How Mixed Driving MPG Calculator Works?
This tool works by blending city and highway miles per gallon (MPG) with a harmonic average weighted by your city driving share. The result is your expected combined MPG.
Enter the city share
Type the percentage of miles driven in the city. The EPA combined rating uses 55%.
Enter city MPG
Type the city rating, for example 24 MPG.
Enter highway MPG
Type the highway rating, for example 34 MPG.
Read the blended MPG
The tool returns combined MPG for your driving mix.
Mixed Driving MPG Calculator Formula
The formula is Blended MPG = 1 ÷ ((City % ÷ 100 ÷ City MPG) + (Highway % ÷ 100 ÷ Highway MPG)).
Blended MPG = 1 ÷ ((City Share ÷ City MPG) + (Highway Share ÷ Highway MPG))Formula variables
- City Share
- Fraction of miles driven in the city.
- Highway Share
- 1 minus the city share.
- City MPG, Highway MPG
- Fuel economy ratings for each road type.
Worked example
- City Driving % Share: 55%
- City MPG Rating: 24 MPG
- Highway MPG Rating: 34 MPG
- City part: 0.55 ÷ 24 = 0.02292 gallons per mile.
- Highway part: 0.45 ÷ 34 = 0.01324 gallons per mile.
- Blended MPG: 1 ÷ (0.02292 + 0.01324) = 27.66 MPG.
Result: 27.66 (Blended MPG)
A simple average gives 28.5 MPG, which overstates real economy. The harmonic average weights each mile correctly, since fuel use adds up per mile, not per MPG point.
Mixed Driving MPG Calculator Conversion Table
The table shows blended MPG for 5 city shares at 3 highway ratings, with city MPG fixed at 24.
Rows: City Driving % Share (%). Columns: Highway MPG Rating (MPG). Cells: Blended MPG.
| % | 30 MPG | 34 MPG | 40 MPG |
|---|---|---|---|
| 0% | 30.00 | 34.00 | 40.00 |
| 25% | 28.24 | 30.79 | 34.29 |
| 55% | 26.37 | 27.66 | 29.27 |
| 75% | 25.26 | 25.90 | 26.67 |
| 100% | 24.00 | 24.00 | 24.00 |
Values held constant: City MPG Rating = 24 MPG.
At 0% city driving the result equals the highway rating, and at 100% city driving the result equals the 24 MPG city rating.
What is Mixed Driving MPG Calculator?
The Mixed Driving MPG Calculator is a tool that estimates combined fuel economy for your own mix of city and highway driving. The tool personalizes the EPA combined rating.
The EPA combined figure assumes 55% city and 45% highway driving. A rural commuter driving 20% city or an urban driver at 80% city gets a different real figure.
The harmonic method used here matches how the EPA calculates its own combined rating.
What are the uses of Mixed Driving MPG Calculator?
There are 4 main uses of the Mixed Driving MPG Calculator: personalizing fuel economy estimates, comparing vehicles for your routes, feeding cost calculators, and checking dashboard averages.
Personalizing fuel economy estimates
Drivers replace the EPA combined figure with a custom blend.
Comparing vehicles for your routes
Buyers compare 2 cars at their own city share.
Feeding cost calculators
The blended MPG improves monthly and annual cost estimates.
Checking dashboard averages
Owners compare the blended estimate with the trip computer.
Need every metric in one place? Open the main MPG Cost Calculator or browse all 101 fuel calculators.