PHEV Economy Calculator — Combined MPGe & Fuel Cost
Enter your PHEV's all-electric range, daily driving distance, electric efficiency and hybrid-mode fuel economy to see your real-world combined MPGe, the share of miles driven on electricity each day, and the annual cost of electricity vs gasoline.
Distance unit
mi
mi
kWh / 100 mi
MPG
$ / kWh
$ / gal
75% of daily distance covered by electricity
75%
Electric shareEV miles
75%
HV miles
25%
- 1
Utility factor (EV fraction of daily trip)
min(30 ÷ 40, 1) = 0.75Fraction of each day driven on electricity. - 2
EV miles per day
0.75 × 40 = 30 - 3
HV miles per day
40 − 30 = 10 - 4
Daily fuel cost
(30 × 30 ÷ 100 × 0.14) + (10 ÷ 40 × 3.5) = 2.135 - 5
Annual fuel cost
2.135 × 365 = 779
How does this calculator work?
PHEV daily cost = (EV miles × kWh/100mi ÷ 100) × $/kWh + (HV miles ÷ MPG_hybrid) × $/gal. If your EV range covers your whole commute, nearly all fuel cost is electricity. Combined MPGe = daily miles ÷ (electric kWh ÷ 33.7 + gasoline gallons). Energy prices used are 2025 US averages; edit to match your rates.
Formula
How this is calculated
A plug-in hybrid operates in two modes: all-electric (EV mode) for up to its rated electric range, then gasoline-hybrid (HV mode) for longer trips. The key figure is the utility factor (UF) — the fraction of daily miles driven in EV mode. For a single daily trip, UF = min(EV range / daily miles, 1.0): if your daily distance is within the electric range, you run entirely on electricity; beyond it, the gasoline engine covers the remainder.
The combined miles-per-gallon equivalent (MPGe) follows the EPA's energy-equivalence principle: 1 gallon of gasoline contains approximately 33.7 kWh of energy. The daily electricity consumption (kWh) is converted to a "gallon equivalent" and added to actual gallons used in HV mode; dividing total daily distance by total gallon equivalents gives MPGe.
Annual fuel costs are computed by scaling the daily electricity cost (kWh used × $/kWh) and gasoline cost (gallons used × $/gallon) over 365 days. This model uses a single-trip UF — real-world UF depends on trip length distribution and charging habits. The EPA uses the SAE J2841 statistical UF table for official PHEV labels; this calculator uses the simpler single-trip approximation, which tends to overstate EV use for drivers with irregular trips.
Frequently asked questions
MPGe (miles per gallon equivalent) converts electric energy to a gasoline-energy basis using the EPA factor of 33.7 kWh per gallon. For a PHEV, total daily energy = electricity kWh + gasoline gallons × 33.7; MPGe = daily miles ÷ (total kWh ÷ 33.7). This lets you compare PHEVs and EVs on the same scale as conventional cars.
The EPA PHEV label uses the SAE J2841 statistical utility factor, weighted over a large US driving-distance distribution. If you drive more than the EV range daily — or rarely charge — your real-world UF is lower and you use more gasoline. Conversely, if most of your trips are shorter than the EV range and you charge every night, you may beat the EPA figure.
Yes. Cold weather (below ~15°C / 59°F) reduces battery capacity and increases cabin heating load, shrinking the effective EV range by 15–40% on some models. Hot weather increases air-conditioning load. The calculator uses your entered EV range as-is — reduce it by 20–30% in winter to get a more realistic cold-weather estimate.
Also known as
TG we-Calculate Editorial Team. (2026). PHEV Economy Calculator — Combined MPGe & Fuel Cost [Online calculator]. TG we-Calculate. https://we-calculate.com/calculator/phev-economy-calculator
TG we-Calculate Editorial Team. "PHEV Economy Calculator — Combined MPGe & Fuel Cost." TG we-Calculate. 2026. https://we-calculate.com/calculator/phev-economy-calculator.
TG we-Calculate Editorial Team, "PHEV Economy Calculator — Combined MPGe & Fuel Cost," TG we-Calculate, 2026. [Online]. Available: https://we-calculate.com/calculator/phev-economy-calculator
@misc{wecalculate_phev_economy_calculator, title = {PHEV Economy Calculator — Combined MPGe & Fuel Cost}, author = {{TG we-Calculate Editorial Team}}, howpublished = {\url{https://we-calculate.com/calculator/phev-economy-calculator}}, year = {2026}, note = {TG we-Calculate} }
Did this calculator help you?