How much does it cost to run a generator for 24 hours?

On natural gas, far less than most people expect. A 22 kW Generac Guardian burns 6.46 cubic metres an hour at half load per its spec sheet, so a 24-hour outage uses about 155 cubic metres. At Enbridge's Rate 1 marginal rate of roughly 28 to 30 cents a cubic metre that is $43 to $46 of gas before HST. The same machine on propane burns 9.57 litres an hour, which at $0.70 to $0.95 a litre comes to $161 to $218 for the same day.

Why is propane so much more expensive to run than natural gas?

Because you are buying energy at retail in a truck instead of through a pipe. On the same 22 kW machine over the same 24 hours at half load, natural gas costs about $43 at the low end and propane about $161, roughly four times as much. That gap is the strongest argument for running a gas line to the generator wherever an Enbridge main is available, and it compounds: a house that sees three multi-day outages a year is paying that difference every time.

Why does the calculator only offer half load and full load?

Because those are the only two points Generac publishes. Its spec sheets give a consumption figure at 1/2 load and at full load and nothing in between. Interpolating to a specific percentage would produce a confident-looking number the manufacturer never measured, and an engine's fuel curve is not a straight line. Half load is the realistic setting for backup duty, where a generator is carrying a fraction of what it could.

Does the gas price include my monthly Enbridge charge?

No, deliberately. The figure used here is the marginal rate: what one additional cubic metre costs on top of what your house already burns, which is exactly what a generator adds to a bill. That is the delivery tier plus transportation plus the gas supply commodity charge plus the cost adjustment. Enbridge's $27.69 monthly customer charge is excluded because it does not change when the generator runs, and including a fixed charge in a per-hour figure would overstate the running cost of a short outage badly.

Why is the gas price shown as a range?

Because Enbridge charges delivery in tiers, and which tier your extra cubic metres land in depends on how much gas the house is already using that month. The published band here spans two of Enbridge's own tier rates: 27.95 cents a cubic metre at the over-170 tier and 29.94 at the first-30 tier. Both ends are real published rates rather than a midpoint, and the difference between them on a 24-hour outage is about three dollars.

How much propane does the tank hold, and will it last?

A 500-gallon tank, the size RenoHouse prices for a standby installation, holds roughly 1,900 litres and is normally filled to about 80 percent for expansion, so call it 1,500 usable litres. A 22 kW generator at half load burning 9.57 litres an hour empties that in around 155 hours, or a little over six days of continuous running. Our propane consumption calculator works that out for your own tank size and generator.

Generator Running Cost Calculator (Ontario 2026)

What the fuel costs while it runs

Generator sizeOnly the sizes Generac publishes a consumption figure for. Nothing here is interpolated.FuelHow hard is it working?Half and full are the only two points Generac publishes. Anything between them would be our guess, not their measurement.How long is the outage?hoursA day is 24. An ice-storm outage can run to 72 or more.

Fuel for 24 hours, before HST

$43–$46

6.46 m³ an hour at half load, from Generac's published spec sheet for this size, times 155 m³ of fuel. With the 13 percent HST that is $49–$52.

Consumption at half load (Generac spec sheet): 6.46 m³/h
Fuel used over the outage: 155 m³
Marginal price per cubic metre (Enbridge Rate 1, July 1 2026): $0.2795–$0.2993
Cost per hour of running: $1.81–$1.93
Total fuel for the outage, with HST: $49–$52

The gas price is a marginal rate: what one extra cubic metre costs on top of what the house already burns, which is what a generator adds. Enbridge's $27.69 monthly customer charge is excluded because it does not change when the generator runs. The band spans Enbridge's own first and top delivery tiers rather than a midpoint between them.

Why the gas figure is a marginal rate, not your bill divided by usage

A generator does not create a new gas account. It adds cubic metres on top of whatever the house was already burning, so the only question that matters is what the NEXT cubic metre costs. That is Enbridge's delivery charge for the tier those metres land in, plus transportation at 5.4267 cents, plus the gas supply commodity charge at 10.3025, minus the current cost adjustment of 0.1686. It comes to 27.95 cents a cubic metre in the top delivery tier and 29.94 in the first.

Two charges are deliberately left out. The $27.69 monthly customer charge does not move when the generator runs, and folding a fixed monthly fee into a per-hour figure would make a two-hour outage look like it cost thirty dollars of gas. The facility carbon charge of 0.0145 cents is excluded because Enbridge's own rate notice says it is already inside the delivery figure, so counting it separately would be counting it twice.

The table is not a smooth curve, and it is published as measured

Read down Generac's consumption figures and something looks wrong: a 16 kW unit burns 6.17 cubic metres an hour at half load, and an 18 kW unit burns 4.79. The bigger machine uses less. The same happens at the top, where a 26 kW unit is thirstier than a 22 at full load but leaner at half.

Those are different engines with different tuning, tested separately, and the figures are what Generac published for each. Smoothing them into a tidy line rising with kW would replace a manufacturer's measurement with our own curve, which is the exact thing this register does not do with a sourced number. If your shortlist spans those sizes, it is worth knowing that a slightly larger unit is not automatically the thirstier one.

What this page cannot tell you is what the machine costs to own. The maintenance cost guide covers the annual service visit, and the worth-it checker puts fuel, servicing and the install against what outages actually cost you. For a propane tank specifically, the propane consumption calculator works out how many days a fill lasts.

Frequently asked questions

How much does it cost to run a generator for 24 hours?: On natural gas, far less than most people expect. A 22 kW Generac Guardian burns 6.46 cubic metres an hour at half load per its spec sheet, so a 24-hour outage uses about 155 cubic metres. At Enbridge's Rate 1 marginal rate of roughly 28 to 30 cents a cubic metre that is $43 to $46 of gas before HST. The same machine on propane burns 9.57 litres an hour, which at $0.70 to $0.95 a litre comes to $161 to $218 for the same day.
Why is propane so much more expensive to run than natural gas?: Because you are buying energy at retail in a truck instead of through a pipe. On the same 22 kW machine over the same 24 hours at half load, natural gas costs about $43 at the low end and propane about $161, roughly four times as much. That gap is the strongest argument for running a gas line to the generator wherever an Enbridge main is available, and it compounds: a house that sees three multi-day outages a year is paying that difference every time.
Why does the calculator only offer half load and full load?: Because those are the only two points Generac publishes. Its spec sheets give a consumption figure at 1/2 load and at full load and nothing in between. Interpolating to a specific percentage would produce a confident-looking number the manufacturer never measured, and an engine's fuel curve is not a straight line. Half load is the realistic setting for backup duty, where a generator is carrying a fraction of what it could.
Does the gas price include my monthly Enbridge charge?: No, deliberately. The figure used here is the marginal rate: what one additional cubic metre costs on top of what your house already burns, which is exactly what a generator adds to a bill. That is the delivery tier plus transportation plus the gas supply commodity charge plus the cost adjustment. Enbridge's $27.69 monthly customer charge is excluded because it does not change when the generator runs, and including a fixed charge in a per-hour figure would overstate the running cost of a short outage badly.
Why is the gas price shown as a range?: Because Enbridge charges delivery in tiers, and which tier your extra cubic metres land in depends on how much gas the house is already using that month. The published band here spans two of Enbridge's own tier rates: 27.95 cents a cubic metre at the over-170 tier and 29.94 at the first-30 tier. Both ends are real published rates rather than a midpoint, and the difference between them on a 24-hour outage is about three dollars.
How much propane does the tank hold, and will it last?: A 500-gallon tank, the size RenoHouse prices for a standby installation, holds roughly 1,900 litres and is normally filled to about 80 percent for expansion, so call it 1,500 usable litres. A 22 kW generator at half load burning 9.57 litres an hour empties that in around 155 hours, or a little over six days of continuous running. Our propane consumption calculator works that out for your own tank size and generator.

Where these figures come from

Consumption straight off Generac's own spec-sheet PDFs, in metric, with each column matched to its model against the breaker and unit-weight rows on the same sheet rather than assumed from left to right. Gas prices from Enbridge's published Rate 1 notice for Toronto, Ottawa and Niagara effective 1 July 2026. Propane from a named Ontario supplier, and taken as your own input where you have a delivery contract, because no government or utility source in Canada publishes a residential delivered propane rate. Home Generator Index multiplies those two published numbers together and does nothing else to them.

Generator Running Cost: What the Fuel Bill Looks Like