Calculate Mpg

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Miles Per Gallon (MPG) –

Fuel Cost Per Mile –

Total Trip Cost –

Distance Driven –

How to Calculate Your Vehicle's MPG

Understanding your car's fuel efficiency is one of the most effective ways to manage travel costs and monitor vehicle health. MPG, or Miles Per Gallon, represents the distance a vehicle can travel on a single gallon of fuel.

The MPG Formula

The math behind fuel efficiency is straightforward:

MPG = Total Miles Driven ÷ Gallons of Fuel Used

Step-by-Step Instructions

1. Fill your tank: Go to the gas station and fill your tank completely. Reset your trip odometer to zero or record your current master odometer reading.
2. Drive normally: Use your vehicle as you normally would until the tank is low (usually around a quarter tank).
3. Refill and record: Fill the tank completely again. Note exactly how many gallons it took to fill the tank (from the receipt) and record your new odometer reading or the value on your trip odometer.
4. Calculate: Divide the miles you drove by the gallons you just pumped.

MPG Calculation Example

Let's say your starting odometer was 50,000 miles. You drove until the odometer read 50,320 miles. When you refilled, you pumped 10 gallons of fuel.

• Distance: 50,320 – 50,000 = 320 miles
• Fuel: 10 gallons
• Calculation: 320 / 10 = 32 MPG

Why is My MPG Lower Than the EPA Rating?

The EPA ratings on your car's window sticker are generated under controlled laboratory conditions. Real-world MPG is influenced by several factors:

• Driving Habits: Rapid acceleration and heavy braking significantly reduce efficiency.
• Idling: If you spend a lot of time in traffic or warming up your car, you are getting 0 MPG during that time.
• Tire Pressure: Under-inflated tires increase rolling resistance, making the engine work harder.
• Vehicle Load: Carrying heavy cargo or using roof racks creates aerodynamic drag and adds weight.
• Air Conditioning: Running the AC in stop-and-go traffic can decrease efficiency by up to 20%.

function calculateMPG() { var calcType = document.querySelector('input[name="calcType"]:checked').value; var miles = 0; var gallons = parseFloat(document.getElementById('gallonsUsed').value); var price = parseFloat(document.getElementById('pricePerGallon').value); if (calcType === 'total') { miles = parseFloat(document.getElementById('totalMiles').value); } else { var start = parseFloat(document.getElementById('startOdo').value); var end = parseFloat(document.getElementById('endOdo').value); if (!isNaN(start) && !isNaN(end)) { miles = end – start; } } if (isNaN(miles) || isNaN(gallons) || miles <= 0 || gallons 0) { totalCost = gallons * price; costPerMile = totalCost / miles; document.getElementById('resTotalCost').innerText = "$" + totalCost.toFixed(2); document.getElementById('resCostPerMile').innerText = "$" + costPerMile.toFixed(3); } else { document.getElementById('resTotalCost').innerText = "N/A"; document.getElementById('resCostPerMile').innerText = "N/A"; } // Smooth scroll to results document.getElementById('mpgResultArea').scrollIntoView({ behavior: 'smooth', block: 'nearest' }); }