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Per Diem Calculator

Calculate per diem travel allowances for meals, lodging, and incidentals based on destination and federal/company rates.

Tested tool guide Tested browser tools Checked August 16, 2026

What Per Diem Calculator does, with a checked example

This calculator takes a nightly lodging rate, a daily meals-and-incidentals (M&IE) rate, and a trip's departure and return dates, then totals the reimbursement owed for the stay: the full lodging rate for each night stayed, plus M&IE for each day, with the first and last calendar day of travel paid at 75% of the M&IE rate under the standard federal travel rule. You supply the rates yourself, whether a GSA locality rate you looked up or a flat company rate - the tool does not fetch or verify current rates. The detail people miss most: the 75% cut applies only to M&IE, never to lodging.

Worked example

A concrete input and expected output from the current implementation.

Input

Destination: Washington, DC. Lodging rate: $258/night. M&IE rate: $79/day. Trip: depart Oct 1, 2026, return Oct 4, 2026 (3 nights).

Expected output

Lodging: 3 nights x $258 = $774. M&IE: 2 full days x $79 = $158, plus 2 travel days (Oct 1 and Oct 4) at 75% of $79 ($59.25 each) = $118.50. M&IE subtotal $276.50, rounded to $277. Total per diem: $1,051.

Lodging is billed at the full nightly rate for all 3 nights stayed; M&IE is paid at the full $79 rate for the 2 full days at the destination and at 75% for the departure and return days, per the federal first/last-day travel rule.

How the result is produced

1

Inputs and totals

You enter a nightly lodging rate, a daily M&IE rate, and the trip's departure and return dates. The tool counts nights for lodging (one per night stayed) and days for M&IE (one per calendar day of travel), multiplies each by its rate, and sums the two subtotals into a single reimbursable total for the trip.

2

First/last day proration

Per 41 CFR 301-11.101, the day of departure and the day of return are each paid at 75% of the full M&IE rate rather than the full rate, since a traveler is assumed not to incur a full day of meal expense on a day spent partly in transit. Full days at the destination are paid at 100%. Lodging is never prorated - each night stayed is billed at the full rate entered.

Good uses

  • Filling out a travel expense report for a multi-day business trip against a known per diem rate
  • Checking a federal employee or contractor per diem reimbursement before submitting a travel voucher
  • Comparing a company's flat per diem policy against a GSA locality rate to see if it under- or over-pays

Limits and checks

  • The tool totals whatever rate you enter; it doesn't look up or validate that the rate matches the current GSA locality table for your destination and travel dates - rates change every federal fiscal year on October 1.
  • Per diem lodging is a rate cap, not a reimbursement of actual hotel cost; if your employer reimburses actual receipts up to the per diem rate instead of paying the flat rate, the total here won't match your actual payout.
  • The 75% first/last-day rule is the federal travel regulation default; many private companies and some agencies use their own proration or pay a flat daily rate regardless of travel day, so the total may not match a non-federal employer's policy.

Common questions

Does this calculator know the current GSA per diem rate for my destination?

No. It only totals the lodging and M&IE rates you enter; it does not look up or store GSA locality rates. Find your destination's current rate on the GSA per diem rate lookup before entering it here, since rates are set annually and vary by location.

Does it handle per diem for trips outside the continental US?

It can, if you enter the correct OCONUS or foreign per diem rate yourself - those are set by the Defense Department (OCONUS) or State Department (foreign areas), not GSA, and use separate rate tables. The calculator's arithmetic is the same either way; finding the right rate is on you.

References and verification

The example and behavioral notes were checked against the browser implementation. Standards and primary references below define the relevant format, formula, or platform behavior.

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