Federal Per Diem Calculator
Federal travelers are reimbursed using GSA per diem rates: a daily lodging cap plus a meals and incidental expenses (M&IE) allowance set by destination. Under the Federal Travel Regulation, the first and last day of travel pay only 75 percent of the M&IE rate, full days pay 100 percent, and lodging is reimbursed for each night away (days minus one). This calculator combines your trip length with the lodging and M&IE rates you look up on GSA to estimate the total per diem reimbursement and its breakdown.
Per diem formula
Lodging nights = max(0, days - 1)
Total lodging = lodging rate * lodging nights
First/last M&IE = M&IE rate * 0.75 (applies to 2 days)
Full M&IE days = max(0, days - 2)
Total M&IE = (M&IE rate * full days) + (2 * first/last M&IE)
Total per diem = total lodging + total M&IE
If a trip is a single day, M&IE is paid at 75 percent for that day and no lodging applies. Two travel days are both treated as first/last days at 75 percent each.
Federal per diem context
- GSA sets per diem rates for the continental U.S. by city and county; many areas use the standard CONUS rate.
- The first and last calendar day of travel are reimbursed at 75 percent of the M&IE rate.
- Lodging is reimbursed at actual cost up to the nightly cap, for each night away.
- Non-foreign rates (Alaska, Hawaii, territories) come from the Department of Defense; foreign rates come from the State Department.
- The M&IE rate bundles meals plus incidentals such as tips and short local transport.
Federal per diem: frequently asked questions
What is a federal per diem?
Per diem is the daily allowance the federal government sets to reimburse employees for lodging and for meals and incidental expenses (M&IE) while traveling. The General Services Administration (GSA) publishes per diem rates for the continental U.S. by location, and the Department of Defense and State Department set rates for non-foreign and foreign areas respectively.
Why is the first and last day only 75 percent of M&IE?
Under the Federal Travel Regulation, travelers receive 75 percent of the applicable M&IE rate on the first and last day of travel, regardless of departure or return time. Full M&IE applies to each day in between. Lodging is reimbursed at the actual cost up to the daily lodging cap, and no lodging is paid for the final travel day.
How many nights of lodging are reimbursed?
Lodging is reimbursed for nights you are away, which equals the number of travel days minus one. A 3-day trip involves 2 nights of lodging. This calculator multiplies your nightly lodging cap by (days minus one) to estimate the lodging portion.
Where do I find the correct rates?
Look up the destination on the GSA per diem rate tool to find the lodging cap and the M&IE rate for the city or county. Many areas use the standard CONUS rate, while higher-cost locations have their own rates that change seasonally. Enter the lodging and M&IE figures for your destination.
Does per diem cover incidentals and tips?
Yes. The M&IE rate bundles meals plus incidental expenses such as tips to hotel staff and transportation between lodging and meal locations. The GSA publishes an M&IE breakdown showing how each daily rate splits across breakfast, lunch, dinner, and incidentals.
Official sources
- U.S. General Services Administration: Per Diem Rates.
- U.S. General Services Administration: GSA.gov.
Reviewed by the CalculatorHub team, edited by James Graham, 17 June 2026. See our methodology.