 0.1-10 nA, InGaAs 1-100 nA, avalanche photodiodes 0.1-1 nA. Dark current doubles every 8-10 C per Arrhenius relationship, limiting low-light detection SNR.

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