Compare daily use, not just dollars
First compare kWh per day with the same month last year. If daily use is flat but dollars rose, the likely cause is a rate, fee or billing-period change.
Match the increase to a load
A 1,500-watt heater used eight hours a day adds about 360 kWh in 30 days. Use appliance math to see whether a suspected device is large enough to explain the change.
- Heating and cooling runtime
- Electric resistance heat
- Water heating
- EV charging
- Pool pumps and dehumidifiers
Check the meter and bill details
Look for an estimated meter read, a catch-up adjustment, a past-due balance or a plan change. Contact the utility if the meter reading on the bill does not match the meter or portal history.
Worked example: test whether a heater can explain the increase
A 1,500-watt heater is 1.5 kilowatts. At eight hours per day for 30 days, it uses 360 kWh. At an entered variable price of $0.18 per kWh, that scenario adds $64.80 before taxes or fixed charges.
If the bill increased by only 90 kWh, that eight-hour scenario cannot match the evidence. Recheck actual runtime, other loads and whether the comparison periods had the same number of days.
Investigate in this order: service days, kWh per day, effective variable price, fixed adjustments, weather-sensitive loads, then meter or equipment concerns.
Primary sources and scope
These links support the units or diagnostic method used above. They do not replace your provider’s current tariff, bill or safety instructions.
- EIA — Measuring electricity ↗ — Supports the watts-to-kWh relationship used in the example.
- EIA — Degree days ↗ — Explains heating and cooling degree days as weather-demand indicators.
This guide explains general billing math. Utility tariffs and local rules control your actual charges. Sources and update practices are documented in our methodology.
Read the methodology →