Enter voltage and current to get electrical power in watts — plus the daily energy in kWh at your usage hours.
What Is Electrical Power?
An electrical power calculator applies P = V × I: 230 V × 5 A = 1,150.00 W; over 8 hours = 9.20 kWh per day. Watts are the rate, kilowatt-hours the total energy the meter bills. This is the DC/resistive case — for AC motors, power factor (< 1) reduces real power, noted below.
How to Use
- Enter the voltage.
- Enter the current.
- Enter hours per day.
- Click “Calculate Power”.
Formula
P = V × I. Energy = P × hours ÷ 1,000 (kWh).
Worked Example
230 V × 5 A = 1,150.00 W. 8 h/day → 9.20 kWh/day.
How It Works, In Plain Words
Electrical power is the product of two things you can read off a rating plate or measure: voltage, the electrical pressure pushing current around the circuit, and current, the flow itself, measured in amps. Multiply them and you get power in watts: P = V × I. In the worked example, 230 V × 5 A gives 1,150.00 W — that is how hard the load is working at any instant while it runs. The third input, hours used per day, turns that rate into energy: Energy = P × hours ÷ 1,000, which converts watt-hours into the kilowatt-hours your meter counts. At 8 hours a day, the example load uses 9.20 kWh daily.
One honest limit, stated on this page from the start: the simple multiplication is exact for DC and for resistive AC loads such as heaters. For AC motors and other inductive loads, power factor enters the picture — real power is V × I × PF, and with PF below 1 the real power is less than the plain product suggests. The tool keeps the straightforward single-phase and DC case, and says so, rather than hiding a correction you did not ask for.
Real-World Uses
A homeowner pricing up a winter heater reads the voltage and current on its plate, runs the tool, and learns both its wattage and what running it 8 hours a day adds in kWh — the figure that actually reaches the bill. Someone setting up a workshop checks whether a machine’s draw fits the circuit they plan to use, one of the sizing jobs this page is built for, before anything is plugged in. And a tenant who suspects one appliance of inflating the electricity bill tests it in seconds: enter its volts and amps, set realistic daily hours, and the kWh answer shows whether the suspicion holds up.
Benefits
- Watts and daily kWh together
- The rate-vs-energy distinction explained
- Power-factor note for AC motors
- Useful for sizing circuits and estimating bills
Features of Our Tool
- Instant results in your browser
- No sign-up, no download, 100% free
- Works on mobile, tablet and desktop
- Clear step-by-step explanation below the tool
- Private — your entries never leave your device.
Common Mistakes
- Confusing watts (rate) with kWh (energy)
- Ignoring power factor on inductive loads (motors, ballasts)
- Forgetting 230 V vs 120 V regions when reading specs.
Common Mistakes to Avoid
The classic error is treating watts as if they were the bill: watts are only the rate, and it is the kilowatt-hours — watts multiplied by hours, divided by 1,000 — that the meter charges for, which is why the hours input matters as much as the other two. Next, do not take V × I at face value for motors and ballasts: with power factor below 1, real power is lower than the product. Watch the voltage region too — a specification written for 120 V regions misleads when your supply is 230 V. And treat results as planning figures: actual wiring and circuit work belongs to a qualified electrician.
FAQ
How many watts is 230 V × 5 A?
1,150.00 W.
What is the difference between W and kWh?
Watts measure power (rate); kWh measure energy (power × time) — the meter bills kWh.
What is power factor?
For AC motors, real power = V × I × PF; PF < 1 means less real power than V × I.
How much energy per day?
1,150 W × 8 h = 9.20 kWh here.
Can I use it for 3-phase?
No — 3-phase needs √3 × V × I × PF; this tool is single-phase/DC.
Why does the tool ask for hours per day?
Because watts alone do not make a bill. Energy — the thing the meter charges for — is power multiplied by time, so the tool applies Energy = P × hours ÷ 1,000 to turn your wattage into kilowatt-hours per day: the example load’s 1,150 W over 8 hours comes to 9.20 kWh.
Does this tool work for DC circuits?
Yes — P = V × I is exactly the DC and resistive case this page describes. It is AC motors and similar inductive loads where a power factor below 1 makes real power less than V × I, and three-phase supplies need a different formula again, as the question above explains.