Amps Volts Watts Calculator

Enter known electrical values and solve missing units instantly. Check AC, DC, resistance, and energy. Export results for quick sharing and safer project records.

Calculator Form

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Formula Used

DC watts: W = V × A

DC amps: A = W ÷ V

DC volts: V = W ÷ A

Ohm’s law: V = A × Ω

Resistance: Ω = V ÷ A

Single phase watts: W = V × A × PF

Three phase watts: W = √3 × V × A × PF

Energy: kWh = W × Hours ÷ 1000

Cost: Cost = kWh × Rate

How to Use This Calculator

Select the calculation type first. Enter the known values in the matching fields. Leave unused fields unchanged. Use power factor for AC loads. Use 1 for DC or resistive loads. Press the calculate button. The answer appears above the form and below the header. Use the export buttons to save the result.

Example Data Table

Use Case Volts Amps Power Factor Formula Result
DC light strip 12 V 5 A 1 W = V × A 60 W
Single phase tool 120 V 10 A 0.90 W = V × A × PF 1080 W
Three phase motor 400 V 20 A 0.85 W = √3 × V × A × PF 11778.46 W
Energy estimate - - - kWh = W × h ÷ 1000 1.2 kWh from 1200 W for 1 h

Understanding Electrical Power

An amps volts watts calculator helps you connect current, pressure, and power. Amps show the flow of electric charge. Volts show the electrical pressure that pushes that charge. Watts show the useful power delivered by the circuit. These values are linked, so one missing value can be found when enough related values are known.

Why This Calculator Helps

Electrical planning often needs quick checks before buying parts. A small device may list watts only. A battery may list volts only. A motor label may include current and power factor. This tool brings those details into one place. It supports direct current, single phase alternating current, three phase loads, resistance checks, energy use, and cost estimates. It also gives CSV and PDF export options for records.

Main Calculation Ideas

For direct current, watts equal volts multiplied by amps. For alternating current, power factor reduces real power. Single phase power uses volts, amps, and power factor. Three phase power also uses the square root of three. Resistance calculations follow Ohm’s law. Energy cost uses watts, hours, and price per kilowatt hour. These formulas are common starting points for simple estimates.

Practical Use Cases

Use the calculator to size a power supply. Check the current drawn by a heater. Estimate battery load. Review cable load before choosing protection. Compare single phase and three phase machines. Estimate daily energy use from appliance watts and run time. The results help organize basic design notes. They do not replace local code checks or professional review.

Good Input Habits

Use rated values from labels when possible. Enter positive numbers only. For power factor, use a value between zero and one. Use one for direct current or purely resistive loads. Keep voltage type and phase clear. Round results based on your work. Leave extra capacity for real installations. Heat, cable length, starting surge, and safety rules can change final choices.

Reading The Results

The main result appears first. Supporting values appear below it. Notes explain which formula was used. Units stay visible, so the answer is easier to check. Copy the numbers into your worksheet. Then export the summary when you need a saved record or a client note. Keep source labels with saved calculations.

FAQs

What is the basic watts formula?

For direct current, watts equal volts multiplied by amps. The formula is W = V × A. It works well for simple DC loads and resistive examples.

How do I calculate amps from watts?

Divide watts by volts. For AC loads, also divide by power factor when real power is used. The formula is A = W ÷ (V × PF).

What does power factor mean?

Power factor shows how efficiently apparent power becomes real power. A value of 1 is ideal. Motors and inductive loads often have lower values.

Can this calculator handle three phase power?

Yes. Choose a three phase option. Enter line voltage, current, and power factor. The calculator uses the square root of three in the formula.

What is the formula for resistance?

Resistance equals volts divided by amps. The formula is Ω = V ÷ A. This comes from Ohm’s law and needs positive input values.

How is energy cost estimated?

The calculator converts watts and hours into kilowatt hours. It then multiplies that value by your entered rate per kilowatt hour.

Should I use AC or DC formulas?

Use DC formulas for batteries and direct current circuits. Use AC formulas for household, shop, and motor loads where power factor may matter.

Are these results safe for final wiring design?

Use the results for estimates and planning. Final wiring should follow local codes, device ratings, breaker rules, heat limits, and professional guidance.

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Important Note: All the Calculators listed in this site are for educational purpose only and we do not guarentee the accuracy of results. Please do consult with other sources as well.