Calculate your per diem
How per diem works
A per diem is a fixed daily allowance paid to cover travel expenses such as lodging, meals, and incidental costs. Government agencies and many companies use per diem rates to simplify reimbursement and avoid tracking every receipt.
Lodging
The lodging portion reimburses the cost of an overnight stay. It is calculated per night, so a 3-day trip typically includes 2 billable nights.
Meals & Incidentals (M&IE)
The M&IE rate covers meals and small incidentals like tips and laundry. Under the GSA convention, the first and last travel days are reimbursed at 75% of the full M&IE rate.
The formula used here
- Nights = travel days − 1 (minimum 0)
- Lodging total = nights × lodging rate × travelers
- M&IE total = rate × (days − 0.5) × travelers for trips of 2+ days, or rate × 0.75 for a single day
- Grand total = lodging total + M&IE total
Frequently asked questions
Is this an official government calculator?
No. This tool is an independent estimator. It uses the standard GSA-style per diem formula but does not pull live official rates. Always confirm rates with the relevant authority (e.g., GSA.gov for U.S. federal travel).
Why is the first and last day only 75%?
Federal per diem rules treat travel days as partial days because travelers are usually not on location for the full day. The M&IE rate is therefore reduced to 75% for the first and last day of travel.
How are nights counted?
Nights are the number of overnight stays. A trip from Monday to Wednesday is 3 travel days and 2 nights. This calculator subtracts one night automatically.
Can I use this for multiple travelers?
Yes. Enter the number of travelers and the totals multiply accordingly. Some organizations negotiate group rates, so confirm with your finance team.
Does the calculator include taxes and fees?
No. Lodging rates here are treated as the per-night allowance only. Taxes, resort fees, and other charges may be handled separately by your reimbursement policy.