Gas Mileage for 300 miles on 2 gallons
The fuel economy for 300 miles on 2 gallons, plus projected fuel costs for common trip distances. Adjust any field below to try your own numbers.
Fuel Economy
150 MPG
1.57 L/100km
Cost Per Mile
$0.0233
Driving 300 miles on 2 gallons of fuel works out to 150 MPG (about 1.6 L/100km) — at $3.50 per gallon, that's roughly $0.02 per mile.
What is a Gas Mileage Calculator?
A gas mileage calculator measures how efficiently a vehicle uses fuel, expressed as miles per gallon (MPG) in the US or liters per 100 kilometers (L/100km) in most of the rest of the world. It's the single most direct way to track your actual real-world fuel economy — which often differs meaningfully from the EPA/manufacturer-rated MPG printed on the window sticker, since real driving conditions rarely match the standardized test cycle.
Tracking your own MPG over time is also one of the fastest ways to notice developing mechanical issues — a sudden, sustained drop in fuel economy (with no change in driving habits) is a common early sign of problems like underinflated tires, a failing oxygen sensor, or a clogged air filter.
Fuel Cost by Trip Distance at 150 MPG
Every row below is computed for your exact fuel economy and fuel price, so you can estimate the cost of an upcoming trip before you leave.
| Trip Distance | Gallons Needed | Estimated Cost |
|---|---|---|
| 25 mi | 0.17 gal | $0.58 |
| 50 mi | 0.33 gal | $1.17 |
| 100 mi | 0.67 gal | $2.33 |
| 250 mi | 1.67 gal | $5.83 |
| 500 mi | 3.33 gal | $11.67 |
| 1000 mi | 6.67 gal | $23.33 |
How Gas Mileage Is Calculated
Fill your tank completely, reset your trip odometer (or note the current mileage), and drive normally until your next fill-up. At the pump, note exactly how many gallons it takes to fill the tank back to full — that's your fuel used for the distance covered since the last fill-up.
For the metric equivalent, L/100km measures fuel used per fixed distance rather than distance per fixed fuel amount — which is why, counterintuitively, a lower L/100km number means better efficiency (the opposite direction from MPG, where higher is better).
Why Your Real MPG Differs From the Window Sticker
EPA fuel economy ratings are measured under standardized laboratory conditions — consistent temperature, a specific speed profile, and no real-world factors like wind, hills, or cargo weight. City driving with frequent stops typically returns worse MPG than the rated figure, while steady highway cruising can sometimes beat it. Cold weather is a particularly large factor: engines run less efficiently until warmed up, and gas mileage commonly drops 15–30% in freezing conditions compared to mild weather, partly due to increased engine friction and partly due to accessories like heaters and defrosters drawing engine power.
Practical Ways to Improve Gas Mileage
Aggressive acceleration and braking can lower highway fuel economy by roughly 15–30% and city fuel economy by 10–40% compared to smooth, moderate driving. Keeping tires properly inflated (a tire underinflated by just 10 PSI can cut MPG by about 3–4%), removing unnecessary roof cargo (which increases aerodynamic drag substantially at highway speeds), and reducing idle time all meaningfully improve real-world fuel economy without any change to the vehicle itself.
Example — Your Current Inputs
Driving 300 miles on 2 gallons of fuel works out to 150 MPG (about 1.6 L/100km) — at $3.50 per gallon, that's roughly $0.02 per mile.
Additional Example — A Road Trip
You're planning a 480-mile road trip in a car that gets 32 MPG, with gas priced at $3.65/gallon. You'll need about 15 gallons of fuel, costing roughly $54.75 one way. If your actual highway MPG runs a bit higher than your combined city/highway average (typical for steady interstate driving), your real trip cost will likely come in somewhat below this estimate.
About These Parameters
- Miles Driven
- The distance covered between two full tanks — reset your trip odometer at a fill-up, then read it again at the next fill-up for an accurate figure.
- Gallons Used
- The amount of fuel it took to refill the tank back to full at the end of that distance. For the most accurate reading, always fill to the same point (fully topped off) both times.
- Fuel Price
- Current price per gallon at the pump, used only to project the cost of future trips at your calculated MPG — it has no effect on the MPG figure itself.
Frequently Asked Questions
Why does my MPG vary so much between fill-ups?
A single tank's MPG is affected by the mix of city versus highway driving, temperature, wind, traffic, cargo weight, and even how full you fill the tank each time (topping off "click plus a few seconds" versus stopping exactly at the first click). For a more stable, representative figure, average your MPG across several fill-ups rather than judging fuel economy from a single tank.
Is a trip computer's MPG reading accurate?
Built-in trip computers are generally close but not perfectly accurate — they estimate fuel consumption from the engine's fuel injector timing rather than measuring the actual fuel pumped, and can drift a few percent from the true figure over time. The pump-and-odometer method used by this calculator, done consistently, is generally considered the most reliable way to verify your actual real-world MPG.
How is this different from the "Mileage Calculator"?
This Gas Mileage Calculator measures fuel efficiency (MPG) — how far your vehicle travels per gallon of fuel. The Mileage Calculator is a different tool entirely: it calculates a dollar reimbursement or tax deduction from miles driven, using a fixed per-mile rate (such as the IRS standard mileage rate), and has nothing to do with fuel consumption.
Does premium fuel improve gas mileage?
Only for engines specifically designed to require or benefit from higher octane fuel — using premium in a car designed for regular unleaded typically produces no measurable MPG improvement, since the fuel's octane rating affects knock resistance under high compression, not its energy content. Check your owner's manual; if it says "regular unleaded recommended" rather than "premium required," premium fuel is very unlikely to change your mileage at all.