Want to know exactly what your driving costs? Just enter your distance, MPG, and gas price, and our free mileage calculator shows your fuel cost in seconds. You can also work backwards to find your real MPG from fill-up data. Perfect for commuters, road trippers, delivery drivers, and anyone tracking business mileage for taxes.
A mileage calculator is a tool that figures out how much fuel you'll use for a trip, or how efficient your car is. It's basically a math shortcut. Instead of doing all the calculations by hand, you enter:
Distance
How far you're driving (miles or km)
Fuel Economy
Your car's MPG or L/100km
Gas Price
Current price per gallon or liter
And the calculator spits out your total fuel cost. Simple, right? But you can also use it backwards. If you know how much gas you bought and how far you drove, you can figure out your car's actual MPG. That's super useful for checking if your car is running right.
You might think mileage calculators are just for road trips. But people use them for all kinds of things:
Commuters who want to know their monthly gas budget
Delivery drivers (Uber, DoorDash, pizza) tracking expenses
Small business owners calculating mileage deductions for taxes
Road trippers planning their fuel stops
Car buyers comparing fuel costs between different vehicles
Anyone trying to save money on gas
Basically, if you drive a car, this tool is for you.
Let's walk through a real example. Say you're driving from Los Angeles to San Francisco. That's about 380 miles.
Enter Your Distance: Type in 380 miles. Or if you're using kilometers, that's about 611 km. Our calculator handles both.
Enter Your Car's MPG: Let's say you drive a Honda Civic that gets 32 MPG on the highway. Don't know your car's MPG? Check the window sticker, owner's manual, or Google "[your car] MPG."
Enter the Gas Price: Right now, gas in California is around $4.50 per gallon. Enter that.
Hit Calculate: You'll use about 11.9 gallons, and it'll cost roughly $53.55.
That's it. You now know exactly how much to budget for gas on your trip.
This is super common. A lot of people have no idea what their car's actual fuel economy is. The number on the window sticker is usually optimistic. Real-world driving is different. Here's how to find your actual MPG:
Fill up your tank completely. Reset your trip odometer.
Drive normally until you need gas again.
Fill up again. Write down how many gallons you put in.
Look at your trip odometer. That's how many miles you drove.
Divide miles driven by gallons used. That's your MPG.
So if you drove 300 miles and put in 10 gallons, your MPG is 30. Easy. Our calculator can do this for you too — just use the "calculate MPG" option instead of the trip cost option.
Here's something most people don't know. That fuel economy display on your dashboard? It's usually wrong. By about 2-5 MPG.
Car manufacturers are allowed to be a little optimistic. Plus, the computer in your car is making estimates based on fuel injector pulse width and other technical stuff. It's not measuring actual fuel flow.
The only way to get real MPG is the manual method we just described. Fill up, drive, fill up, divide. That's the truth.
So if your dashboard says 32 MPG but your manual calculation says 28, trust the manual calculation. Your car is less efficient than you thought.
Your car gets different mileage in the city vs on the highway. City driving means stop-and-go traffic, idling at lights, and low speeds. Highway driving is steady cruising.
Most cars get better mileage on the highway. A typical sedan might get 25 MPG in the city and 35 MPG on the highway. That's a huge difference.
So when you're using the mileage calculator, think about what kind of driving you're doing. If you're planning a road trip, use the highway MPG number. If you're calculating your weekly commute with traffic, use the city number. Some calculators let you split the difference — if your trip is 50% city and 50% highway, average the two numbers for better accuracy.
30 miles round trip, 5 days/week = 150 miles. Car gets 25 MPG. Gas at $3.50/gallon. Weekly: 6 gallons = $21. Monthly: $84. Yearly: Over $1,000 just to get to work.
NY to LA = 2,800 miles. Toyota Camry at 34 MPG highway. Gas averages $3.80. Total: 82.4 gallons = $313. Plus about 7 gas stops — plan accordingly.
Ford F-150 at 18 MPG. 40-mile commute, gas at $4.00. Daily: 2.2 gallons = $8.80. Weekly: $44. Monthly: $176. Yearly: Over $2,100 just for commuting.
See the difference? A fuel-efficient car can save you thousands per year compared to a truck or SUV.
Once you know your MPG, you might want to improve it. Here are the things that actually work:
Check your tire pressure. Under-inflated tires create more rolling resistance. You can lose 1-2 MPG just from low tires.
Remove roof racks and cargo boxes. They create drag. At highway speeds, a roof rack can cost you 5-10 MPG.
Don't drive like a maniac. Hard acceleration and hard braking kill your mileage. Smooth driving saves gas.
Slow down. Every 5 mph over 60 mph is like paying an extra $0.20 per gallon. At 75 mph, you're burning way more fuel.
Use cruise control. On the highway, cruise control maintains a steady speed, which saves gas.
Reduce idling. Idling gets 0 MPG. If you're waiting more than a minute, turn off the engine.
Keep up with maintenance. Dirty air filters, old spark plugs, and bad oxygen sensors all hurt mileage.
These tips can add up. You might gain 5-10 MPG just by changing your driving habits and keeping your car maintained.
If you drive for work — deliveries, sales calls, Uber, whatever — you can deduct your mileage on your taxes. This is a big deal.
For 2024, the IRS mileage rate is 67 cents per mile. That means for every mile you drive for business, you can deduct $0.67 from your taxable income. So if you drive 10,000 miles for work in a year, that's a $6,700 deduction. That could save you over $1,500 in taxes depending on your tax bracket.
But you need to track your mileage. The IRS requires documentation. You can't just guess.
What to record for each trip:
You can use a notebook, a spreadsheet, or a mileage tracking app. Just make sure you're consistent. Our mileage calculator can help you figure out your total deduction — just multiply your business miles by the IRS rate.
Mistake 1: Using the Wrong MPG Number
If you're doing a highway trip, use highway MPG. If you're doing city driving, use city MPG. Mixing them up gives you a wrong answer.
Mistake 2: Forgetting That Gas Prices Vary
Gas costs different amounts in different places. California is expensive. Texas is cheap. For long trips, use an average price for the areas you'll drive through.
Mistake 3: Not Accounting for Traffic
If driving through a city during rush hour, your MPG will be terrible. Plan for that. Add 20-30% to your fuel estimate for heavy traffic.
Mistake 4: Thinking the Dashboard Is Accurate
Your car's computer is optimistic. Calculate manually to get the real number.
Mistake 5: Ignoring Your Car's Condition
An old car with worn-out parts will get worse mileage. If your car needs a tune-up, your MPG will be lower than expected.
Here's something interesting. The most fuel-efficient car ever made was the 1994 Honda Insight. It got 70 MPG on the highway. That's better than most modern hybrids.
And the worst? The 1970s Cadillac Eldorado got about 8 MPG. Imagine filling that up today.
Also, did you know that driving with your windows down at highway speeds actually hurts your mileage more than using the AC? The drag from open windows creates more resistance than the AC compressor. So on the highway, roll up the windows and use the AC.
One more thing. The most efficient speed for most cars is between 50 and 60 mph. Above that, wind resistance increases exponentially. At 80 mph, you're burning about 25% more fuel than at 60 mph.
These terms get used interchangeably, but there's a slight difference.
A mileage calculator usually focuses on distance and fuel economy. It tells you how many miles per gallon you're getting.
A fuel cost calculator takes it a step further and tells you how much money you'll spend.
Our calculator does both. So you don't need to choose. Just pick what you want to calculate.
Want your calculations to be spot-on? Follow these rules:
Use the same gas station and pump every time for consistency
Fill up until the pump clicks — don't top off
Record your miles immediately after filling up
Track over multiple tanks for a reliable average
Use real-world MPG, not the window sticker number
Fill up completely, reset your trip odometer. Drive normally, then refill. Divide miles driven by gallons used. For example, 300 miles ÷ 10 gallons = 30 MPG. Our calculator does this instantly.
City MPG is measured in stop-and-go traffic. Highway MPG is at steady speeds. Highway is typically 5-10 MPG higher because there's no idling or constant acceleration. Combined MPG averages both.
Dashboard displays are estimates — often 2-5 MPG optimistic. They use fuel injector data, not actual fuel flow. Manual calculation (miles ÷ gallons) is the only accurate method.
Divide gas price by your MPG. At $3.50/gallon and 25 MPG, that's $0.14 per mile. A 100-mile trip costs about $14 in gas. Use our calculator for exact numbers.
Check tire pressure, remove roof racks, drive smoothly, slow down (every 5 mph over 60 costs extra), use cruise control, reduce idling, and keep up with maintenance. You can gain 5-10 MPG.
The 2024 IRS rate is 67 cents per mile for business driving. You can deduct this from your taxable income. 10,000 business miles = $6,700 deduction. You must keep accurate records of each trip.
At highway speeds, use AC — open windows create drag that hurts MPG more. Around town, roll down windows — AC uses extra fuel and drag is minimal at low speeds.
Divide total miles by highway MPG to get gallons needed. Multiply by average gas price along your route. For a 2,800-mile trip at 34 MPG with $3.80 gas: about 82 gallons = $313. Add 10-15% for traffic and detours.
Between 50-60 mph for most cars. Above 60, wind resistance increases exponentially. At 80 mph, you burn about 25% more fuel than at 60 mph.
Record date, start/end locations, purpose, and miles for every business trip. Use a notebook, spreadsheet, or mileage app. The IRS requires documentation — estimates aren't accepted.
Winter-blend gas has less energy. Engines take longer to warm up. Cold air is denser (more drag). Winter tires have more rolling resistance. A 10-20% winter drop is normal.
The 1994 Honda Insight got 70 MPG highway — better than most modern hybrids. Today, the Toyota Prius leads at about 57 MPG combined. Electric vehicles are even cheaper per mile to operate.
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