Per-Diem Calculator (US GSA Rules)
Compute a US business-travel per diem from the lodging and M&IE rates, applying the GSA 75% first-and-last-day meal rule.
Result
- Nights of lodging4
- Lodging total$440.00 (4 × $110.00)
- M&IE — travel days (75%)2 × $51.00 = $102.00
- M&IE — full days3 × $68.00 = $204.00
- M&IE total$306.00
- Grand total$746.00
Step-by-step
- Lodging is paid per night: 5 days = 4 nights × $110.00 = $440.00.
- M&IE: first and last travel days at 75% ($51.00 each), 3 full days at $68.00.
- M&IE total $306.00 + lodging $440.00 = $746.00.
How to use this calculator
- Look up your destination's GSA lodging and M&IE rates for the correct fiscal year on gsa.gov.
- Enter those rates (the defaults are the FY2025 standard CONUS figures).
- Enter the total number of travel days, counting departure and return days.
- Read the total per diem with the lodging and meal breakdown.
About this calculator
US federal per diem reimburses business travelers a fixed daily amount for lodging and for meals and incidental expenses (M&IE), at rates set each fiscal year by the General Services Administration (GSA). This calculator applies GSA's proration rules to a trip: lodging is reimbursed per night (so a five-day trip has four nights), and M&IE is paid at the full daily rate for each full day on travel but only 75% of the rate on the first and last days, since you are traveling for part of those days. Enter the GSA lodging and M&IE rates for your destination — the tool defaults to the FY2025 standard CONUS rates that apply to locations without a specific listing, but most cities have their own higher rates and the figures change annually, so look yours up on gsa.gov for the correct year. The result breaks out lodging, prorated travel-day meals, and full-day meals.
How it works — the formula
Lodging total = rate × (days − 1) nights
M&IE total = (days − 2) × rate + 2 × 75% × rate [days ≥ 2]
= 75% × rate [days = 1]
Total = Lodging + M&IELodging is per night; M&IE is full on interior days and three-quarters on the two travel days per GSA rules.
Worked examples
- Inputs:
- lodging=110, mie=68, days=5
- Output:
- 4×110 + (3×68 + 2×51) = $746
- Inputs:
- lodging=110, mie=68, days=1
- Output:
- 0 nights + 75%×68 = $51
- Inputs:
- lodging=96, mie=59, days=3
- Output:
- 2×96 + (1×59 + 2×44.25) = $339.50
Limitations
- Default rates are FY2025 standard CONUS — look up your city/year on GSA.
- CONUS only; Alaska/Hawaii/foreign rates come from other agencies.
- Does not handle partial reimbursements, conference lodging caps, or provided meals.
Applies GSA proration rules; confirm exact current-year rates on gsa.gov for reimbursement.