Why your utility bill changed
A higher payment does not necessarily mean higher usage. Separate current-period consumption, rates and adjustments before drawing conclusions. Compare periods with similar day counts when investigating behavior.
Separate quantity and price
In the Utility Bill Detective, enter both bills’ current-period charges, usage and flat rates in the same units. Usage effect = (new usage − old usage) × old rate. Rate effect = new usage × (new rate − old rate). Their sum exactly matches the change in modeled consumption charges.
Interpret the residual
For example, if usage rises from 200 to 250 kWh and the rate rises from USD 0.20 to USD 0.24/kWh, the usage effect is USD 10 and the rate effect is USD 10. If actual bills rise by 25, the remaining 5 is an unexplained residual, not proof of a provider error.
Check the statement lines
The residual can include fixed fees, tax, tier effects, credits or rounding. This decomposition is a comparison model for flat rates; use bill details to investigate the residual rather than treating it as a diagnosis.
Period usage is different from daily use
A 280 kWh bill over 35 days and a 224 kWh bill over 28 days both average 8 kWh/day. The Detective reports the period quantity effect correctly but does not normalize days or weather. Record the daily averages before attributing a higher total to a changed routine.
Worked example: Explain a bill with higher use and a higher rate
Related reading: Estimated meter readings and catch-up bills
Reference: EIA: electricity prices and time-based pricing.