Per Diem Calculator

Frequently Asked Questions

How is per diem calculated?

Lodging is reimbursed per night up to the rate cap; meals & incidentals (M&IE) are paid per day, but the first and last travel days are typically only 75% of the M&IE rate.

Why are travel days only 75%?

GSA-style rules assume partial-day travel on departure and return, so M&IE is reduced to 75% on those two days regardless of actual hours.

Do provided meals reduce per diem?

Yes - if a conference or hotel provides a meal, that meal's portion is deducted from the day's M&IE. The calculator lets you subtract provided meals.

Are these the official rates?

No - enter your locality's current rate. GSA, DoD, and State Department rates change yearly and by city; this is an estimate, verify the official table.

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Estimates for informational purposes only.

Important Disclaimer: Estimates for informational purposes only.

This calculator provides estimates for informational purposes only. Results are based on assumptions and may not reflect actual outcomes. Consult qualified professionals in relevant fields before making important decisions based on these results.

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How This Calculator Works

U.S. federal per diem reimbursement has two independent buckets. Lodging is paid per night of stay at the location's nightly cap: Lodging Rate × Nights. Meals & Incidental Expenses (M&IE) is paid per calendar day, but the first and last days of travel are reimbursed at only 75% of the daily M&IE rate under the GSA standard. This tool computes Lodging Total + (Full Days × M&IE) + (Travel Days × M&IE × 0.75) − any employer-provided meal deductions. Rates vary by destination and fiscal year - always verify the current figure on the official GSA per diem lookup before filing.

Worked Example

Suppose you travel to a city with a $107 lodging cap and a $68 M&IE rate for a 3-night trip: 2 full days on site plus 2 travel days (departure and return). Lodging is $107 × 3 = $321. Full-day M&IE is 2 × $68 = $136. The two travel days pay 2 × $68 × 0.75 = $102. With no provided meals, total reimbursement is $321 + $136 + $102 = $559. If a conference supplied one lunch (a $20 deduction in this example), M&IE drops accordingly and the total falls to $539. Now scale it up: a 5-night high-cost-city assignment at a $258 lodging cap and a $79 M&IE with 4 full days and 2 travel days runs $258 × 5 = $1,290 lodging, plus 4 × $79 = $316 and 2 × $79 × 0.75 = $118.50 in meals - $1,724.50 before any provided-meal deduction. The lodging bucket dominates long trips, which is why nightly-cap accuracy matters most.

Real-World Use

Federal employees, government contractors, and many private firms that mirror GSA policy use per diem to avoid line-by-line expense reports - you keep the allowance whether or not you spend it all, subject to employer rules, so a frugal traveler effectively earns the unspent M&IE. Travelers use this estimate to budget a trip, decide whether booking a $90 hotel under a $107 cap lets them pocket the difference (it usually does not - lodging is typically reimbursed at actual cost up to the cap, not the full cap), and to sanity-check a finance department's reimbursement before signing the voucher. Contractors negotiating travel clauses use it to scope reimbursable trip costs in a statement of work, and managers use it to forecast a team's conference travel budget across a fiscal quarter.

Common Mistakes

Paying full M&IE on travel days. The first and last days are always 75% under GSA rules, regardless of departure or return time.

Confusing nights with days. Lodging is per night; M&IE is per calendar day. A 2-night trip spans 3 M&IE days.

Forgetting provided-meal deductions. A free conference breakfast or hosted dinner must be subtracted from M&IE.

Using a stale rate. GSA updates rates every federal fiscal year (October 1); high-cost cities have their own tables.

Limitations & Related Tools

This is an estimate, not an official GSA computation. It does not handle non-standard partial-day proration used by some non-federal employers, foreign or non-foreign OCONUS per diem (set by the State Department and DoD, not GSA), lodging taxes (which in CONUS are usually reimbursed separately as an actual expense and are not subject to the lodging cap), or the exact first/last-day per-meal deduction tables when an employer prorates by individual meal rather than total M&IE. It also does not model the reduced flat rate for long-term temporary duty (often 55% of M&IE after 30+ days) or conference lodging exceptions. Mileage and airfare to and from the destination are reimbursed separately - personal-vehicle mileage under the IRS standard rate. Always confirm the destination's current rate and your agency's travel policy before filing. Pair this with a mileage-reimbursement calculator and a trip-budget tool for the full picture.

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