Bill Calculations and Plan Choices
How to calculate a natural gas bill in Canada: GJ, cubic metres and each charge
Calculate a Canadian natural gas bill step by step: GJ vs m³, basic charge, delivery, storage and transport, cost of gas, with FortisBC's posted rates and examples.
A natural gas bill is usage multiplied by several per-unit charges, plus a fixed daily or monthly charge, plus tax. In British Columbia and Alberta usage is billed in gigajoules (GJ), a unit of energy; in Ontario Enbridge bills in cubic metres (m³), a unit of volume. To calculate a bill, take the usage, multiply by each per-unit charge (delivery, transportation and storage, cost of gas or gas supply), add the fixed charge for the number of days, add any rate riders, and apply GST or HST. FortisBC's posted Mainland rates effective 1 July 2026 give a clean example: 8 GJ in a 31-day month comes to $113.88 before other fees and taxes.
This guide is part of comparing plans with worked examples. For what changed in 2025, see natural gas rates after the carbon charge was removed.
Units: GJ and m³
- GJ measures the energy content of the gas. One GJ is a billion joules.
- m³ measures volume at standard conditions. The energy in a cubic metre depends on the gas composition.
As a rough guide, one cubic metre of natural gas contains about 0.037 to 0.039 GJ, so 1 GJ is about 26 to 27 m³. Utilities that bill in m³ set their prices per m³ and adjust for heat content in their rate-making; utilities that bill in GJ convert the metered volume using a measured heat value, often shown on the bill. Use your bill's own figures when you have them.
| Usage | Approximate equivalent (illustrative 0.038 GJ/m³) |
|---|---|
| 100 m³ | 3.8 GJ |
| 250 m³ | 9.5 GJ |
| 10 GJ | about 263 m³ |
Worked example 1: FortisBC, Mainland and Vancouver Island
Posted residential rates effective 1 July 2026:
| Charge | Rate | 8 GJ, 31 days |
|---|---|---|
| Basic charge | $0.4216 per day | 31 × $0.4216 = $13.07 |
| Delivery | $8.469 per GJ | 8 × $8.469 = $67.75 |
| Storage and transport | $2.472 per GJ | 8 × $2.472 = $19.78 |
| Cost of gas | $1.660 per GJ | 8 × $1.660 = $13.28 |
| Total before other fees and taxes | $113.88 |
FortisBC notes that its commodity charges are reviewed by the BCUC every three months and delivery charges annually, so check the current table before using these numbers.
A winter month at 18 GJ, 31 days: $13.07 + 18 × ($8.469 + $2.472 + $1.660) = $13.07 + 18 × $12.601 = $13.07 + $226.82 = $239.89 before fees and GST. Per GJ, the bill is $13.33 in winter versus $14.24 in the 8 GJ month, because the basic charge is spread over more gas.
Worked example 2: an Ontario bill in m³ (placeholder prices)
Enbridge Gas bills have a customer charge (fixed monthly), delivery to you (¢/m³, often in blocks), transportation to Enbridge (¢/m³), gas supply charge (¢/m³), and cost adjustments. Rates differ by rate zone and change with quarterly QRAM decisions approved by the OEB. To show the method only, use placeholder values:
- customer charge: C per month;
- delivery: D ¢/m³;
- transportation: T ¢/m³;
- gas supply: G ¢/m³.
For 210 m³: bill before tax = C + 210 × (D + T + G) ÷ 100, then add 13% HST. Put in the actual rates for your zone from Enbridge's rates page.
Worked example 3: Alberta, Default Rate Tariff or retailer
Alberta gas bills show the gas energy charge (DRT or retailer price × GJ), an admin charge, and delivery (fixed daily plus variable per GJ) from your distributor, plus riders and possibly a municipal franchise fee. Because the DRT can change every month, a fixed-price retail gas contract trades monthly swings for certainty. To compare, multiply each option's ¢ or $/GJ by your annual GJ and add fees; delivery is the same either way. See fixed contracts vs the default rate.
Estimating annual gas use
| Home type (illustrative) | Main gas uses | Annual GJ, rough range |
|---|---|---|
| Apartment or condo with gas cooking only | Stove | 5–15 |
| Townhouse with gas water heater | Water heating, cooking | 25–45 |
| Detached house with gas furnace and water heater | Space and water heating | 70–140 |
Real figures depend on climate zone, insulation, thermostat settings and household size. Your 12-month history is the best guide; most utilities show it in your online account.
What changes the bill most
- Heating degree days. Gas furnaces scale with cold. A January can use three to five times the GJ of a September.
- Fixed charges in summer. In low-use months the basic charge can be most of the bill.
- Commodity resets. Quarterly or monthly changes in cost of gas.
- Riders. Temporary charges or credits settling past forecasts.
If gas heating costs are your main concern, the choice of heating equipment is a separate question beyond this site's scope; here we focus on reading and comparing the rates you pay.
Equal payment plans
Gas bills are the most seasonal of household bills, which is why most gas utilities offer an equal or budget payment plan. It does not change the price, only the timing; see equal billing and budget plans.
FAQ
Why is my summer gas bill not close to zero?
The daily basic or customer charge applies every day the account is open, even with minimal use.
Can I convert my Ontario m³ to GJ to compare with BC?
Roughly, using about 0.038 GJ per m³, but cross-province comparisons have limited use because you cannot choose another province's utility.
Is cost of gas the only part a marketer replaces?
Mostly. Delivery and the basic charge stay with the utility.
Do I pay GST on gas?
Yes, GST or HST applies to residential natural gas bills; provincial rules vary for the provincial portion.
Sources
- FortisBC — residential rates effective 1 July 2026 and sample bill
- Enbridge Gas — rate components and QRAM updates
- Ontario Energy Board — natural gas rate approvals
- Utilities Consumer Advocate — Alberta Default Rate Tariff table
- British Columbia Utilities Commission — gas rate decisions
