Skip to content
CampingCalc

Fuel Cost and Fuel Economy Calculator for RVs and campers

1,000 miles at 10 mpg is 100 gallons – at $3.60/gal about $360. This calculator optionally determines your fuel economy from fill-up data and shows fuel amount, cost per trip and per 100 miles as well as the savings at lower speed.

Units

Camper vans 14–18 mpg, Class C 8–10 mpg, Class A 6–8 mpg (rules of thumb).

Example value (EIA 2025 average) – enter the current price.

Comparison (optional)

0 = no comparison. Driving slower often saves 15–25% with motorhomes.

Result

Fuel cost for the trip

$152.51

42 gal at 22 mpg

Fuel economy
22 mpg
Cost per 100 mi
$16.36
Cost per mi
0.164 $/mi
CO₂ emissions (combustion)
937 lb
Show calculation
  1. 1Fuel: 932 mi ÷ 22 mpg = 42.4 gal
  2. 2Cost: 42.4 gal × $0.95 = $152.51
  3. 3Per 100 mi: 100 ÷ 22 mpg × $0.95 = $16.36

 

How it's calculated

Fuel economy [mpg] = miles driven ÷ gallons filled Fuel [gal] = distance ÷ mpg Cost = gallons × price; cost per 100 mi = 100 ÷ mpg × price
165 mi ÷ 16.5 gal = 10 mpg

To determine fuel economy, always fill up completely, note the odometer and enter gallons and distance at the next full fill-up. Averaging several fill-ups gives a reliable value.

The CO₂ emissions refer to combustion (diesel about 22.4 lb/gal = 2.65 kg/L, gasoline about 19.6 lb/gal = 2.37 kg/L) without the upstream chain of fuel production.

Worked example

After 165 miles, 16.5 gallons were refilled. What does the planned 1,250-mile trip cost at $3.60/gal, and what does slower driving at 12 mpg save?

Inputs

  • Fuel economy: Determine from fill-up data (gallons and miles since last full fill-up)
  • Amount filled (full → full): 16.5 gal
  • Distance driven since last full fill-up: 165 mi
  • Planned distance: 1,250 mi
  • Fuel price: 3.6 $/gal
  • Fuel: Diesel
  • Comparison fuel economy (e.g. at 60 instead of 70 mph): 12 mpg

Result

$450.07

Fuel cost for the trip

Fuel economy
10 mpg
Cost per 100 mi
$36.01
Cost per mi
0.36 $/mi
CO₂ emissions (combustion)
2,765 lb
Savings with comparison fuel economy
$75.10

Calculation

  1. Fuel economy: 165 mi ÷ 16.5 gal = 10 mpg
  2. Fuel: 1,250 mi ÷ 10 mpg = 125 gal
  3. Cost: 125 gal × $0.95 = $450.07
  4. Per 100 mi: 100 ÷ 10 mpg × $0.95 = $36.01
  5. Comparison: 104.2 gal → savings $75.10

The variables explained

Fuel economy (mpg)
Real average fuel economy; for motorhomes strongly dependent on speed, load, wind and terrain.
Fuel price ($/gal)
Current price; varies considerably between states.
Comparison fuel economy
For estimating savings potential (speed, cargo box, tire pressure).

Common mistakes

  • Using the manufacturer's EPA figure – motorhomes really get 20–40% worse.
  • Trusting the trip computer blindly – it often shows 5–10% too optimistic.
  • Underestimating consumption in headwind and at highway speed.

Assumptions and limits

  • Constant fuel economy over the distance.
  • CO₂ factors as common averages for combustion.