The short answer
Keeping an attached 2-car garage with insulated walls and ceiling at 50°F all winter costs about $260.70 a year with a natural gas unit heater, $491.17 with propane and $750.03 with an electric heater, at U.S. average prices (August 2026) and climate. In Minnesota the same garage costs $426.62 on gas; in Texas, $51.18.
The same garage in every state
This garage at 50°F, 24 hours a day, 7 days a week, in each state's climate at its electricity, gas and propane prices.
| Alabama | $201.46 | $88.92 | $199.07 | 16.33¢ |
|---|---|---|---|---|
| Alaska | $3,131.73 | $567.70 | $1,266.36 | 29.41¢ |
| Arizona | $93.54 | $47.45 | $73.92 | 15.05¢ |
| Arkansas | $294.69 | $162.68 | $223.79 | 14.37¢ |
| California | $268.57 | $81.62 | $107.36 | 29.75¢ |
| Colorado | $1,116.78 | $299.60 | $673.40 | 17.17¢ |
| Connecticut | $1,261.07 | $355.49 | $919.01 | 24.51¢ |
| Delaware | $627.45 | $220.38 | $558.64 | 18.70¢ |
| District of Columbia | $904.16 | $238.97 | $543.72 | 25.98¢ |
| Florida | $22.43 | $15.70 | $32.59 | 14.99¢ |
| Georgia | $208.10 | $109.96 | $187.99 | 15.90¢ |
| Hawaii | $0.03 | $0.01 | $0.01 | 47.18¢ |
| Idaho | $821.21 | $193.85 | $676.02 | 13.37¢ |
| Illinois | $1,107.60 | $266.51 | $510.66 | 19.32¢ |
| Indiana | $846.51 | $235.46 | $572.92 | 17.02¢ |
| Iowa | $1,170.70 | $298.53 | $508.85 | 17.06¢ |
| Kansas | $615.25 | $242.56 | $352.41 | 15.47¢ |
| Kentucky | $445.42 | $188.59 | $401.91 | 13.80¢ |
| Louisiana | $72.01 | $40.09 | $75.41 | 12.87¢ |
| Maine | $2,521.37 | $612.87 | $1,204.81 | 32.11¢ |
| Maryland | $744.77 | $231.55 | $582.67 | 21.40¢ |
| Massachusetts | $1,677.56 | $568.06 | $875.27 | 30.48¢ |
| Michigan | $1,492.01 | $290.63 | $684.02 | 22.99¢ |
| Minnesota | $1,623.12 | $426.62 | $858.19 | 17.20¢ |
| Mississippi | $145.57 | $69.27 | $142.09 | 14.43¢ |
| Missouri | $657.87 | $252.21 | $402.18 | 16.02¢ |
| Montana | $1,309.67 | $312.11 | $792.41 | 15.57¢ |
| Nebraska | $806.52 | $279.45 | $447.25 | 13.54¢ |
| Nevada | $246.37 | $104.91 | $230.34 | 12.72¢ |
| New Hampshire | $2,058.02 | $571.62 | $1,243.14 | 27.64¢ |
| New Jersey | $1,041.62 | $247.31 | $716.52 | 24.61¢ |
| New Mexico | $515.27 | $126.45 | $420.64 | 16.51¢ |
| New York | $1,536.53 | $388.85 | $882.91 | 28.65¢ |
| North Carolina | $281.57 | $126.92 | $295.12 | 14.95¢ |
| North Dakota | $1,387.36 | $408.99 | $792.36 | 13.31¢ |
| Ohio | $967.66 | $285.36 | $600.78 | 19.38¢ |
| Oklahoma | $337.74 | $135.10 | $235.94 | 14.82¢ |
| Oregon | $522.87 | $225.53 | $390.59 | 15.92¢ |
| Pennsylvania | $1,076.88 | $305.91 | $675.93 | 21.77¢ |
| Rhode Island | $1,396.04 | $441.59 | $838.67 | 28.18¢ |
| South Carolina | $179.01 | $78.96 | $181.16 | 15.76¢ |
| South Dakota | $1,196.30 | $319.94 | $659.18 | 15.15¢ |
| Tennessee | $321.29 | $116.41 | $351.71 | 13.42¢ |
| Texas | $102.09 | $51.18 | $87.98 | 15.91¢ |
| Utah | $847.08 | $266.01 | $679.68 | 13.31¢ |
| Vermont | $1,989.37 | $619.27 | $1,436.02 | 23.84¢ |
| Virginia | $527.64 | $206.67 | $482.66 | 17.64¢ |
| Washington | $542.16 | $268.69 | $440.71 | 14.63¢ |
| West Virginia | $653.61 | $227.32 | $639.17 | 16.31¢ |
| Wisconsin | $1,501.53 | $343.13 | $689.08 | 19.41¢ |
| Wyoming | $1,177.61 | $393.31 | $833.50 | 14.43¢ |
How it works
The formula
heat a month = heat loss per °F × degree days below your setting × 24 × share of time heated
fuel = heat ÷ (3,412 BTU per kWh; or 80% × 100,000 per therm, × 91,452 per gallon of propane)
Assumptions
- Heat loss: the same figures as our garage heater size calculator on SizeSums: insulated walls U 0.075 (R-13) and ceiling U 0.033 (R-30), uninsulated walls U 0.25 and ceiling U 0.3, a steel garage door U 1.1 (0.35 insulated), 0.8 BTU/h per °F per foot of slab edge, and 0.5 to 1 air change an hour. An attached garage loses nothing through the wall it shares with the house.
- Degree days at your setting come from NOAA's 1991–2020 monthly normals for your state. NOAA counts degree days below 65°F, so we use the variable-base method of Erbs, Klein and Beckman (1983), which estimates degree days at any base from the month's average temperature and how much daily temperatures vary around it. Where the month's 65°F figures are big enough to pin that variation down, we fit it so the method gives back NOAA's own number; where they aren't (months almost always warmer or colder than 65°F), we use the authors' published estimate of it, blending smoothly between the two.
- Heaters: electric heaters turn all their power into heat; a vented gas or propane unit heater is taken as 80% efficient.
- Part-time heating is the share of hours you heat. Warming a cold garage's slab and contents takes extra heat that this leaves out, so short sessions cost a little more.
Worked example: an attached 2-car garage at 50°F
22 × 22 ft, 9 ft ceiling, insulated walls and ceiling, a plain 16 ft door, U.S. averages
- Heat loss: 275 BTU an hour per °F
- 275 × 2,134 degree days below 50°F a year × 24 h = 14,092,058 BTU
- Electric: ÷ 3,412 = 4,130 kWh × 18.16¢ = $750.03; gas: ÷ 0.8 ÷ 100,000 = 176 therms = $260.70
Ways to cut the cost
- Insulate and seal the garage door once the walls and ceiling are insulated: then the plain door loses more heat than all the walls. In an uninsulated garage, start with the ceiling and walls.
- Turn it down when you're not in it: 40°F keeps pipes safe for far less than 50°F or 60°F.
- Use a thermostat, not a heater left on high.
- Vent gas and propane heaters outdoors and fit a carbon monoxide alarm; never use an unvented heater with the door shut.
Questions people ask
How much does it cost to heat a garage?
Keeping an attached 2-car garage with insulated walls at 50°F all winter costs about $750.03 a year with an electric heater, $260.70 with a natural gas unit heater and $491.17 with propane at U.S. average prices and climate. Climate matters most: $426.62 on gas in Minnesota, $51.18 in Texas.
Is it cheaper to heat a garage with gas or electric?
Usually gas, where you have it: a gas unit heater at 80% efficiency costs about $260.70 a year for this garage against $750.03 for electric at U.S. averages. Propane falls in between. Your state's prices decide it; the table below compares them.
How much does it cost to heat a garage workshop on weekends?
Heating the same garage to 60°F for 4 hours, 2 days a week, costs about $66.80 a year electric and $23.22 on gas. Warming up a cold garage takes extra heat the first hour, so short sessions cost a bit more than this.
Does insulating the garage door save money?
Once the walls are insulated, the plain steel door is the biggest single heat loss. An uninsulated garage costs about $1,417.68 a year to keep at 50°F electric, against $750.03 with insulated walls and ceiling; an insulated door cuts it further. Try the options above.
What temperature should I keep my garage in winter?
Above freezing (40°F) protects water pipes, paint and batteries; 50°F is comfortable for working in a coat; 60°F or more for a workshop. Every degree lower saves money, most in mild months.