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.

Inputs

GSA lodging rate for your destination. Default = FY2025 standard CONUS ($110); look up your city/year on gsa.gov.

GSA meals & incidental expenses rate. Default = FY2025 standard CONUS ($68); look up your city/year on gsa.gov.

Number of calendar days of travel (departure and return days count).

Result

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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&IE

Lodging is per night; M&IE is full on interior days and three-quarters on the two travel days per GSA rules.

Source: GSA — M&IE breakdown & first/last day rule

Worked examples

Example 1
5 days, $110 lodging, $68 M&IE
Inputs:
lodging=110, mie=68, days=5
Output:
4×110 + (3×68 + 2×51) = $746
Example 2
1 day trip, $68 M&IE
Inputs:
lodging=110, mie=68, days=1
Output:
0 nights + 75%×68 = $51
Example 3
3 days, $96 lodging, $59 M&IE
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.

Frequently asked

What is per diem?+
Per diem is a fixed daily allowance for business-travel expenses — lodging plus meals and incidental expenses (M&IE) — set by the GSA for federal travel and widely used by private employers. It reimburses travelers without requiring itemized receipts for covered costs.
How does the first-and-last-day meal rule work?+
GSA pays only 75% of the daily M&IE rate on the first and last days of travel, because you are traveling for only part of those days. Full days in between are reimbursed at 100% of the M&IE rate. This calculator applies that proration automatically.
How many nights of lodging does a trip have?+
One fewer than the number of travel days: a five-day trip has four nights of lodging, because you do not stay overnight after returning home on the last day. The tool computes nights as days minus one.
Why are the default rates labeled FY2025 standard CONUS?+
The "standard CONUS" rate applies to continental-US locations that do not have their own listing. It changes each fiscal year. The defaults here are the FY2025 standard figures; for an accurate result, enter the rate for your specific city and fiscal year from gsa.gov.
What counts as an incidental expense?+
Incidentals covered by M&IE include fees and tips for services (like baggage handling). They do not include items such as transportation to meals or laundry on short trips. GSA publishes the breakdown of the M&IE rate by meal and incidentals.
Are international or Alaska/Hawaii rates the same?+
No. GSA sets CONUS (continental US) rates; the Department of Defense sets rates for Alaska, Hawaii, and US territories, and the State Department sets foreign rates. Use the appropriate source and enter those numbers here.

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