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Every charge rebuilt and traced to the filed tariff.

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SampleA real ComEd home bill with the numbers changed, not yours. Sixteen charge lines in three sections, each of which has to add up to its own printed subtotal before anything else is claimed.

Sample · ComEd · Residential · May 1 to Jun 2, 2026

This bill checks out.

We read all 16 charges and added them up again. They come to $281.06, the same total ComEd printed. Every rate we could check against a public filing matched.

What this bill costs per kWh

18.52¢

per kWh, everything included

$281.06 ÷ 1,518 kWh

The price to compare

10.40¢

per kWh for supply

ComEd's price to compare for June 2026, posted by the Illinois Commerce Commission. It leaves out the purchased electricity adjustment.

Where the $281.06 went

Supply$161.35the electricity itself
Delivery$117.44wires, meter, ComEd
Taxes and fees$22.67state, city, programs
Credits−$20.40taken off the total

Two things this bill shows

A battery won't cut this bill's delivery charge

This rate has no demand charge. A battery sold on demand savings saves nothing here.

Summer runs 2.3× the quietest month

Jun '25May 1,259Jun 1,518

See all 16 charges, line by lineEach rate, how we checked it, and the filing it matches

Rate printed on the bill: Residential - Single.

16 lines read, 11 recompute to the cent from their own printed rate, 4 checked against filed records (ComEd filed ratebook, ICC posted price to compare).

All 16 charge lines, read, and they add up to $281.06

ChargeQuantityRateAmountFiled
Supply
Electricity Supply ChargePrice to compare1,518 kWh$0.08677$131.72$0.10399 with transmission ICC posting
Transmission Services ChargePrice to compare1,518 kWh$0.01722$26.14$0.10399 with supply ICC posting
Purchased Electricity Adjustment$3.49
Delivery
Customer ChargeDoes not move$15.50$15.39 of $15.50 filed ratebook
Standard Metering ChargeDoes not move$3.87$3.87 filed ratebook
Distribution Facility Charge1,518 kWh$0.06333$96.13$0.06333 filed ratebook
IL Electricity Distribution Charge1,518 kWh$0.00128$1.94$0.00128 filed ratebook
Taxes, fees and credits
Environmental Cost Recovery Adj1,518 kWh$0.00009$0.14
Renewable Portfolio Standard1,518 kWh$0.00516$7.83
Coal to Solar and Energy Storage Fund1,518 kWh$0.00009$0.14
Zero Emission Standard1,518 kWh$0.00087$1.32
Carbon-Free Energy Resource Adj1,518 kWh−$0.01344−$20.40
Energy Efficiency Programs1,518 kWh$0.00369$5.60
Energy Transition Assistance1,518 kWh$0.00084$1.28
Low Income Discount Recovery$1.35
State Tax$5.01
Total$281.06

Every rate here is filed with the Illinois Commerce Commission and is the same for everyone on this rate. Every line on a ComEd bill, explained.

Every line on your bill was extracted and re-added. The computed total matches the Service Period Total ComEd printed, which is how you know nothing was missed or misread.

How, and the source
How
sum of 16 line items = $281.06 = printed total
Source
Your bill, charge details section

You are on ComEd's Single Family Without Electric Space Heat delivery class

We did not take this from the label on your bill, which does not say whether the home has electric space heat. We rebuilt the Distribution Facilities rate for all four residential delivery classes we hold and found the one whose rate matches the rate printed on your bill. We do not hold ComEd's rules for which class a customer belongs in, so this is the class you are billed on, not a check that it is the right one.

How, and the source
How
printed $0.06333/kWh matches Single Family Without Electric Space Heat in the June 2026 billing period
Source
ComEd filed ratebook, matched to your bill

Price to compare: 10.399 c/kWh; you paid 10.629 c/kWh

ComEd printed a price to compare of 10.399 cents per kWh. Your supply and transmission rates add to 10.399 cents, which is the same number -- consistent with being on ComEd's default supply rather than a retail supplier. What you actually paid for supply was 10.629 cents per kWh, because the price to compare excludes the purchased electricity adjustment and your bill includes it.

How, and the source
How
supply $0.08677 + transmission $0.01722 = 10.399 c/kWh vs printed 10.399 c/kWh
Source
Your bill, supply section and the price-to-compare notice

You have no demand charge, so peak shaving saves you nothing on delivery

Your delivery charges are billed entirely on how much energy you use, not on how fast you use it. Cutting a short spike in your usage would not reduce this bill by a cent. Anyone selling you a residential battery on demand-charge savings in ComEd territory is selling a saving that does not exist on this rate.

How, and the source
How
Distribution Facilities Charge billed per kWh, not per kW
Source
Your bill, delivery section

Supply $161.35 / Delivery $117.44 / Taxes, fees and credits $2.27

What you paid to buy the electricity, what you paid to have it delivered, and what you paid in taxes, fees and credits. Each section was re-added against its own printed subtotal.

How, and the source
How
Supply: lines sum to $161.35 vs printed $161.35; Delivery: lines sum to $117.44 vs printed $117.44; Taxes, fees and credits: lines sum to $2.27 vs printed $2.27
Source
Your bill, charge details section

The ICC posted 10.399 c/kWh for June 2026, the price your bill printed

The Illinois Commerce Commission posts ComEd's residential price to compare every month, and for June 2026 it posted 10.399 cents per kWh, the same figure your bill printed. That is a check against a source other than the bill itself. Your bill covers May 1, 2026 to June 2, 2026. ComEd's posted price rose from 9.660 (May 2026) to 10.399 (June 2026), and your supply lines were billed at the later figure for the whole period. On your 1,518 kWh the difference between the two postings is $11.22. A year earlier, June 2025's posting was 10.028, so this price is 0.371 cents higher than the same month last year. The ICC also posted the purchased electricity adjustment for June 2026 at 0.230 cents per kWh; the adjustment on your bill works out to 0.230 cents per kWh on the same 1,518 kWh, which agrees.

How, and the source
How
printed 10.399 c/kWh = ICC posting for 2026-06; (10.399 - 9.660) c/kWh x 1,518 kWh = $11.22; PEA $3.49 / 1,518 kWh = 0.230 c/kWh vs posted 0.230
Source
Illinois Commerce Commission, Historical Prices to Compare for ComEd, retrieved 2026-08-31; residential non-space-heat class

13 months of usage, from 1,259 to 2,894 kWh a month

Your highest month was August at 2,894 kWh; your lowest was May at 1,259 kWh. That is a 2.3x swing across the year.

How, and the source
How
max 2,894 / min 1,259 = 2.30x
Source
Your bill, the usage graph

Know which lines on your bill can move and the levers that move them.

Read mineIt takes about ten seconds.

Independent · No commission

This one needs no bill.

A spec sheet gives you watts. A bill gives you kilowatt-hours. They are not the same kind of number: one is a rate, the other is a quantity, and getting between them takes a duration. Convert either direction here. The reader above is for the bill itself; nothing from it is needed for this.

Both directions need a duration, because a rate and a quantity are only related through time.

The nameplate or measured draw, off the label or the spec sheet.

1 kW is 1,000 W. Appliance labels usually say watts, equipment and solar arrays usually say kilowatts.

In hours. A full day is 24, a 30 day billing period is 720. For minutes, divide by 60.

Phantom Grid reconstructs the shape your bill already reflects. It does not recommend, project savings, or sell anything.

Electricity Bills

kWh Calculator: Convert Watts and Kilowatts to Kilowatt-Hours

Free kWh calculator. Convert watts or kilowatts to kilowatt-hours over any duration, or convert kWh back to average kilowatts. Pure unit conversion, no rates and no dollars, in your browser.

UPDATED AUG 10 2026

Most people land here holding two numbers that will not talk to each other. A spec sheet or an appliance label gives watts. An electricity bill gives kilowatt-hours. They are not the same kind of measurement, and no amount of staring converts one into the other.

A kilowatt is a rate: how fast something draws power right now. A kilowatt-hour is a quantity: that rate multiplied by how long it ran. The missing piece between them is always time, which is why the converter above asks for a duration in both directions and cannot work without one.

No rates, no dollars, nothing uploaded. This page converts units and stops.

The two formulas

Watts or kilowatts to kilowatt-hours:

kWh = kW x hours
kWh = (watts / 1,000) x hours

Kilowatt-hours back to average kilowatts:

average kW = kWh / hours

That is the entire arithmetic. The only thing to be careful about is the 1,000: a kilowatt is 1,000 watts, so a wattage off a label has to be divided by 1,000 before it is multiplied by hours.

Worked example, watts to kWh

A 1,500 W space heater runs for 3 hours.

  1. Convert to kilowatts: 1,500 / 1,000 = 1.5 kW
  2. Multiply by the hours: 1.5 x 3 = 4.5 kWh

The heater draws at a rate of 1.5 kilowatts the whole time it is on. It accumulated 4.5 kilowatt-hours. Left running 3 hours a day for 30 days, the same heater accumulates 135 kWh.

Worked example, kWh to average kW

A bill says 900 kWh over a 30 day period. A 30 day period is 30 x 24 = 720 hours.

900 / 720 = 1.25 kW average

The building averaged 1.25 kilowatts across the whole month. Note the word average, because it is doing real work in that sentence. The month almost certainly did not run flat at 1.25 kW. It had a floor overnight and peaks during the day, and a monthly total cannot tell you where they fell. Only interval meter data can.

Common questions

What is the difference between kW and kWh? kW measures power, the rate of draw at an instant, the way miles per hour measures speed. kWh measures energy, the accumulated amount, the way miles measures distance covered. A short, violent draw can be a large kW and a small kWh. A modest draw held all month can be a small kW and an enormous kWh. The full distinction, and why your bill charges them on separate lines by different logic, is in What is peak demand?.

How many watts are in a kWh? This question has no answer as asked, and that is the point. Watts are a rate and kilowatt-hours are a quantity, so there is no fixed conversion between them without a duration. 1,000 watts held for one hour is 1 kWh. 100 watts held for ten hours is also 1 kWh.

How do I convert kWh to watts? Divide the kilowatt-hours by the hours to get average kilowatts, then multiply by 1,000 for watts. 900 kWh over 720 hours is 1.25 kW, which is 1,250 W on average.

How many kWh does a 100 W bulb use? 100 W is 0.1 kW. Run for 5 hours it uses 0.5 kWh. Run for a 720 hour month it uses 72 kWh.

Is the kW on my bill the same as the average kW this calculator returns? No, and confusing the two is expensive on a commercial bill. The kW line on a bill is usually peak demand: the single highest interval in the period, not the average across it. The average will always be lower, often several times lower.

Does the calculator convert MWh or Wh? Not directly, but the steps are the same. 1 MWh is 1,000 kWh. 1 kWh is 1,000 Wh.

What this page does not do

It does not price anything. Converting units and pricing electricity are separate questions, and mixing them is how most calculators end up answering neither well. If you want the cost side, three other pages handle it properly: what a kilowatt-hour actually cost you last month, all in, is the one to start with.