Power Adapter Check
Check if you need a power adapter or voltage converter when traveling.
Select your home and destination countries to see plug types and voltage differences.
Power adapter compatibility depends on three electrical parameters that must all match (or be safely within range) to protect your device: voltage, current (amperage), and polarity.
Core compatibility rules:
Voltage (V): Must match exactly, or be within ±5% tolerance.
- Device rated 12V: adapter must output 12V (11.4V–12.6V acceptable)
- Overvoltage destroys components; undervoltage causes malfunction or no power
Current (A / mA): Adapter amperage must equal or exceed device requirement.
- Device needs 2A: any adapter rated 2A or more is safe
- Using a lower-rated adapter causes overheating and potential failure
Power (Watts): Calculated automatically from Ohm’s Law: P = V × I
Where:
- P = power in watts (W)
- V = voltage in volts (V)
- I = current in amperes (A)
Adapter wattage must meet or exceed device wattage: Adapter Power (W) = Adapter V × Adapter A Device Power (W) = Device V × Device A Safe if: Adapter Power ≥ Device Power AND Adapter V = Device V
What each variable means:
- Polarity — the “+” and “−” symbols or center-positive/center-negative markings on the barrel connector; reversed polarity will immediately damage or destroy a device
- DC vs AC — almost all consumer electronics use DC; AC adapters that supply DC have a rectifier built in and are labeled “DC output”
- Efficiency loss — adapters are typically 80–92% efficient; a 30W device may draw 33–37.5W from the wall
Reference: common adapter voltages by device type:
- 5V: USB devices, small fans, LED strips
- 9V: Pedal effects, some routers
- 12V: Routers, LED drivers, CCTV cameras
- 15V: Some laptops (older models)
- 19–20V: Most laptops
- 24V: Industrial equipment, some printers
- 48V: PoE network switches
Worked example: Laptop requires 19.5V, 3.33A. You have an adapter rated 19.5V, 4.74A.
- Device power = 19.5 × 3.33 = 64.9W
- Adapter power = 19.5 × 4.74 = 92.4W
- Voltage matches ✓ | Adapter amperage (4.74A) > device need (3.33A) ✓
- Result: compatible and safe — the device will only draw 3.33A; the adapter will run cooler than its rated maximum.
Never use an adapter with higher voltage — even 1V over spec can damage voltage-sensitive ICs permanently.