Per Diem Calculator (Business Travel)
Calculate per diem total for business travel based on city rate, days, and partial-day allowances.
What this calculates
Per diem covers meals, incidentals, and sometimes lodging for business travelers without itemized receipts. US federal travel uses GSA published rates by city. This calculator totals per diem across trip days with the standard 75 % rule for first and last days of travel.
Formula & how it works
Total = (full_days × full_rate) + (partial_days × 0.75 × full_rate). First and last travel days typically claim 75 % per IRS / GSA rules. Lodging is usually separate from M&IE (meals + incidentals) per diem. Federal CONUS rates: standard $59-79 M&IE; high-cost cities $79-92 (NYC, SF, DC). International OCONUS rates set by State Department.
Worked example
5-day Chicago trip (3 full days, 2 partial). Standard M&IE = $79. Total = 3 × $79 + 2 × $79 × 0.75 = $237 + $118.50 = $355.50. Plus separate lodging per diem of $209/night × 4 nights = $836. Total trip per diem reimbursement = $1,191.50.
Frequently asked questions
Lodging vs M&IE?
Federal travelers get separate rates. M&IE = meals + incidentals (tips, dry cleaning, small items). Lodging is usually reimbursed at actual cost up to the per diem cap. Many corporate travel policies bundle them differently.
Where are GSA rates?
gsa.gov/travel/plan-book/per-diem-rates. Updated annually in October. International rates: state.gov/travel/per-diem-rates. Cities are categorized into standard, high-cost, and seasonal variants.
Is per diem taxable?
Not if you're traveling for an employer and the per diem matches or is below the federal rate, and you submit a brief expense report. Above-rate or excess amounts become taxable income.
What's the partial-day rule?
First and last days of travel get 75 % of the daily M&IE rate. Mid-trip days are 100 %. Some employers use flat 100 % all days; most follow IRS 75 % convention.