The short answer
A US natural-gas bill has two structural pools: supply (the gas itself, billed as therms × per-therm rate) and delivery (the pipeline + meter + regulated charges). In deregulated states (OH, PA, MD, NY, IL, MA, NJ, CT, RI), only the supply line is shoppable. The delivery line stays with your local utility regardless of supplier choice.
A US residential natural-gas bill is structurally similar to an electricity bill — a supply line you can shop in deregulated states plus a delivery line that stays regulated — but the unit math is unfamiliar to most customers. Gas usage is metered in CCF (hundred cubic feet, the volume that flowed through your meter) and converted to therms (the heat content). Once you understand the CCF-to-therms conversion and the supply-vs-delivery split, every other line becomes readable. This guide decodes a typical bill line by line and shows which lines you can shop in your state.
Therms, CCF, BTU, MCF — the unit conversion table
Natural gas bills mix four related units: CCF (volume metered, hundred cubic feet), therms (heat content, 100,000 BTU each), BTU (the underlying energy unit), and MCF (thousand cubic feet, used for commercial accounts). Conversions are simple and most US bills do them automatically.
1 CCF of natural gas typically contains about 1.03 therms (the exact figure varies with the chemical composition; the utility measures it monthly and applies a "BTU factor" to your bill). 1 therm equals 100,000 BTU. 1 MCF equals 10 CCF and roughly 10.3 therms. On a residential bill you usually see CCF metered and therms billed.
The reason therms exist is that the utility wants to bill you for heat delivered, not volume. If the gas in your pipeline is slightly denser this month than last, you get more BTU per cubic foot, and the bill should reflect that. Therm-based pricing keeps the bill apples-to-apples across months.
The supply line vs the delivery line — what you can shop
In a deregulated gas state (Ohio, Pennsylvania, Maryland, New York, Illinois, parts of New Jersey, Massachusetts, Connecticut, Rhode Island), the bill splits into two pools. Supply is therms × per-therm supply rate plus a small monthly customer charge from your supplier. Delivery is everything else: distribution charges, customer charge, state riders, sales tax.
Supply is competitive — multiple licensed gas suppliers compete for your account. Delivery is set by the state PUC under utility tariff and is identical for every customer in the same delivery zone. Switching your supplier moves only the supply line.
On a typical 78-therm winter bill at $0.95/therm supply rate, supply runs about $74. Delivery + customer charge + riders + tax adds another $40-$50, bringing a winter bill to $115-$130. Summer bills (5-15 therms) run much smaller — supply is closer to $5-$15, with the customer charge dominating.
Infographic
The same supply-vs-delivery split that exists on the electricity bill
Walking every line on a typical residential gas bill
The supply line ("Gas Supply Cost", "Generation Charge", or "Cost of Gas" depending on the utility) is your therms used multiplied by the per-therm rate. This is the largest line in winter and the only line that changes when you switch suppliers in a deregulated state. In regulated states, the utility itself sets the supply rate through a regular fuel-cost adjustment process and you cannot shop it.
The customer charge ("Service Charge", "Customer Charge", or "Meter Charge") is a fixed monthly fee — typically $10 to $20 — that covers the cost of having your account on the utility books regardless of how much gas you use. On a low-usage summer bill, the customer charge can be 50 percent or more of the total.
Distribution charges cover moving gas from the regional pipeline to your meter; they scale with usage at typically $0.20 to $0.40 per therm. Riders and state programs are mandated pass-throughs (universal service fund, energy efficiency, infrastructure modernization) at 2 to 5 percent of the bill total. Sales tax is the final line at 4 to 7 percent depending on state.
Comparison table
Sample 78-therm bill broken down by line
| Line | Calculation | Amount |
|---|---|---|
| Gas supply (78 therms times $1) | 78 therms times $1.00/therm | $78.00 |
| Distribution | 78 therms times $0.27/therm | $21.06 |
| Customer charge | Fixed monthly | $11.50 |
| Riders + state programs | ~3 percent of subtotal | $4.60 |
| Sales tax | ~6 percent of subtotal | $6.80 |
| Total bill | $121.96 |
Shopping the supply line in a deregulated state
In Ohio, Pennsylvania, New York, Maryland, Illinois, Indiana, Georgia, parts of Massachusetts, New Jersey, Connecticut, and Rhode Island, residential gas customers can choose their supply rate from a competitive marketplace of licensed suppliers. Switching takes 5 to 10 minutes online, requires no service interruption, and the same utility continues to deliver gas through the same meter regardless of which supplier you pick.
The decision is mechanical: shop the per-therm rate against your utility default rate, lock a fixed-term contract (12 to 24 months is the sweet spot) when supplier offers run materially below the default, and re-shop when the contract ends. Default-service rates reset on a regular schedule (semi-annually in most states), and that reset is the single biggest cause of unexpected winter bill spikes for default-service customers.
The how-to-use-puco-apples-to-apples (Ohio), how-to-use-papowerswitch (Pennsylvania), and switching-natural-gas-supplier-step-by-step (general) guides walk through the actual shopping mechanics. Always verify the supplier license through your state PUC before signing — the supplier-license-how-to-verify guide covers the verification process.
For households with both electricity and gas in a deregulated state, the same supplier shopping logic applies to both bills independently. Most active suppliers (Constellation, Direct Energy, Inspire, Ambit, IGS) offer dual-fuel discounts when you sign both. Always compare the dual-fuel rate to the best single-fuel option for each — bundle discounts only matter if both rates are competitive on their own.
Infographic
Gas supplier switch sequence — same utility, new supply rate
Cross-checking the bill against the meter
Every gas bill should match the actual meter reading at your home. Utilities are required by every state PUC to read the physical meter on a regular schedule (typically monthly), but in practice some bills are based on estimates when the meter cannot be read on time, the route is delayed, or the meter is in a hard-to-access location.
The fastest defensive habit is a monthly self-read. Take a phone photo of your gas meter face on or near the day your bill is generated. The how-to-read-your-natural-gas-meter guide walks the dial-reading mechanic. If your bill shows an estimated read (usually marked with an "E" next to the read date) and your photo shows a different number, you have evidence to dispute. State PUCs require utilities to honour customer requests for an actual re-read within 5 business days in most states.
A self-read also lets you spot rate errors. If you signed with a new supplier and the bill still shows the utility default rate at the next billing cycle, the supplier enrollment may have failed at the EDI handshake. Call the supplier to confirm enrollment status. Most enrollment failures are administrative (typo on the address, mismatch on the account number) and resolve within one billing cycle once flagged.
- Photograph the meter monthly with your phone — the date stamp creates a record.
- Mark estimated reads ("E") on bills and dispute if the number looks off.
- After switching suppliers, verify the next bill shows the new supply rate.
- For low-usage summer bills, the customer charge dominates — that is normal.
Recap
Bottom line
A US natural gas bill becomes much easier to read once you know it has the same two-pool structure as the electricity bill: a supply line you can shop in deregulated states, plus a delivery line that stays with the utility regardless of supplier choice. Therms versus CCF is just unit math; the real decision is whether the supply rate on this bill is materially higher than the best fixed-rate offer available in your state today.
Run the diagnostic in three steps every winter. First, pull the bill and identify the per-therm supply rate. Second, compare to the best supplier offer on your state shopping portal (PA Power Switch, PUCO Apples-to-Apples, NY ESCO directory). Third, lock the better rate. Combined with monthly self-reads to catch estimated-read errors, this is the full hygiene pass that protects most US households from the largest avoidable gas-bill mistakes.
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