Aisha K.
Mar 12, 2026
Clean layout and the results update instantly. Exactly what I needed for a quick planning check.
Unit Converters
Electricity Usage: Watts and Hours to kWh
kWh = W × hours ÷ 1,000.
kWh = watts × hours / 1,000. A 60 W bulb for 5 hours is 0.3 kWh. Nameplate watts on a fridge are not the same as the compressor’s duty cycle.
Watts
W → kWh
0.3 kWh
Nameplate watts × hours. A fridge compressor does not run the whole hour.
- Power
- 60 W
- Hours
- 5
Plain-English guide
Terms & how it works
Confused by a field? Read the short definitions here while you use the tool.
Watts
The “Watts” value used in this tool’s formula. Adjust it to see results update live.
Hours
The “Hours” value used in this tool’s formula. Adjust it to see results update live.
How this calculator works
kWh = watts × hours / 1,000. A 60 W bulb for 5 hours is 0.3 kWh. Nameplate watts on a fridge are not the same as the compressor’s duty cycle. kWh = W × hours ÷ 1,000. Example: 1500 W kettle × 0.1 h → 0.15 kWh. 10 W router × 24 h → 0.24 kWh.
kWh = W × hours ÷ 1,000.
Example: 1500 W kettle × 0.1 h → 0.15 kWh. 10 W router × 24 h → 0.24 kWh.
When to use this Watts and Hours to kWh
Common use cases
- kWh = watts × hours / 1,000. A 60 W bulb for 5 hours is 0.3 kWh. Nameplate watts on a fridge are not the same as the compressor’s duty cycle.
- Sanity-check with this case: 1500 W kettle × 0.1 h → 0.15 kWh. 10 W router × 24 h → 0.24 kWh.
- The relationship is: kWh = W × hours ÷ 1,000.
Localized examples
- Unit Converters: the example on this page uses the same formula as the widget.
What you get
- Fields: Watts, Hours
- kWh = W × hours ÷ 1,000.
- Example on the page: 1500 W kettle × 0.1 h → 0.15 kWh. 10 W router × 24 h → 0.24 kWh.
How to Convert Watts and Hours to kWh Step-by-Step
- 1Enter Watts, Hours. Use the values you have, not a catalog average, unless that is all you know.
- 2kWh = W × hours ÷ 1,000.
- 3Worked case: 1500 W kettle × 0.1 h → 0.15 kWh. 10 W router × 24 h → 0.24 kWh.
- 4Check which dictionary the other person is using — US or UK, decimal or 1,024 — then trust the number.
Governing formula
kWh = W × hours ÷ 1,000.
1500 W kettle × 0.1 h → 0.15 kWh. 10 W router × 24 h → 0.24 kWh.
Example: set Watts = 60, Hours = 5, then read the result.
Variable definitions
- value
Watts
The “Watts” field. Default 60; typical range 0–10000.
- hours
Hours
The “Hours” field. Default 5; typical range 0–24.
- The conversion (kWh = W × hours ÷ 1,000.) does not pick US vs UK gallons, SI vs binary megabytes, or Mach at altitude for you. Read the footnote on the page.
- Nothing here is uploaded for the calculation itself.
Frequently Asked Questions
Use the standby watts, not the cooking watts.
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Unit Converters
- Solar Panel Daily kWhkWh/day ≈ (array W / 1000) × peak sun hours. A 400 W panel in 4.5 PSH is 1.8 kWh before dirt, heat, and inverter loss (often 0.75–0.85). NREL sun-hour maps beat a guess.
- Appliance Running CostCost = watts × hours / 1000 × $/kWh. A 1,500 W space heater for 4 hours at $0.16/kWh is $0.96. The supply rate on the bill is the one that matters, not a national average.
- BTU to kWhUS furnaces and AC still speak BTU. Electricity speaks kWh. Divide BTU by 3,412. 12,000 BTU/h is a “1 ton” of cooling and 3.52 kW if it ran an hour — note the /h: that is power. This field is energy (BTU, not BTU/h).
- kWh to MegajoulesYour electric bill is in kWh. Physics problems want joules. 1 kWh = 3.6 MJ exactly (1,000 W × 3,600 s). A 30 kWh EV pack is 108 MJ. That is energy stored, not how far you will get in the rain.
- Days to HoursMultiply days by 24. A “two-day” shipping promise is 48 hours if they meant calendar days, and something shadier if they meant business days. This page does not skip Sundays.
- dBm to WattsP(W) = 10^((dBm − 30)/10). 0 dBm is 1 mW. 30 dBm is 1 W. Wi-Fi EIRP limits are a regulator’s problem; this is just the log.
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Community
Reviews & Ratings
See what others think about this tool, then leave your own rating to help improve CalculioHub.
4.8
out of 5.0
4 reviews
Daniel R.
Feb 28, 2026
Very usable on mobile. Would love a save/export option later, but the math feels solid.
Priya S.
Feb 3, 2026
The FAQ section answered my questions before I even had to search. Smooth dark mode too.
Marcus L.
Jan 19, 2026
Simple inputs, clear outputs. This replaced three bookmarks I used to juggle.
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