The basic formula for mileage calculation

To calculate mileage, subtract your starting odometer reading from your ending odometer reading. That difference is the number of miles you drove. If your odometer read 45,230 miles when you left and 45,287 miles when you arrived, you drove 57 miles.

The math works the same whether you are tracking a single trip or a full year of driving. Keep a record of the date, starting mileage, ending mileage, and the purpose of the trip. For tax purposes, the IRS requires this documentation — a mileage log or contemporaneous written record — before you can claim any deduction.

If you do not have an odometer reading for a particular trip, you can estimate using a mapping tool like Google Maps or MapQuest. Enter your starting address and destination, and the tool will show the distance. This is less reliable than an odometer, but it is better than guessing if your records are incomplete.

Key Takeaways

  • Mileage is calculated by subtracting your starting odometer reading from your ending reading, and you need this number to claim tax deductions or request reimbursement.
  • The IRS requires a written record of the date, starting mileage, ending mileage, and trip purpose — a mileage log is the standard format.
  • Mapping tools can estimate distance if you do not have odometer readings, but actual odometer records are what tax authorities and employers prefer.
  • Mileage rates change yearly for tax deductions, so you must know the rate that applied during the year you drove, not the current year's rate.

Tracking mileage throughout the year

A mileage log does not need to be complicated. A straightforward notebook, a spreadsheet, or a dedicated app all work. The IRS requires four pieces of information for each trip: the date, the starting odometer reading, the ending odometer reading (or total miles), and the business purpose of the trip.

Write down the odometer reading before you leave and when you arrive. Do this when ready — waiting until the end of the week to reconstruct trips from memory is not considered a contemporaneous record by the IRS. If you forget to write it down on the day of the trip, you cannot go back and add it later and claim it is valid.

Many people use a mileage app on their phone, which automatically logs the distance between two locations and timestamps the entry. Apps like MileIQ, Stride Health, or TripLog can sync with your phone's location services. If you prefer paper, a small notebook in your car works just as well — the format does not matter, only that the record exists and is dated.

Converting mileage to a dollar amount for taxes

Once you have your total mileage, you convert it to a deduction using the IRS standard mileage rate. This rate changes each year. For 2024, the rate for business driving is 67 cents per mile. For medical or charitable driving, it is 21 cents per mile. For moving expenses (if you are a member of the military), it is 21 cents per mile.

To find the rate that applies to your situation, visit the IRS website or ask your tax preparer. The rate you use must match the year in which you drove, not the year you file your taxes. If you drove 5,000 business miles in 2023, you use the 2023 rate (65.5 cents per mile), not the 2024 rate, even if you file your 2023 return in 2024.

Multiply your total mileage by the rate: 5,000 miles × $0.655 = $3,275. That $3,275 is the deduction you can claim on your tax return, assuming you meet all other requirements for the type of driving you did.

Mileage reimbursement from an employer

If your employer reimburses mileage, the process is similar but the rate may be different. Many employers use the IRS standard rate, but some set their own. Check your employee handbook or ask your manager what rate your company uses.

Submit your mileage log to your employer's accounting or finance department, usually through an expense report form or online portal. Include the same information you would for a tax deduction: dates, starting and ending mileage, and trip purpose. Some employers require receipts or additional documentation; ask before you submit.

The employer will multiply your total mileage by their reimbursement rate and issue a check or direct deposit. This is separate from your tax deduction — you cannot claim a mileage deduction on your taxes for miles your employer already reimbursed you for.

Common mistakes in mileage calculation

The most common error is including commute miles. Driving from your home to your regular workplace and back is not deductible, even if you work from multiple locations. Only miles driven for business purposes beyond your normal commute count. If you work from home and drive to a client meeting, those miles count. If you drive from home to your office, they do not.

Another mistake is rounding. Write down the actual odometer reading, not a rounded number. If your odometer reads 45,287.3 miles, record 45,287.3, not 45,290. Small rounding errors add up across hundreds of trips.

A third error is forgetting to record the trip purpose. "Drove 50 miles" is not enough. "Drove 50 miles to client meeting in Springfield" is what the IRS needs. The purpose shows why the trip was business-related, not personal.

Using mapping tools when you do not have odometer readings

If you forgot to record your odometer reading but you remember where you went, open Google Maps or MapQuest and enter your starting address and destination. The tool will show the distance in miles. Round to the nearest tenth of a mile.

This method is less reliable than an odometer reading because it assumes you took the most direct route and did not make detours. If you took a longer route due to traffic or a stop along the way, the mapping tool will underestimate your actual mileage. Use this only when you have no other option, and note in your log that the distance is estimated rather than recorded.

The IRS prefers actual odometer records over estimates, so if you are audited and your log contains many estimated distances, you may need to explain why. Keeping accurate odometer readings from the start is always the safer approach.

Mileage calculation for multiple vehicles

If you drive more than one vehicle for business, keep a separate mileage log for each. Record the vehicle make and model or license plate number so you can tell them apart. At the end of the year, add up the miles for each vehicle separately, then add all vehicles together for your total business mileage.

Some people use a single spreadsheet with a column for vehicle name or ID. Others keep separate notebooks. The format does not matter — what matters is that you can show which miles were driven in which vehicle, in case you need to prove it later.

If you lease or finance a vehicle, the mileage log also helps you track wear and tear for maintenance records or lease-end inspections. Recording mileage is useful for more than just taxes.

Frequently Asked Questions

Do I have to use an app to track mileage, or can I use a notebook?

A notebook works fine. The IRS does not require a specific format or tool. What matters is that you record the date, starting mileage, ending mileage, and trip purpose on the day you drive, not later. An app can be more convenient because it timestamps entries automatically, but a handwritten log is equally valid if you fill it out right away.

What if I drove for both business and personal reasons on the same trip?

Only the business portion counts. If you drove 20 miles to a client meeting and then 10 miles to run a personal errand, record 20 miles, not 30. If the trip is mixed and you cannot separate the distances, record only the miles driven for business purposes. When in doubt, be conservative — the IRS will disallow mileage you cannot clearly justify.

Can I claim mileage for driving to a job interview?

No. Mileage to a job interview is considered personal, not business, even if you are currently employed elsewhere. The exception is if you are already in that line of work and the interview is for a similar position with a different employer — then it may count as business mileage. Ask a tax professional if you are unsure.

What happens if I do not have a mileage log when I file my taxes?

Without a contemporaneous written record, the IRS will not allow you to claim a mileage deduction. You can claim actual expenses (gas, maintenance, insurance) instead, but you will need receipts for those. A mileage deduction is usually simpler and larger, so keeping a log as you drive is worth the effort.

Does the mileage rate include gas, insurance, and maintenance?

Yes. The IRS standard mileage rate is designed to cover all vehicle operating costs: gas, oil, tires, maintenance, insurance, and depreciation. You do not add these costs separately when you use the mileage rate. If you claim the mileage deduction, you cannot also deduct gas receipts or maintenance bills for those same miles.