Formula
The difference of the dials is scaled by the meter's multiplier:
kWh = (ending reading − starting reading) × multiplier
A multiplier of 1 means the dial is already in kilowatt-hours. This page does not know the watts of any appliance.
Assumptions
- Both readings are from the same meter.
- The multiplier is the one printed on that meter.
- The ending reading is later than the starting reading.
Worked example
A meter moving from 42,150 to 42,890 with a multiplier of 1 used 740 kWh.
Input definitions
- Reading
- The cumulative kilowatt-hour number on the meter face.
- Multiplier
- A factor some meters print when one dial step is more than one kilowatt-hour.
Limitations
This is a planning estimate. The rate, sun hours, and losses are numbers you type. It is not a utility bill, a solar design, or a room-by-room load calculation.
Questions
What if the meter reset?
This page cannot cross a rollover. Enter readings from one continuous climb.
Does this include the price?
No. The kilowatt-hour cost page multiplies a total you already have by the rate on your bill.