Enter the trips and the calculator multiplies each by the rate for its date. In the US the business rate was 72.5 cents until June 30 and is 76 cents from July 1, 2026, so a calculator that uses one flat number is wrong for half the year.
Employers can reimburse at the IRS rate without it counting as income, provided the employee accounts for the miles. That is why a dated log matters even when nobody is claiming a deduction.
Other countries
For the UK, switch the country box to United Kingdom: cars and vans get 55p for the first 10,000 miles of the tax year and 25p after that. For France, choose the vehicle's fiscal horsepower and Milepad applies the barème by distance band.
The result is an allowance, not advice. Your employer's policy can be lower than the official figure.