Right now, gasoline prices are at their highest levels since 2014 and are expected to continue rising through Memorial Day to more than $3 per gallon in some areas, according to GasBuddy analysts.

If you’re trying to save as much money as you can, you may want to change the day of the week that you fill up.

After analyzing gas price data from January through March, GasBuddy reports that Mondays offer the lowest average gas price in 21 states — making it the best day of the week to buy gas.

Meanwhile, Friday is the worst day to buy gas in 19 states, having the most expensive average.

“Though there is variation in daily gas prices across different states, the consensus is that the earlier motorists fill-up during the week, the better,” says Patrick DeHaan, head of petroleum analysis at GasBuddy. “Following Monday, Sunday is the cheapest day to fill-up. Conversely, Thursday follows Friday as the most expensive day to fill-up.”

Friday isn’t only the overall most expensive day to buy gas, it’s also the busiest. GasBuddy suggests that you fill up on Sundays to avoid the long lines.

Here are the best and worst days to buy gas in all 50 states:
State Most Expensive Least Expensive
Alaska Friday Sunday
Alabama Friday Monday
Arkansas Thursday Monday
Arizona Saturday Sunday
California Friday Tuesday
Colorado Friday Sunday
Connecticut Monday Saturday
Washington, DC Saturday Wednesday
Delaware Friday Monday
Florida Saturday Monday
Georgia Thursday Sunday
Hawaii Friday Sunday
Iowa Thursday Monday
Idaho Thursday Sunday
Illinois Friday Monday
Indiana Thursday Monday
Kansas Friday Wednesday
Kentucky Thursday Monday
Louisiana Friday Monday
Massachusetts Friday Monday
Maryland Sunday Monday
Maine Saturday Tuesday
Michigan Saturday Tuesday
Minnesota Friday Tuesday
Missouri Saturday Monday
Mississippi Friday Monday
Montana Monday Saturday
North Carolina Saturday Sunday
North Dakota Thursday Tuesday
Nebraska Friday Sunday
New Hampshire Thursday Sunday
New Jersey Saturday Monday
New Mexico Thursday Tuesday
Nevada Saturday Tuesday
New York Thursday Wednesday
Ohio Thursday Monday
Oklahoma Friday Monday
Oregon Thursday Sunday
Pennsylvania Friday Monday
Rhode Island Sunday Monday
South Carolina Friday Wednesday
South Dakota Friday Sunday
Tennessee Thursday Monday
Texas Wednesday Monday
Utah Friday Sunday
Virginia Friday Sunday
Vermont Friday Monday
Washington State Saturday Tuesday
Wisconsin Friday Monday
West Virginia Saturday Sunday
Wyoming Monday Saturday