MPG · L/100km · km/L · Fill-up Tracker
Gas Mileage
Calculator
Calculate your actual MPG from odometer readings or miles driven and gallons used. Track multiple fill-ups, convert units, and compare against your EPA rating.
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Input modes
MPG
L/100km·km/L
Log
Multi fill-up
EPA
Comparison
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Gas Mileage Calculator
Calculate your real-world MPG
Fill tank → note odometer → drive → fill again → enter both readings + gallons used.
mi
mi
$/gal
mpg
$/gal
mpg
Track multiple fill-ups — shows average MPG
Fill-up
Miles
Gallons
$/gal
Fuel Efficiency Converter
Convert MPG ↔ L/100km ↔ km/L
Enter any value — the other two convert instantly.
US Miles Per Gallon
MPG (US)
Liters per 100 km
L/100km
Kilometers per Liter
km/L
Also: — UK MPG · — cost/mile at $3.50/gal
MPG Reference
What Is Good Gas Mileage?
EPA combined MPG benchmarks by vehicle class. Higher is better for gas vehicles.
| Vehicle Class | Typical MPG | L/100km | Rating | Fuel Cost/Mile* |
|---|---|---|---|---|
| Hybrid sedan (2024) | 40–58 MPG | 4.1–5.9 | 🟢 Excellent | 6–9¢/mile |
| Compact car | 30–38 MPG | 6.2–7.8 | 🟢 Very Good | 9–12¢/mile |
| Mid-size sedan | 26–32 MPG | 7.4–9.0 | 🟡 Good | 11–13¢/mile |
| Small SUV / crossover | 26–34 MPG | 6.9–9.0 | 🟡 Good | 10–13¢/mile |
| Mid-size SUV | 20–26 MPG | 9.0–11.8 | 🟠 Average | 13–18¢/mile |
| Full-size pickup truck | 16–22 MPG | 10.7–14.7 | 🔴 Low | 16–22¢/mile |
| Performance/sports car | 15–25 MPG | 9.4–15.7 | 🔴 Low–Average | 14–23¢/mile |
| Electric (MPGe) | 100–130 MPGe | — | 🟢 Best | 3–5¢/mile |
*Based on $3.50/gallon or $0.17/kWh for EV.
Fuel Economy Tips
How to Improve Your Gas Mileage
Proven techniques that can meaningfully increase your real-world MPG.
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Slow Down on Highways
Aerodynamic drag increases with the square of speed. Each 5 mph over 60 costs 7–14% more fuel. Driving 65 instead of 75 mph saves about 10–15% — often the single largest MPG improvement available.
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Smooth Acceleration
Aggressive acceleration and hard braking wastes 15–30% more fuel in city driving. Anticipate traffic, coast to stops, and accelerate gradually. Use cruise control on highways to maintain a steady speed.
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Maintain Tire Pressure
Under-inflated tires increase rolling resistance. Tires lose ~1 PSI/month naturally, and 1 PSI per 10°F temperature drop. Correct tire pressure improves MPG by up to 3% and extends tire life significantly.
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Regular Maintenance
A dirty air filter reduces airflow to the engine. Worn spark plugs cause incomplete combustion. The wrong motor oil increases internal friction. These individually cost 1–4% MPG each — combined, 5–10% improvement is possible.
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Reduce Weight & Drag
Remove roof racks and cargo carriers when not in use — they add aerodynamic drag even when empty. Extra weight in the trunk costs 1–2% MPG per 100 lbs. Clean out items that live permanently in your trunk.
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Manage A/C and Cold Starts
A/C reduces MPG by 5–25% depending on conditions — it's most impactful in city driving. At low speeds, opening windows is more efficient. Cold engines use more fuel — combine short trips or park in a garage in winter.
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City vs Highway MPGConventional gas cars get 25–35% better MPG on the highway than in city driving. City driving involves frequent stops, idling, and acceleration from rest — all fuel-intensive activities.
The EPA's combined rating (55% city / 45% highway) attempts to reflect typical driving. For mostly highway commuters, your real MPG may be higher than the combined EPA rating; for city commuters, it will be lower. Hybrids reverse this — better in city (regenerative braking).
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US MPG vs UK MPG vs L/100kmThe US uses US gallons (3.785 L), while the UK uses Imperial gallons (4.546 L). A UK gallon is 20% larger, so UK MPG ratings are 20% higher than US MPG for the same vehicle. Always check which standard is used before comparing.
Europe and much of the world uses L/100km — lower is better. A 30 US MPG car = 7.84 L/100km. A 50 MPG hybrid = 4.7 L/100km. Use our converter above to switch between any unit system instantly.
How to Calculate Gas Mileage — Step by Step
Calculating your actual gas mileage is simple and only requires a pen, your odometer, and your gas pump receipt. Doing this consistently reveals your real-world fuel economy and helps catch mechanical problems early.
Method 1: From Odometer Readings
Step 1: Fill tank to full. Note odometer reading (A).
Step 2: Drive as you normally would.
Step 3: Fill tank again. Note:
- New odometer reading (B)
- Gallons added to refill (G)
MPG = (B - A) / G
Example:
A = 48,230 miles; B = 48,542 miles; G = 11.5 gallons
Miles driven = 48,542 - 48,230 = 312 miles
MPG = 312 / 11.5 = 27.1 MPG
Tip: Repeat 3-4 times for a reliable average.
Different pump nozzles and tank angle can affect gallons.
Fuel Efficiency Unit Conversions
US MPG → L/100km: L/100km = 235.214 / MPG
US MPG → km/L: km/L = MPG * 0.425144
US MPG → UK MPG: UK MPG = MPG * 1.20095
L/100km → US MPG: MPG = 235.214 / L/100km
km/L → US MPG: MPG = km/L / 0.425144
Quick reference:
20 MPG = 11.76 L/100km = 8.50 km/L
25 MPG = 9.41 L/100km = 10.63 km/L
30 MPG = 7.84 L/100km = 12.75 km/L
35 MPG = 6.72 L/100km = 14.88 km/L
40 MPG = 5.88 L/100km = 17.00 km/L
50 MPG = 4.71 L/100km = 21.26 km/L
Cost Per Mile Formula
Cost per mile = Gas price ($/gallon) / MPG
Examples at $3.50/gallon:
20 MPG → $0.175/mile = 17.5¢/mile
25 MPG → $0.140/mile = 14.0¢/mile
30 MPG → $0.117/mile = 11.7¢/mile
40 MPG → $0.088/mile = 8.8¢/mile
Annual cost (13,500 miles/year):
20 MPG → $2,363/year
30 MPG → $1,575/year
40 MPG → $1,181/year
Frequently Asked Questions
MPG = Miles driven ÷ Gallons used. Fill tank completely → note odometer → drive → fill again → MPG = (new odometer − starting odometer) ÷ gallons added. Example: drove 312 miles, added 11.5 gallons → 312 ÷ 11.5 = 27.1 MPG. Use our Odometer mode above — enter start/end odometer readings and gallons added.
30+ MPG is considered good for non-hybrid cars. 40+ MPG is excellent. By class: compact car 30–38; sedan 26–32; small SUV 26–34; mid-size SUV 20–26; pickup 16–22; hybrid 40–58; EV 100–130 MPGe. Average for new 2024 US vehicles is about 26–28 MPG combined. The most fuel-efficient non-hybrid sold in the US is typically 40–45 MPG.
Real-world MPG is typically 10–20% below EPA estimates because EPA tests in labs under ideal conditions. Common reasons your MPG is lower: aggressive driving (15–30% loss), highway speeds over 65 mph (7–14% per 5 mph), A/C use (5–25%), cold weather (15–24%), hilly terrain, extra weight, roof racks, and low tire pressure. The gap can be reduced with smooth, moderate-speed driving.
L/100km = 235.214 ÷ MPG. Example: 28 MPG = 235.214 ÷ 28 = 8.4 L/100km. Reverse: MPG = 235.214 ÷ L/100km. Our converter above lets you enter any unit — MPG, L/100km, or km/L — and instantly shows all three simultaneously.
New US vehicles average about 26–28 MPG combined in 2023–2024 (up from ~20 MPG in 2005 due to CAFE standards). For all vehicles on US roads including older models, the average is about 22–25 MPG. This average is rising as more hybrids are sold and fuel economy standards tighten.
Most impactful: (1) Drive 65 instead of 75 mph — saves 10–15%. (2) Smooth acceleration and coasting — saves 15–30% in city. (3) Check tire pressure monthly — correct pressure saves up to 3%. (4) Remove roof racks when not in use. (5) Regular maintenance (air filter, spark plugs, oil). (6) Combine short trips — cold engines use 20–30% more fuel per mile.
Highway typically gives 25–35% better MPG for conventional gas cars due to steady speed vs stop-and-go. Exception: hybrids get better city MPG than highway because regenerative braking recaptures energy. For example, the Toyota Prius gets 54 MPG city vs 50 MPG highway — the only mainstream car that's more efficient in city driving.
Cost per mile = Gas price ÷ MPG. Example: $3.50/gal ÷ 28 MPG = $0.125/mile = 12.5 cents/mile. For 13,500 miles/year: $1,688/year. Our calculator shows cost per mile automatically when you enter a gas price. The IRS standard mileage rate ($0.67/mile in 2024) covers fuel + maintenance + depreciation.
US MPG uses US gallons (3.785 L). UK MPG uses Imperial gallons (4.546 L) — 20% larger. So UK MPG is ~20% higher than US MPG for the same car. A 30 US MPG car ≈ 36 UK MPG. Always verify which system is used when comparing vehicles across countries. Our converter shows UK MPG alongside US MPG.
Every 2–3 fill-ups is ideal. A sudden drop of 10–15% or more from your baseline often signals a maintenance issue: dirty air filter, misfiring spark plug, low tire pressure, failing O2 sensor, or clogged fuel injector. Regular MPG tracking turns your fill-up into a simple health check for your car — catching small problems before they become expensive.