Methodology
Methodology and checks
How the data is built
- Each GSA master file (FY2015–FY2027) is read row by row. Season begin and end dates are expanded to every day of the fiscal year, and the build stops if any day is covered by no season or by two.
- Monthly lodging is the highest daily rate in each month, which is how GSA's ZIP code file and API show it. The calculator uses the daily season dates.
- Destinations are matched across years by state and name. A renamed area therefore starts a new history; pages say so where a county moved.
- The current fiscal year is the latest one whose October 1 has passed; a file published ahead of October 1 is shown as upcoming.
- Foreign rates are read from the State Department lookup; Alaska, Hawaii and territory rates from the DTMO file.
Automatic cross-checks
- FY2026: 40,426 ZIP codes; 6 rows where the ZIP file's monthly lodging or M&IE differs from the master file or cannot be matched
- FY2027: 40,426 ZIP codes; 0 rows where the ZIP file's monthly lodging or M&IE differs from the master file or cannot be matched
- Foreign rates: 1079 of 1081 rows present in both the State Department lookup and the DTMO file agree on lodging and M&IE; differences are usually a newer effective date in one of the two sources.
Spot-check against official lookups
Spot-check run 2026-10-22: 14 of 14 rates read from the built pages match the official source (GSA per diem API with the public demo key, the State Department lookup, or the DTMO file).
| Rate | This site | Official | Result |
|---|---|---|---|
| Gulf Shores, AL FY2027: 12 monthly lodging caps + M&IE (GSA API: Gulf Shores) | $144–$221 / $74 | $144–$221 / $74 | Match |
| San Francisco, CA FY2027: 12 monthly lodging caps + M&IE (GSA API: San Francisco) | $232–$325 / $92 | $232–$325 / $92 | Match |
| New York City, NY FY2027: 12 monthly lodging caps + M&IE (GSA API: New York City) | $189–$358 / $92 | $189–$358 / $92 | Match |
| Park City, UT FY2027: 12 monthly lodging caps + M&IE (GSA API: Park City) | $227–$499 / $92 | $227–$499 / $92 | Match |
| Washington, DC FY2027: 12 monthly lodging caps + M&IE (GSA API: District of Columbia) | $192–$295 / $92 | $192–$295 / $92 | Match |
| Boston, MA FY2027: 12 monthly lodging caps + M&IE (GSA API: Boston / Cambridge) | $213–$365 / $92 | $213–$365 / $92 | Match |
| Key West, FL FY2027: 12 monthly lodging caps + M&IE (GSA API: Key West) | $267–$452 / $86 | $267–$452 / $86 | Match |
| Aspen, CO FY2027: 12 monthly lodging caps + M&IE (GSA API: Aspen) | $173–$419 / $92 | $173–$419 / $92 | Match |
| Austin, TX FY2027: 12 monthly lodging caps + M&IE (GSA API: Austin) | $184–$184 / $80 | $184–$184 / $80 | Match |
| Sydney, Australia: lodging + M&IE, all seasons (DTMO OCONUS file) | $280 + $147 | $280 + $147 | Match |
| Tokyo City, Japan: lodging + M&IE, all seasons (DTMO OCONUS file) | $346 + $122 | $346 + $122 | Match |
| London, United Kingdom: lodging + M&IE, all seasons (DTMO OCONUS file) | $424 + $174 | $424 + $174 | Match |
| Honolulu, Hawaii: lodging + M&IE, all seasons (DTMO OCONUS file) | $202 + $163 | $202 + $163 | Match |
| Juneau, Alaska: lodging + M&IE, all seasons (DTMO OCONUS file) | $239 + $143; $274 + $143 | $239 + $143; $274 + $143 | Match |
Source: U.S. General Services Administration (GSA), per diem rates and per diem files. Not affiliated with GSA. All sources