Converting watts to amps and amps to watts

Here you will find the formulas to convert electric power in watts (W) to electric current in amps (A) and the common conversions of 110V and 240V used in most Western countries.

The formula

The formula for converting Watts to Amps is:

Watts = Amperes x Volts

The formula for converting Amps to Watts is:

Amperes = Watts/Volts

Safety warning!

Only use 80% of the circuit breaker capacity! Common conversions North American and other 110 volt countries.

[Grow] Lights 110V

• 1000W / 110V = 9.1 Ampere
• 600W / 110V = 5.4 Ampere
• 400W / 110V = 3.6 Ampere
• 250W / 110V = 2.3 Ampere

Circuits

• 10 Ampere x 110 Volt = 1100 Watts [80% safe usage is 880 Watts]
• 15 Ampere x 110 Volt = 1650 Watts [80% safe usage is 1320 Watts]
• 25 Ampere x 110 Volt = 2750 Watts [80% safe usage is 2200 Watts]
• 30 Ampere x 110 Volt = 3300 Watts [80% safe usage is 2640 Watts]

[Grow] Lights 240V

British Common wealth and other 240 volt countries

• 1000W / 240V = 4.1 Ampere
• 600W / 240V = 2.5 Ampere
• 400W / 240V = 1.7 Ampere
• 250W / 240V = 1.1 Ampere

Circuits

• 10 Ampere x 240 Volt = 2400 Watts [80% safe usage is 1920 Watts]
• 15 Ampere x 240 Volt = 3600 Watts [80% safe usage is 2880 Watts]
• 25 Ampere x 240 Volt = 6000 Watts [80% safe usage is 4800 Watts]
• 30 Ampere x 240 Volt = 7200 Watts [80% safe usage is 5760 Watts]

Note!

Remember that a circuit services more than one power outlet. A two outlet wall plug will use only one circuit. There will be more outlets on 240V systems per circuit than there will be in 110V systems.