A power bill is actually three invoices stapled together: what you consumed, what it cost to deliver it, and what regulators added on. Utilities don’t design the statement to make that obvious — here’s the map.

Line 1: The usage — kWh

The one number that matters most: kWh used this billing cycle (sometimes shown as current read minus previous read, occasionally as “estimated” if nobody read the meter). This is the odometer. Every appliance calculation on this site lands in this unit — 880 kWh means 880 one-thousand-watt-hours of cumulative draw, however it happened.

Sanity-check it: US homes average roughly 850–900 kWh/mo. Half that in a mild month is normal; double it in August is normal too — the biggest-loads ranking explains why.

Line 2: The rate — and why it’s not one number

What each kWh costs depends on your plan structure:

• Flat rate — one ¢/kWh all day, all month. Simplest and still most common.
• Tiered — first ~500 kWh at one rate, the rest more expensive. Conservation nudge; the AC-heavy month crosses tiers fast.
• Time-of-use (TOU) — price varies by hour: peak afternoons can be 2–3× off-peak nights. Your meter logs when kWh happened, not just how much.
• Demand — rare for homes, standard for businesses: a charge on your peak kW (worst 15–30 minute burst), not just total kWh. If your bill has a demand line, simultaneous big loads (dryer + oven + EV) cost extra even at low monthly totals.

Line 3: Supply vs delivery

The quiet split on most bills:

• Supply / generation / energy charge — the electricity itself: power plants, fuel, or your chosen retail supplier’s contract. This is the part “rate shopping” (in deregulated states) actually compares.
• Delivery / distribution / wires charge — poles, transformers, meters, crews: the regulated monopoly part nobody can shop. Often 40–50% of the bill, sometimes priced per-kWh, sometimes partly fixed.

An “11¢/kWh plan” advertised by a supplier means supply only — delivery rides on top, which is why the effective rate math below exists.

Line 4: The stack of small print

• Customer/service charge — fixed monthly fee for being connected, ~$5–25.
• Riders & adjustments — fuel-cost true-ups, storm recovery, efficiency-program fees, renewable mandates. They drift semi-annually and explain “my rate went up but they said it wouldn’t.”
• Taxes & franchise fees — state/local cut, usually a small %.

The honest math: your effective rate

Utilities print component rates; they rarely print the only one that lets you compare anything:

effective rate = total amount due ÷ total kWh

Example: $128.77 due ÷ 890 kWh = $0.145/kWh — even if the supply line advertises $0.11. This is the number to enter in the estimator, the number to compare between suppliers, and the number that makes “my rate is 11 cents” honest. Note it moves month to month: the fixed customer charge dilutes over more kWh, so effective rate falls as usage rises on flat plans.

A dissection, line by line

A typical flat-rate statement, translated:

line on the bill	what it actually is	moves with usage?
Customer charge $9.60	being connected at all	no
890 kWh × $0.0941	supply/energy	yes
890 kWh × $0.0312	delivery/wires	yes
Storm-recovery rider $4.10	regulator-approved add-on	semi-fixed
State & local tax $3.55	government cut	% of subtotal
Total $128.77	the three invoices summed	—

Same exercise works on any bill: the per-kWh lines divided by usage give your marginal rate; everything else is your fixed overhead of being a customer.

Reading the seasonal story

Pull last year’s bill for the same month before diagnosing anything. July-vs-July tells you whether the AC is eating more than it used to; July-vs-May just tells you it’s July. A steadily climbing kWh baseline in the mild months — when HVAC barely runs — is the signature of a new always-on load: a second fridge, a pool pump left on a longer schedule, a PC that stopped sleeping (see phantom loads).

Edge cases worth knowing

• “Estimated” reads — if the meter wasn’t read, the utility guessed; a later “actual” read can show a catch-up spike that looks like a usage explosion but is really bookkeeping. The read type is printed on the statement.
• Budget billing — an optional plan that charges the yearly average each month instead of the real monthly figure. Bills stop swinging, but the statement’s kWh is still the truth — the dollar total is just smoothed.
• Solar/net-metered bills — a different animal entirely: usage, generation and net-flow lines, often with a true-up. The supply-vs-delivery logic still applies underneath.

Three moves worth making

1. Record your effective rate once — it calibrates every estimate you do here.
2. Check the meter-read type — “estimated” reads drift; a catch-up month isn’t a usage spike.
3. Ask about TOU only with your usage history in hand — utilities publish your hourly data in the account portal; shifting works when your big loads can move, not before.

Once the statement reads as consumption × rate + delivery + fees, it stops being a surprise and starts being a receipt you can audit — and every row on the estimator maps to a real slice of it.

Frequently asked questions

What's the difference between kW and kWh on my bill?

kWh is energy — what you consumed all month. kW is demand — your peak rate of use at a single moment (usually the worst 15–30 minute interval). Most homes pay only per-kWh; demand charges appear on commercial bills and some newer residential plans, where running the dryer + oven + EV charger simultaneously gets penalized.

Why does my bill show a different ¢/kWh than the advertised rate?

Because the advertised rate is usually just the supply/energy portion. Delivery charges, transmission, riders, taxes and the fixed monthly customer charge stack on top. Divide your total by your kWh and you'll get your real effective rate — typically $0.13–0.25 in the US even where the 'rate' advertises $0.11.

What is a 'customer charge' or 'service fee'?

A fixed monthly amount ($5–25 typically) you pay just to be connected — it doesn't change with usage. It's why your bill never reaches $0 in a month you barely use power, and why effective ¢/kWh always looks higher at low usage.

What are 'riders' and 'adjustments'?

Add-ons regulators approve outside the base rate: fuel-cost adjustments, storm-recovery charges, energy-efficiency program fees, renewable mandates. They change semi-regularly and explain why your ¢/kWh drifted even when 'rates didn't go up.'

Should I switch to a time-of-use plan?

Only if you can genuinely shift load — EV charging overnight, laundry/dishwasher off-peak, AC pre-cooling. On TOU the same kWh can cost 3× more at 5 p.m. than at 2 a.m. Check your utility's usage history first: households home all day with afternoon AC sometimes pay more on TOU.

My bill doubled but I didn't change anything — why?

Almost always weather (a heat wave or cold snap multiplies the dominant HVAC load), a rate-case increase that arrived quietly, a 'estimated' previous meter read catching up, or a new large load (EV, pool, space heater habit). Compare kWh — not dollars — against the same month last year before assuming something broke.