In this case, “20-mile commute” means 20 miles round trip: 10 miles to work and 10 miles home. The driver commutes five days a week for 48 weeks each year, allowing four weeks for vacation, holidays, illness, and other non-commuting days.
The inputs
- Round-trip distance: 20 miles
- Commute days: 5 per week × 48 weeks = 240 days
- Vehicle fuel economy: 28 miles per gallon
- Fuel price: $3.50 per gallon
- Maintenance and wear allowance: $0.10 per mile
- Parking and tolls: $0 in this example
The $0.10-per-mile wear allowance is a planning assumption, not a universal rate. It represents routine maintenance and gradual tire wear; it does not claim to capture depreciation, financing, insurance, major repairs, or every ownership cost.
Step 1: Find annual miles
5 days × 48 weeks = 240 days
Annual commute miles
20 miles × 240 days = 4,800 miles
Step 2: Find fuel cost
4,800 miles ÷ 28 mpg = 171.43 gallons
Fuel cost
171.43 gallons × $3.50 = $600.00
The exact unrounded gallons are used before rounding the final cost. Because 4,800 ÷ 28 × 3.50 equals exactly 600, this example has no rounding difference.
Step 3: Add a maintenance and wear allowance
$600 fuel + $480 wear allowance = $1,080 per year
Over five years with the same schedule, prices, and vehicle, the result is $1,080 × 5 = $5,400. Real life will not stay that still: fuel prices, work schedules, mileage, repairs, and vehicles change.
What two work-from-home days change
If the driver commutes three days instead of five, annual commute days fall from 240 to 144. The same formulas produce 2,880 annual miles, $360 in fuel, and $288 in the wear allowance.
| Schedule | Days/year | Miles/year | Estimated cost |
|---|---|---|---|
| 5 office days/week | 240 | 4,800 | $1,080 |
| 3 office days/week | 144 | 2,880 | $648 |
| Difference | 96 fewer | 1,920 fewer | $432 less |
The $432 is reduced vehicle-use spending under the stated assumptions. It does not include possible home-office costs, transit fares, or changes in insurance. It also does not place a dollar value on the 96 round trips avoided.
How sensitive is the answer?
- If gas rises to $4.50: fuel becomes $771.43 and the annual total becomes $1,251.43.
- If the vehicle gets 35 mpg: fuel becomes $480 and the annual total becomes $960.
- If parking costs $8 per day: add $1,920 a year, raising the total to $3,000.
- If “20 miles” means one way: double the annual miles and distance-based costs before adding fixed daily fees.
Costs this example leaves out
Insurance, registration, vehicle payments, depreciation, accident risk, major repairs, and the value of travel time are excluded. Some are ownership costs you may pay even if you do not commute; others can change with mileage. Keep them separate unless you have a defensible way to allocate them to work travel.
Questions people ask
Should I use city or highway MPG?
Use the figure that best matches your route, or use the combined estimate when the trip is mixed. Your dashboard average or several tanks of actual fuel records can be more representative.
What if my schedule changes every week?
Estimate total commute days for the month or year instead of forcing a weekly pattern. Then multiply actual days by round-trip miles.
Is the wear allowance the same as the IRS mileage rate?
No. This page uses a narrow illustrative allowance for maintenance and tire wear. A broad mileage rate may include categories beyond this case study and should not be substituted without understanding what it represents.
Does less commuting equal cash saved immediately?
Fuel, tolls, and parking may change quickly. Maintenance and vehicle replacement effects arrive more gradually, so treat them as planning estimates rather than immediate cash.
Sources and further help
Check official vehicle fuel-economy estimates and compare models at FuelEconomy.gov, a U.S. Department of Energy and Environmental Protection Agency resource. The site also explains why actual mileage can differ from laboratory estimates. For the broader decision process, read The costs beyond gasoline.
Replace every assumption with your numbers
Enter your distance, schedule, fuel economy, fuel price, parking, tolls, and wear estimate.
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