Adding up a per diem trip, day by day
To add up a per diem trip, take each night’s lodging cap for the month you sleep in the area, add the full M&IE for every day between departure and return, and add 75% of the M&IE for the departure day and the return day. The trip calculator does exactly this for any area and any dates from October 1, 2025, to September 30, 2027.
Example 1: a trip across two seasons
New York City has five rate periods in FY 2027. Its cap is $358 in December and $189 in January, so a trip from Tue Dec 29, 2026 to Sat Jan 2, 2027 uses two different caps.
| Date | Lodging cap that night | M&IE | Day total |
|---|---|---|---|
| Tue Dec 29, 2026 (travel day, 75%) | $358 | $69 | $427 |
| Wed Dec 30, 2026 | $358 | $92 | $450 |
| Thu Dec 31, 2026 | $358 | $92 | $450 |
| Fri Jan 1, 2027 | $189 | $92 | $281 |
| Sat Jan 2, 2027 (travel day, 75%) | none (no night) | $69 | $69 |
Each night takes the cap of the calendar date on which it begins. The nights of December 29, 30 and 31 therefore use the December cap, and only the night of January 1 uses the January cap. The M&IE is $92 on the three full days and $69 on the two travel days. Total: $1,677.
Example 2: a trip across the fiscal year
Rates change on October 1, the first day of the federal fiscal year. A trip to Boston / Cambridge from Mon Sep 28, 2026 to Thu Oct 1, 2026 has three nights in September, under FY 2026 rates ($349 a night), and returns on October 1, the first day of FY 2027, when the cap would be $365.
| Date | Lodging cap that night | M&IE | Day total |
|---|---|---|---|
| Mon Sep 28, 2026 (travel day, 75%) | $349 | $69 | $418 |
| Tue Sep 29, 2026 | $349 | $92 | $441 |
| Wed Sep 30, 2026 | $349 | $92 | $441 |
| Thu Oct 1, 2026 (travel day, 75%) | none (no night) | $69 | $69 |
Because the return day has no night of lodging, only the M&IE of October 1 comes from the new fiscal year. Total: $1,369.
Example 3: stepping into the high season
Key West moves from $383 in January to $452 in February. A stay from Sat Jan 30, 2027 to Tue Feb 2, 2027 has two January nights and one February night:
| Date | Lodging cap that night | M&IE | Day total |
|---|---|---|---|
| Sat Jan 30, 2027 (travel day, 75%) | $383 | $64.50 | $447.50 |
| Sun Jan 31, 2027 | $383 | $86 | $469 |
| Mon Feb 1, 2027 | $452 | $86 | $538 |
| Tue Feb 2, 2027 (travel day, 75%) | none (no night) | $64.50 | $64.50 |
Total: $1,519. Shifting the same three nights one day later, to start on January 31, would put two of them in February and add $69 to the lodging part.
Example 4: anywhere at the standard rate
For a county that GSA does not list, the standard FY 2027 rate applies: $113 lodging and $68 M&IE. A two-night trip from Tue Mar 9, 2027 to Thu Mar 11, 2027:
| Date | Lodging cap that night | M&IE | Day total |
|---|---|---|---|
| Tue Mar 9, 2027 (travel day, 75%) | $113 | $51 | $164 |
| Wed Mar 10, 2027 | $113 | $68 | $181 |
| Thu Mar 11, 2027 (travel day, 75%) | none (no night) | $51 | $51 |
Total: $396, of which $226 is lodging.
The same four days in every month
Seasons decide more than the destination’s name. Running the same Monday-to-Thursday trip to New York City from the first Monday of each month of FY 2027 gives totals from $889 in January to $1,396 in October, a difference of $507 for an identical itinerary. The M&IE part is the same $322 in every month; the whole difference is lodging.
What the calculator assumes
It treats every night as spent in the chosen area, uses that area’s M&IE on both travel days, and applies the 75% rule to the first and last calendar day. It does not deduct provided meals, add lodging taxes, or handle same-day trips or stays longer than 120 nights. All of these depend on agency rules, and the result is a ceiling, not an amount anyone has approved.
Check the county first
The calculator works by GSA’s areas, and an area is a set of counties or cities. A hotel in a town that is not named on any destination page may still fall inside a listed county; if it does not, choose “Any other county” for the standard rate. Some areas reach across a state line: the Washington, DC rate also covers Arlington and Fairfax counties in Virginia and Montgomery and Prince George’s counties in Maryland. Each destination page quotes GSA’s definition beside the rates.
Trips with two stops
When a trip moves from one area to another, each night belongs to the area where you sleep. The calculator handles one area at a time, so a trip with two stops is two calculations: the first from the departure day to the day you move, the second from that day to your return. The day you move then appears in both results, once as a last day and once as a first day, so its M&IE should be counted only once; which area’s rate applies to that day is set by agency rules.
Sharing a calculation
The address bar keeps the destination and dates, for example /trip-allowance/?d=new-york-city-ny&from=2026-12-29&to=2027-01-02. Every destination page links to the calculator with its own area already chosen.
Sources: U.S. General Services Administration, per diem rate files FY 2021 to FY 2027; figures computed by Per Diem Rates. See reading the rates for how each measure is defined.