Charger Power Calculator
Calculate charger power in watts (W) from voltage (V) and current (A). Enter the charger voltage and current to estimate its maximum electrical power output.
Power (W) = Voltage (V) × Current (A)
How to Calculate Charger Wattage
Charger wattage tells you how much electrical power a charger can provide under a particular voltage and current output. The basic calculation is simple:
Power (W) = Voltage (V) × Current (A)
For example, a charger rated at 20V and 3A can provide:
20V × 3A = 60W
Therefore, a 20V 3A output has a maximum electrical power of approximately 60 watts under those conditions.
Charger Wattage Examples
| Voltage | Current | Power |
|---|---|---|
| 5V | 2A | 10W |
| 9V | 2A | 18W |
| 12V | 2A | 24W |
| 15V | 3A | 45W |
| 20V | 3A | 60W |
| 20V | 5A | 100W |
| 20V | 7A | 140W |
What Is Charger Wattage?
Charger wattage is the amount of electrical power available from a charger's output. It is measured in watts (W). A charger with a higher wattage can potentially deliver more power, but the connected device determines how much power it actually accepts.
For example, a 100W charger does not automatically force 100W into every phone. The phone, charger, charging protocol, cable, and charging conditions all affect the actual charging power.
How Many Watts Is a USB-C Charger?
USB-C chargers can support many different power levels. Common outputs include 18W, 20W, 30W, 45W, 65W, 100W and higher-power USB Power Delivery chargers.
For USB-C Power Delivery, the charger may offer several voltage and current combinations rather than one fixed output. For example, a charger may provide 20V at 5A for a maximum of 100W.
The actual charging power depends on the negotiated charging profile and the capabilities of the device and cable.
How to Calculate USB-C Charger Power
To calculate the power of a USB-C charging profile, multiply its voltage by its current.
For example:
20V × 5A = 100W
This means a 20V 5A charging profile can provide up to approximately 100W of electrical power when the charger, device, cable, and charging protocol all support that level.
Does a Higher Wattage Charger Charge Faster?
Not always. A higher-wattage charger can provide more power, but the device must support the required charging power. If a phone supports a maximum charging input below the charger's rating, it will normally draw only the power it is designed to accept.
Charging speed can also change as the battery fills. Many devices reduce charging power at higher battery levels to control heat and protect the battery.
Charger, Device and Cable Compatibility
Maximum charging power is not determined by the charger alone. The charger, device, cable, and charging protocol must work together.
- Charger: Must support the required voltage and current.
- Device: Determines how much power it can accept.
- Cable: Must support the required current and charging standard.
- Protocol: USB Power Delivery and other charging systems determine compatible charging profiles.
Common Charger Wattages
Different devices commonly use different charging power levels. Smaller phones may use relatively low power, while tablets, laptops and other larger devices may require higher-wattage chargers.
Common charger ratings include:
- 10W chargers
- 18W chargers
- 20W chargers
- 30W chargers
- 45W chargers
- 65W chargers
- 100W chargers
- 140W chargers
Charger Power Calculator FAQ
How do I calculate watts from volts and amps?
Multiply voltage by current. For example, 20V × 3A equals 60W.
How many watts is 5V 2A?
A 5V 2A output provides up to approximately 10W.
How many watts is 9V 2A?
A 9V 2A output provides up to approximately 18W.
How many watts is 20V 3A?
A 20V 3A output provides up to approximately 60W.
How many watts is 20V 5A?
A 20V 5A output provides up to approximately 100W.
How many watts is 20V 7A?
A 20V 7A output provides up to approximately 140W.
Can a 100W charger charge a phone?
Yes, if the charger is compatible with the phone's charging standard. The phone will normally draw only the amount of power it supports rather than automatically receiving the full 100W.
Does the cable affect charging power?
Yes. A USB-C cable must support the required charging current and capabilities. Some higher-power USB-C charging applications also require an electronically marked cable with the appropriate current rating.
Charger Power Calculator
Calculate charger power in watts (W) from voltage (V) and current (A). Enter the charger voltage and current to estimate its maximum electrical power output.
Power (W) = Voltage (V) × Current (A)
How to Calculate Charger Wattage
Charger wattage tells you how much electrical power a charger can provide under a particular voltage and current output. The basic calculation is simple:
Power (W) = Voltage (V) × Current (A)
For example, a charger rated at 20V and 3A can provide:
20V × 3A = 60W
Therefore, a 20V 3A output has a maximum electrical power of approximately 60 watts under those conditions.
Charger Wattage Examples
| Voltage | Current | Power |
|---|---|---|
| 5V | 2A | 10W |
| 9V | 2A | 18W |
| 12V | 2A | 24W |
| 15V | 3A | 45W |
| 20V | 3A | 60W |
| 20V | 5A | 100W |
| 20V | 7A | 140W |
What Is Charger Wattage?
Charger wattage is the amount of electrical power available from a charger's output. It is measured in watts (W). A charger with a higher wattage can potentially deliver more power, but the connected device determines how much power it actually accepts.
For example, a 100W charger does not automatically force 100W into every phone. The phone, charger, charging protocol, cable, and charging conditions all affect the actual charging power.
How Many Watts Is a USB-C Charger?
USB-C chargers can support many different power levels. Common outputs include 18W, 20W, 30W, 45W, 65W, 100W and higher-power USB Power Delivery chargers.
For USB-C Power Delivery, the charger may offer several voltage and current combinations rather than one fixed output. For example, a charger may provide 20V at 5A for a maximum of 100W.
The actual charging power depends on the negotiated charging profile and the capabilities of the device and cable.
How to Calculate USB-C Charger Power
To calculate the power of a USB-C charging profile, multiply its voltage by its current.
For example:
20V × 5A = 100W
This means a 20V 5A charging profile can provide up to approximately 100W of electrical power when the charger, device, cable, and charging protocol all support that level.
Does a Higher Wattage Charger Charge Faster?
Not always. A higher-wattage charger can provide more power, but the device must support the required charging power. If a phone supports a maximum charging input below the charger's rating, it will normally draw only the power it is designed to accept.
Charging speed can also change as the battery fills. Many devices reduce charging power at higher battery levels to control heat and protect the battery.
Charger, Device and Cable Compatibility
Maximum charging power is not determined by the charger alone. The charger, device, cable, and charging protocol must work together.
- Charger: Must support the required voltage and current.
- Device: Determines how much power it can accept.
- Cable: Must support the required current and charging standard.
- Protocol: USB Power Delivery and other charging systems determine compatible charging profiles.
Common Charger Wattages
Different devices commonly use different charging power levels. Smaller phones may use relatively low power, while tablets, laptops and other larger devices may require higher-wattage chargers.
Common charger ratings include:
- 10W chargers
- 18W chargers
- 20W chargers
- 30W chargers
- 45W chargers
- 65W chargers
- 100W chargers
- 140W chargers
Charger Power Calculator FAQ
How do I calculate watts from volts and amps?
Multiply voltage by current. For example, 20V × 3A equals 60W.
How many watts is 5V 2A?
A 5V 2A output provides up to approximately 10W.
How many watts is 9V 2A?
A 9V 2A output provides up to approximately 18W.
How many watts is 20V 3A?
A 20V 3A output provides up to approximately 60W.
How many watts is 20V 5A?
A 20V 5A output provides up to approximately 100W.
How many watts is 20V 7A?
A 20V 7A output provides up to approximately 140W.
Can a 100W charger charge a phone?
Yes, if the charger is compatible with the phone's charging standard. The phone will normally draw only the amount of power it supports rather than automatically receiving the full 100W.
Does the cable affect charging power?
Yes. A USB-C cable must support the required charging current and capabilities. Some higher-power USB-C charging applications also require an electronically marked cable with the appropriate current rating.