FUEL COST AND DETOUR WORKSHEET
Yenra | Updated September 7, 2026
Article: https://yenra.com/gas-prices/

Purpose: estimate gasoline spending and fuel-only detour savings. Save and edit this text file. Units below are miles, U.S. gallons, miles per gallon (mpg) and U.S. dollars. All sample values are fictional, not current price quotations.

Vehicle/engine and manual reference:
Required octane and supported fuel blend:
Price observation date, location and source:
Grade/blend and cash/credit/membership conditions:

TRIP OR MONTHLY COST
Distance D (miles):
Realistic economy E (mpg), with evidence:
Fuel price P ($/U.S. gallon):
Fuel needed = D / E (gallons):
Fuel cost = D / E x P ($):
Cost per mile = P / E ($/mile):
Lower-MPG or higher-price case and result:
Fictional example: 360 / 30 = 12 gallons; 12 x $3.50 = $42. At 24 mpg: 15 gallons and $52.50. Fuel cost excludes tolls, maintenance, insurance and other vehicle costs.

DETOUR
Planned purchase Q (gallons):
Price difference S ($/gallon), after conditions:
Entire extra route d (miles, including return/rejoin):
Detour fuel economy E (mpg):
Price used to value extra fuel P ($/gallon):
Gross saving = Q x S ($):
Extra fuel expense = d / E x P ($):
Fuel-only saving = Q x S - d / E x P ($):
Fuel-only break-even extra distance = Q x S x E / P (miles):
Extra time, tolls and other costs:
Fictional example: 12 gallons x $0.15 = $1.80; extra 6 miles / 30 mpg x $3.50 = $0.70; fuel-only saving $1.10. Break-even extra distance about 15.4 miles total.

Use positive MPG and fuel price in these formulas. Use a supported fuel grade. Actual costs vary with route, conditions and the price paid. Decision and assumptions to revisit:

REFERENCE CONTEXT
The linked article explains the comparisons and limits. Check exact project or equipment documents before using a specification.
EIA gasoline and diesel update
https://www.eia.gov/petroleum/gasdiesel/
gasoline survey methodology
https://www.eia.gov/petroleum/gasdiesel/gas_proc-methods.php
DOE/EPA guidance on octane
https://www.fueleconomy.gov/feg/octane.shtml
EIA’s price-component explanation
https://www.eia.gov/energyexplained/gasoline/factors-affecting-gasoline-prices.php
EIA’s explanation of price fluctuations
https://www.eia.gov/energyexplained/gasoline/price-fluctuations.php