This calculator works out exactly how much you are paying for every mile you drive, whether that is one trip, a work vehicle, or a whole fleet. Enter the total cost, covering fuel, tolls, parking or any other expenses you want counted, then enter the distance travelled in miles. Choose your currency symbol, and if you want a fuller running cost, add annual fixed costs such as insurance, registration and depreciation alongside your annual mileage so they blend into the per-mile figure. The results show your cost per mile, the equivalent cost per kilometre using the exact 1.60934 km conversion, your total cost for the trip, and a cost per 100 miles figure. Select or enter an annual mileage projection and the calculator also breaks down what that rate means over a year, showing projected annual cost plus monthly, weekly and daily estimates, so you see the bigger picture rather than just one trip. This suits claiming mileage reimbursement from an employer, comparing running costs between vehicles, budgeting for a fleet, or checking a quoted rate against your own figures. Because it converts between miles and kilometres automatically, it also helps New Zealand drivers compare a rate quoted in miles against local kilometre rates. Figures are indicative only; your actual cost per mile depends on which expenses you include and how accurately you record distance.
The cost per mile formula is straightforward:
Cost per mile = Total cost / Total miles
For example, if you spent $45 on fuel and tolls for a 150-mile trip, your cost per mile is $45 / 150 = $0.30 per mile. To convert this to cost per kilometre, divide by 1.60934 (the number of kilometres in a mile): $0.30 / 1.60934 = $0.186 per km.
The right costs to include depend on your purpose:
| Purpose | Costs to include |
|---|---|
| Single trip | Fuel, tolls, parking, ferry fares |
| Business mileage reimbursement | Fuel only, or use a standard rate (e.g. IRD rate in NZ, IRS rate in the US) |
| Full vehicle running cost | Fuel, servicing, tyres, registration, insurance, depreciation |
| Fleet management | All vehicle costs divided by total fleet miles |
Miles are used in the United States, United Kingdom, and a few other countries. Most of the world uses kilometres. The conversion is:
For example, $0.50 per mile equals $0.50 / 1.60934 = $0.311 per km. If you are a New Zealand driver and need to convert a mileage rate to kilometres, this calculator handles that automatically.
Many employers and tax authorities publish standard mileage rates to simplify reimbursement. These rates are designed to cover the average cost per mile including fuel, wear and tear, and other expenses. In New Zealand, Inland Revenue (IRD) publishes kilometre rates for business use of private vehicles. In the United States, the IRS publishes a cents-per-mile rate annually. Always check the current rate for your jurisdiction, as these rates change each year.
With the default values:
Cost per mile = $45.00 / 150 = $0.30 per mile
Distance in km = 150 x 1.60934 = 241.40 km
Cost per km = $45.00 / 241.40 = $0.186 per km
Cost per 100 miles = $0.30 x 100 = $30.00
Sources and method: Cost per mile formula: total cost divided by total miles travelled. Mile-to-kilometre conversion factor: 1 mile = 1.60934 km (exact international definition). IRD kilometre rates: ird.govt.nz/topics/income-tax/business-income-tax/kilometre-rates.
This calculator provides indicative estimates only. Actual costs vary depending on vehicle type, fuel prices, driving conditions, and included cost categories. For tax reimbursement purposes, check current IRD kilometre rates or the applicable rate for your country.
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