Per Diem Calculator
Total a trip’s per diem for lodging and meals, applying the standard 75% first-and-last-day rule to the meals allowance.
How it works
Nights = days − 1 · Lodging = rate × nights · M&IE = rate × (days − 2) + rate × 75% × 2 (first & last day) · Total = lodging + M&IE
A per diem reimburses travel costs at a fixed daily rate instead of actual receipts, split into a lodging component and a meals-and-incidental-expenses (M&IE) component. Federal (GSA) rules — widely mirrored by employers — pay only 75% of the M&IE rate on the first and last day of travel, since travelers are away for part of those days. Lodging is paid per night, so a five-day trip has four nights.
Worked example
A 5-day trip at $150 lodging and $79 M&IE: 4 nights of lodging = $600; M&IE is 3 full days at $79 ($237) plus two travel days at 75% ($59.25 each = $118.50), totaling $355.50. The per diem is $955.50.
Sources: U.S. GSA — Per Diem Rates
Frequently asked questions
Why is the first and last day only 75%?
Because you are typically away for only part of your departure and return days, GSA and most employers reimburse M&IE at 75% of the daily rate on those two days. Lodging is unaffected and is paid per night stayed.
Is per diem taxable?
Not if it is at or below the federal rate and you file a timely expense report. Amounts paid above the federal per diem rate, or without proper substantiation, are treated as taxable wages.
Does per diem cover lodging on the last day?
No — lodging is paid per night, and you do not stay overnight on your return day. That is why nights equal days minus one in the calculation.
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Educational payroll estimate, not tax, payroll or legal advice. Rules and rates vary by jurisdiction and employer — confirm with your payroll department.