Bill comparison
Why did my electric bill go up?
Enter an earlier bill and a later one. We split the difference into what changed in usage, in the price per kWh, and in fixed charges and credits. The parts add up exactly to the change.
Updated November 1, 2026 · Edited by Carlos Gil, publisher
Short answer
- Compare the electric charges, kWh and billing days on two bills. The change splits into usage (more or fewer kWh at the old price), price (a different price per kWh) and fixed charges, fees and credits.
- The parts add up exactly to the difference, and kWh per day shows whether a longer bill, rather than heavier use, explains it.
Check the rate name on the bill. If unsure, leave “Not sure”.
What changed
Illustrative exampleThe later bill is +$41.00 compared with the earlier one. Most of the change came from using a different amount of electricity.
- Earlier bill
- $150.00
- Usage
- +$24.00
- +200 kWh at the earlier price of 12.00¢/kWh. Of that, $0.00 came from billing days (no change) and +$24.00 from using more per day.
- Price per kWh
- +$12.00
- 12.00¢/kWh → 13.00¢/kWh on 1,200 kWh.
- Fixed charges, fees and credits
- +$5.00
- $30.00 → $35.00.
- Later bill
- $191.00
| Earlier | Later | |
|---|---|---|
| kWh per day | 33.3 | 40.0 |
| Cost per day | $5.00 | $6.37 |
| Billing days | 30 | 30 |
What this can't tell you
How the split works
We model each bill as kWh × price per kWh + other charges. With the per-kWh lines, the price is those lines ÷ kWh and "other" is everything else (fixed charges, most taxes, credits). Without them, the price is the all-in average and "other" is zero.
- Usage = change in kWh × earlier price.
- Price = later kWh × change in price.
- Other = change in other charges.
These three add up exactly to the change in the bill. The usage part is split once more into billing days and kWh per day, and those two add up to the usage part, so nothing is counted twice. Attribution conventions are a choice: valuing the usage change at the later price instead would move some dollars between "usage" and "price" without changing the total.
With the example: 200 more kWh × 12¢ = $24.00; 1,200 kWh × 1¢ higher = $12.00; other charges $30.00 → $35.00 = $5.00. $24.00 + $12.00 + $5.00 = $41.00, the difference between $150.00 and $191.00. More detail in our methodology.
Illustrative example: four more days and a fuel change on a JEA bill
Illustrative example (invented usage, real JEA rates)
Two JEA bills priced on JEA's rates effective October 1, 2026, the earlier one at October's fuel rate and the later one at November's, before taxes and fees. Each bill uses a single month's fuel rate; JEA's rates page doesn't say how a fuel change is applied when a billing period spans two months.
| Line | Earlier bill | Later bill |
|---|---|---|
| Billing days | 29 | 33 |
| kWh used | 1,000 | 1,150 |
| kWh per day | 34.5 | 34.8 |
| Basic monthly charge | $21.00 | $21.00 |
| Energy charge | $78.15 | $92.71 |
| Fuel charge | $43.26 | $57.21 |
| Charges before taxes and fees | $142.41 | $170.92 |
The later bill is +$28.51. The split:
- Usage +$18.21: 150 more kWh at the earlier per-kWh price of 12.14¢/kWh. Of that, +$16.75 comes from the 4 extra billing days and only +$1.47 from using more per day.
- Price +$10.30: the per-kWh price rose from 12.14¢/kWh to 13.04¢/kWh. Two things are inside it: November's higher fuel rate on all 1,150 kWh (+$7.46) and the 150 kWh above 1,000 priced at JEA's higher energy tier (+$2.83).
- Fixed charges $0.00: the basic monthly charge was the same on both bills.
Read together: daily use barely moved, so this household didn't change much. Most of the increase came from a longer bill and a higher fuel rate, neither of which a change at home would undo. That's a different conclusion from the one the totals alone suggest.
Illustrative example: the same FPL rate, a higher price per kWh
Illustrative example (invented usage, real FPL rate)
Both bills are priced on FPL's October 2026 residential rate, before taxes and local fees: 950 kWh over 30 days ($126.97), then 1,400 kWh over 31 days ($190.13).
- Usage +$55.16: 450 more kWh at the earlier bill's 12.26¢/kWh. One extra billing day accounts for +$3.88; the rest is higher daily use.
- Price +$8.00: FPL's rate didn't change, but the later bill has 400 kWh above 1,000, each priced 2.00¢ higher. The average per-kWh price rose from 12.26¢/kWh to 12.83¢/kWh.
- Fixed charges $0.00: the $10.52 base charge is on both bills.
Daily use went from 31.7 to 45.2 kWh, a rise of 13.5 kWh a day. For scale, that's what a 1,500 W appliance drawing full power for 9.0 hours a day would use; the appliance calculator tests whether a suspect fits.
On a tiered rate, a price change in the split doesn't always mean the utility changed its prices. Check the rate sheet first; if it's the same, the price part is your usage crossing the 1,000 kWh line, and the usage part is where to look.
How to read each part of the split
- Billing days. More days means more kWh even at the same daily use. Nothing to fix; the next bill may be shorter. Judge your household by kWh per day instead.
- Daily use. This is the part your household controls. If it rose, look at what changed: the season, people at home, guests, new equipment, or something running longer. The appliance, space heater and pool pump calculators put numbers on specific suspects.
- Price per kWh. Rate changes, fuel adjustments and, on tiered rates, more of your usage landing above the threshold. Check the per-kWh lines on both bills against the utility's rate sheet, and see the FPL and JEA pages for current prices.
- Fixed charges, fees and credits. A new fee, a changed tax or a credit that appeared on one bill and not the other. Compare the fixed lines one by one.
- Several parts at once. Real changes usually mix more than one part. Start with the largest, because that's where an explanation, or a change at home, makes the most difference.
When the split is approximate, and what makes it exact
The split assumes one price per kWh on each bill. The total always adds up, but on these bills one part can carry effects that belong to another. The U.S. Department of Energy describes time-of-use rates as prices that change by set amounts at set times, and demand charges as charges based on your maximum demand in kW during a period, typically each month.
| Bill type | What the split can't separate | What makes it exact |
|---|---|---|
| Tiered (FPL and JEA above 1,000 kWh) | A rate change from more usage landing in the higher tier | The kWh in each tier and the tier prices, as in the JEA example above |
| Time-of-use | A price change from a shift in when you used power | On-peak and off-peak kWh from each bill |
| Demand charge | A higher peak draw from more kWh | The kW demand line on each bill |
| Solar net metering | More solar exported from less use at home | Delivered and exported kWh, not only the net figure |
| Combined utility bill | Water, sewer or gas changes from electricity changes | The electric section's charges only |
Before you compare: a short checklist
- Use two bills for the same home and the same electric service.
- Take this period's electric charges from each, not the amount due, and leave out water, sewer, gas and past balances.
- Copy kWh and billing days from each bill; count the days between service dates if they aren't printed.
- If you can, add the charges priced per kWh for both bills, so price and fixed charges separate cleanly.
- For a question about weather, compare with the same month a year earlier rather than last month. JEA's bill shows 13 months of usage, and FPL's Energy Manager shows when, where and how your home uses energy.
- Note any one-time credit, fee or adjustment on either bill. It lands in the fixed-charges part, and knowing it's there stops you reading it as a lasting change.
- Pick the rate type that matches your bill so the tool can say which parts of the split are approximate.
Frequently asked questions
Why did my electric bill go up when I didn't use more electricity?
If kWh per day stayed about the same, the extra cost came from somewhere else: more billing days, a higher price per kWh such as a fuel charge change, higher fixed charges or fees, or amounts that aren't this period's electricity, like a past balance.
How do billing days change a bill?
A bill that covers more days includes more days of use, so its kWh and cost rise even if daily use doesn't. Dividing kWh by billing days puts two bills on the same footing.
Can a fuel charge change my bill?
Yes, even when your usage doesn't change. JEA, for example, set its fuel rate at $43.26 per 1,000 kWh in October 2026 and $49.75 in November, a $6.49 difference on 1,000 kWh.
What if my utility uses tiered or time-of-use rates?
The comparison still adds up. With tiered rates the price part also reflects how much usage fell into the higher tier, and with time-of-use rates it can't separate a price change from a shift in when you used power. The tool flags both.
Why does the tool ask for the charges priced per kWh?
With those lines from both bills it can separate the price per kWh from fixed charges and fees. Without them it uses each bill's all-in average, so the price part also includes any change in fixed charges.
Sources
- U.S. Department of Energy (FEMP), Evaluating your utility rate options · checked October 31, 2026
- JEA rates, including Electric Rates Definitions · checked October 31, 2026
- FPL residential rates, October 2026 (PDF) · checked October 31, 2026
- FPL Energy Manager · checked October 31, 2026