Separate extra billing days from changes in daily use, energy price, and other charges. No bill upload needed.
Compare two billing periods
Example inputs
Have your previous and current bills ready. Copy kWh, billing days, per-kWh prices and remaining charges. See result ↓
Previous period
kWh
days
¢/kWh
Add supply + delivery per kWh. $0.20/kWh = 20 here.
USD
Current period
kWh
days
¢/kWh
Add supply + delivery per kWh. $0.22/kWh = 22 here.
USD
Use combined per-kWh supply and delivery rates. Put remaining nonnegative charges in “other charges,” without counting them twice. Do not enter account numbers or upload bills.
Example result — enter figures from your two bills
Modeled bill increase
$51.40
Previous $130.00 → Current $181.40
Daily electricity use increased by 10%. Check the breakdown below to separate usage from extra billing days and price changes.
Previous daily energy20 kWh
Current daily energy22 kWh
More / fewer billing days
+$20.00
Change in daily energy use
+$14.00
Change in per-kWh rate
+$15.40
Change in other charges
+$2.00
These components add to the modeled change before rounding. Allocation applies days → daily use → rate → other charges, in that order. It does not identify which appliance or weather event caused a change.
A period with 600 kWh over 30 days averages 20 kWh/day. A period with 770 kWh over 35 days averages 22 kWh/day. Total energy increased 28.3%, but daily energy increased 10%. Looking only at the total hides the extra five billing days.
A transparent order of calculation
Starting with the previous bill, we apply new billing days at the old daily usage and rate, then new daily usage at the old rate, then the new rate, then other charges. Those four contributions sum to the modeled bill difference before rounding. Changing the order can redistribute interactions between components.
Check the model against your bill
Each modeled total equals kWh × variable price + other charges. If it does not match your actual bill, check excluded taxes, credits, adjustments, and complex tariff rules. Do not add a fixed fee on top of a rate calculated by dividing the entire bill by kWh. Negative credits and tiered or time-of-use tariffs need a more detailed review.
What this cannot diagnose
The components describe arithmetic, not the physical cause. Higher daily use might justify checking schedules or equipment, but this calculator cannot identify an appliance, verify a meter, or prove a weather effect. Contact your utility about disputed readings or unexplained charges.