Electrical energy
kWh
Energy consumed over the entered operating time.
Electricity · Essential electrical quantities
Electricity cost calculator — power, time, kWh and cost
Calculate energy use from power and operating time, then apply your tariff per kWh. The cost result uses the same currency as the tariff you enter.
Created v1.0
By Thibaut Grzelak, Mechanical Analysis Engineer
02
Results
Estimated cost
Cost in the same currency unit used for the tariff.
Relation and numerical substitution
E = P · t ; C = E · c—
Power and tariff are nonnegative; operating time is strictly positive. Power is treated as constant or as the average power over the entered duration.
01Formulas and symbols
Formulas used
E
P · tElectrical energy from power multiplied by operating time.C
E · cEstimated cost from energy multiplied by the tariff per kWh.02Assumptions and limits
Scope of validity
- Power and tariff are nonnegative; operating time is strictly positive. Power is treated as constant or as the average power over the entered duration.
03Validation example
Reference numerical case
- P = 2 kW, t = 3 h and c = 0.25 currency/kWh give E = 6 kWh and C = 1.50 currency units.
04References
Technical references
FAQ
Which currency should I use?
Any currency can be used. Enter the tariff in that currency per kWh; the numeric cost result is expressed in the same currency.
Does this include fixed charges or taxes?
No. The calculator multiplies energy by the entered variable tariff only. Add subscriptions, taxes, demand charges or tiered pricing separately.
05From power to energy and cost
Energy is power integrated over time; with constant or average power, E = Pt. The tariff is then applied with C = Ec after conversion to kWh.
06Limits and conventions
The calculator assumes one constant tariff and constant or average power. It does not model tiered tariffs, time-of-use pricing, reactive energy, demand charges or fixed fees.
07Common mistakes
Do not confuse kW, a unit of power, with kWh, a unit of energy. Check whether the tariff is quoted per kWh before entering it.