Mileage Calculator

It's simpler than most people expect. You only need two numbers: how far you drove and how much fuel you used.

Here's how to do it:

1. Fill your tank all the way and write down the current odometer reading.
2. Drive normally until you need to fill up again.
3. Fill the tank, then note the new odometer reading and how many gallons it took.
4. Subtract your starting odometer number from the new one to get miles driven.
5. Divide that by the gallons used.

That result is your miles per gallon. It's a snapshot of how efficiently your car used fuel over that stretch. One tank can be skewed by an unusual amount of highway miles or heavy city traffic, so do it a few times and average the results if you want something more reliable.

The core formula is short:

MPG = Miles Driven ÷ Gallons Used

Drove 350 miles and used 12 gallons? Your mileage is:

350 ÷ 12 = 29.17 MPG

You can rearrange it depending on what you're actually trying to figure out:

• Gallons needed for a trip: Miles ÷ MPG
• How far you can go: MPG × Gallons in tank
• Fuel cost for a trip: (Miles ÷ MPG) × Price per gallon

Those three cover most of the questions drivers actually ask. Once you're comfortable with the base formula, the rest is just swapping in different numbers.

MPG stands for miles per gallon. It's the standard measure of fuel economy in the United States, and the concept is simple: higher MPG means your car goes further on each gallon, which saves you money.

To calculate it, you need two things:

• Miles driven (from your odometer)
• Gallons used (from your fill-up receipt)

Divide miles by gallons and you're done. Now, the MPG estimate on a car's window sticker comes from EPA testing under controlled conditions. Real-world numbers are often different. Your driving habits, the roads you're on, even the weather all push that number around.

As a rough benchmark: compact cars often hit 30 to 40 MPG on the highway, while trucks and larger SUVs tend to land somewhere between 15 and 25. Hybrids and EVs measure things a bit differently, but the underlying idea is the same.

MPG tells you how far you go per gallon. A fuel consumption calculator flips that around: how many gallons does it actually take to cover a given distance? That framing is more useful when you're budgeting for a trip.

Gallons Needed = Miles ÷ MPG

Driving 450 miles in a car that gets 28 MPG:

450 ÷ 28 = 16.07 gallons

From there, multiply by the current gas price and you've got your fuel cost. One thing worth knowing: many countries use liters per 100 kilometers (L/100km) instead of MPG. Lower L/100km is better, since it means the car needs less fuel to travel the same distance. That's the opposite logic from MPG, which confuses people when they're comparing vehicles across different markets.

This is probably the most practical one for most drivers. Before a long drive or road trip, knowing what you'll spend on fuel helps you plan your budget and decide whether driving even makes sense.

The formula pulls everything together:

Fuel Cost = (Distance ÷ MPG) × Gas Price

Quick example: 600-mile drive, car gets 30 MPG, gas is $3.50 per gallon.

• Gallons needed: 600 ÷ 30 = 20 gallons
• Total fuel cost: 20 × $3.50 = $70.00

Change one variable and the cost shifts fast. A car getting 25 MPG on that same trip costs $84 instead of $70. That's a $14 difference on a single trip, and it adds up quickly if you're driving long distances regularly.

Fuel efficiency and fuel economy get used interchangeably a lot, but efficiency is the bigger concept. It's really about how well your engine converts fuel into motion. A fuel efficiency calculator helps you put a number on that and track it over time.

One useful habit: log multiple fill-ups instead of relying on a single calculation. If your MPG drops noticeably over several tanks in a row, that's worth investigating. Underinflated tires, a clogged air filter, and overdue tune-ups are common causes.

Some drivers prefer tracking cost per mile rather than MPG. It gives you a dollar figure instead of a ratio, which is easier to work with when budgeting. More on that in the fuel cost per mile section below.

If you're shopping for a car from another country or comparing international vehicle specs, you'll run into both MPG and km/L. They measure the same thing in different units.

To convert MPG to km/L, multiply by 0.425. Going the other way, multiply km/L by 2.352. L/100km works a little differently since it measures consumption rather than efficiency, so you divide 235.21 by the MPG value instead.

Sometimes worked examples are the fastest way to make a formula click. Here are four common scenarios:

Example 1: Basic MPG
You drove 320 miles and used 10.5 gallons.
320 ÷ 10.5 = 30.5 MPG

Example 2: Fuel needed for a trip
Driving 500 miles, truck gets 22 MPG.
500 ÷ 22 = 22.7 gallons needed

Example 3: Trip fuel cost
Same 500-mile trip, gas at $3.80/gallon.
22.7 × $3.80 = $86.26 in fuel

Example 4: Range on a full tank
14-gallon tank, 32 MPG.
14 × 32 = 448 miles of range

Those four cover most of what drivers actually want to know. Just plug in what you have and solve for whatever's missing.

Fuel is one of the bigger variable costs on any road trip, and it's easy to underestimate. A quick calculation before you leave can save you from a nasty surprise at the pump.

Simple approach:

1. Get the total distance of your route from Google Maps or your GPS.
2. Know your vehicle's average MPG, either from your dashboard display or a few recent fill-up calculations.
3. Look up average gas prices for the states you'll be passing through.
4. Run the formula: (Total Miles ÷ MPG) × Gas Price = Estimated Fuel Cost

Gas prices can vary by 30 to 50 cents per gallon or more across state lines. Checking something like GasBuddy before you leave lets you plan where to fill up along the way. Topping off in a cheaper state right before crossing into an expensive one is a small but real way to save.

Also worth knowing: mostly highway driving usually gets you better MPG than your combined EPA estimate, so your actual fuel cost might come in a bit lower than expected on a long interstate run.

EPA ratings come from controlled testing. Real driving is a lot messier, and plenty of everyday things drag fuel efficiency down.

• Tire pressure: Underinflated tires increase rolling resistance. Being just 5 PSI low can cut MPG by 1 to 2 percent.
• Driving speed: Fuel economy usually peaks around 50 to 60 mph. Above that, aerodynamic drag climbs fast. Going 80 mph instead of 65 can knock 15 to 20 percent off your MPG.
• Air conditioning: AC puts extra load on the engine, especially in stop-and-go traffic. At highway speeds it's often more efficient than open windows, which create drag.
• Cargo weight: Every extra 100 pounds costs about 1 percent in fuel economy. A fully loaded truck bed or SUV adds up on long hauls.
• Cold weather: Cold engines burn more fuel, and winter-blend gasoline has slightly less energy in it. Lower MPG in winter is normal.
• Aggressive driving: Hard acceleration and heavy braking hit fuel economy harder than almost anything else. Smooth, anticipatory driving can improve MPG by 10 to 40 percent depending on conditions.
• Maintenance: A dirty air filter, worn spark plugs, or failing oxygen sensors all drag efficiency down. Keeping up with scheduled maintenance genuinely pays off in fuel savings over time.

Putting MPG numbers side by side helps make sense of the differences between vehicle types. Here's a general look at what to expect:

These are general ranges, not guarantees. Your actual numbers depend on how and where you drive. But the table is useful when you're weighing vehicle options, or just trying to understand why filling up your truck costs so much more than filling up your partner's compact car.

MPG is handy for comparing vehicles, but fuel cost per mile is the number that tells you what you're actually spending every time you drive. It translates efficiency into dollars.

Cost Per Mile = Gas Price ÷ MPG

Gas at $3.60 per gallon, car gets 30 MPG:

$3.60 ÷ 30 = $0.12 per mile

So every mile costs you 12 cents in fuel. Drive 15,000 miles a year and that's roughly $1,800 in gas. If prices climb to $4.50 per gallon, that becomes $2,250. Drop your MPG to 20 and you're at 22.5 cents per mile, which works out to $3,375 a year at that same mileage.

This metric also comes up for reimbursement. The IRS standard mileage rate covers fuel plus depreciation and maintenance, but knowing your actual fuel cost per mile helps you see how much of that rate is going purely to gas.

Quick reference for converting between common fuel economy and distance units:

For distance, 1 mile equals 1.609 kilometers. To convert miles to kilometers, multiply by 1.609. To go the other way, divide by 1.609. These conversions come up most when you're looking at specs from international manufacturers or planning a trip across the Canadian or Mexican border.