Electric Current Converter

Electric current is the rate of charge flow, measured in amperes (A). Home wall sockets deliver 15 or 20 A at 120 V (US) or 10-16 A at 230 V (EU). A phone charger pulls ~1-2 A. Arc welders draw 100+ A. A bolt of lightning peaks at 30,000 A for microseconds.

The ampere (A) is an SI base unit, redefined in 2019 as the current corresponding to 1/(1.602176634 × 10⁻¹⁹) elementary charges per second. Subunits: milliampere (mA), microampere (µA), nanoampere (nA). A TTL logic signal is ~1 mA; a relay coil might pull 50-100 mA; a laptop charger at full load is ~3 A at 20 V.

Milliampere to ampere: divide by 1,000. Ohm's law: voltage = current × resistance. Power (W) = current (A) × voltage (V).

• Ampere (A)
• Milliampere (mA)
• Microampere (µA)
• Nanoampere (nA)
• Kiloampere (kA)
• Abampere (aA)
• Statampere (esu)
• Biot
• e/hour

• mA vs A. Thousand-fold difference. A USB power supply rated '2A' delivers 2,000 mA; an LED rated 20 mA draws 100× less.
• Continuous vs peak current. A capacitor's inrush can be 10-100× its steady current for microseconds.
• AC vs DC current. Wall outlets are AC; batteries are DC. Meters and fuses are rated for one or the other or both.

• LED indicator: 5-20 mA.
• Phone charging: 1-2 A at 5 V USB (5-10 W).
• Laptop charging: 2-3 A at 20 V (40-60 W).
• Household wall socket (US): 15 or 20 A breaker at 120 V.
• Microwave oven: 10-12 A at 120 V.
• Electric dryer (US): 30 A at 240 V.
• EV Level 2 home charger: 30-50 A at 240 V.
• Tesla Supercharger V3: 600+ A at battery level.
• Arc welder: 100-400 A.
• Lightning strike: 30,000 A peak.

• For wiring, current determines wire gauge. 15 A needs 14 AWG minimum; 20 A needs 12 AWG; 30 A needs 10 AWG.
• For power supplies, never exceed the rated continuous current. Fires start where insulation overheats.

Related: Electric Charge Converter · Electrical Resistance Converter · Power Converter.