Electrical Power Calculator
Enter any two known values to calculate the others. Uses P = V × I, P = V²/R, and P = I²R formulas.
Power Formulas
Common Appliance Power Ratings
Reference guide for typical electrical power consumption at standard voltages.
| Appliance | Power (W) | Typical Voltage | Current (A) |
|---|---|---|---|
| Phone Charger | 5-20 W | 5V USB | 1-4 A |
| LED Bulb | 5-15 W | 120/240V | 0.04-0.13 A |
| Laptop | 30-100 W | 19-20V DC | 1.5-5 A |
| Desktop PC | 200-500 W | 120/240V | 1.7-4.2 A |
| TV (55") | 80-150 W | 120/240V | 0.7-1.3 A |
| Refrigerator | 100-400 W | 120/240V | 0.8-3.3 A |
| Microwave | 600-1200 W | 120V | 5-10 A |
| Coffee Maker | 600-1200 W | 120V | 5-10 A |
| Space Heater | 750-1500 W | 120V | 6.3-12.5 A |
| Air Conditioner | 500-1500 W | 120/240V | 4-12.5 A |
About Electrical Power
Electrical power measures the rate at which electrical energy is transferred in a circuit. It's measured in watts (W), where 1 watt = 1 joule per second.
The fundamental relationship is P = V × I (Power = Voltage × Current). Combined with Ohm's Law (V = I × R), we can derive additional formulas like P = V²/R and P = I²R, allowing us to calculate any unknown value when two are known.
Practical tip: When sizing circuits or choosing components, always consider both the power rating and the current capacity. High current can cause overheating in undersized wires.
Privacy & Limitations
- All calculations run entirely in your browser -- nothing is sent to any server.
- Results are computed using standard formulas and should be verified for critical applications.
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Power Law Calculator FAQ
What is Power Law Calculator?
Power Law Calculator is a free engineering & physics tool that helps you Compute electrical power from voltage and current.
How do I use Power Law Calculator?
Enter your input values, review the calculated output, and adjust inputs until you reach the result you need. The result updates in your browser.
Is Power Law Calculator private?
Yes. Calculations run locally in your browser. Inputs are not uploaded to a server by default, and refreshing the page clears session data.
Does Power Law Calculator require an account or installation?
No. You can use this tool directly in your browser without sign-up or software installation.
How accurate are results from Power Law Calculator?
This tool applies standard formulas or deterministic processing logic for estimates. For medical, legal, tax, or investment decisions, verify with a qualified professional.
Can I save or share outputs from Power Law Calculator?
You can bookmark this page and copy outputs manually. Results are not persisted in your account and are typically not embedded in the URL.