Per Diem Calculator
Estimate total per diem allowance and remaining amount after out-of-pocket covered expenses.
What this result actually means
Estimate total per diem allowance and remaining amount after out-of-pocket covered expenses. The page keeps the formula visible—Allowance = days × daily rate; remaining = allowance − covered out-of-pocket expenses.—so you can see exactly which assumption moves the answer instead of treating the calculator as a black box.
Use the daily rate and eligible day count that actually apply to the trip. The remaining amount is a cash comparison only; reimbursement and tax treatment depend on the applicable policy and substantiation rules.
Inputs that control the answer
Pay and housing calculators are planning tools: they make the arithmetic explicit, but payroll rules, lease terms, taxes, benefits, and legal obligations can change the real cash result.
| Input | Example | What to enter |
|---|---|---|
| Eligible days | 5 | Enter the count that belongs to the same scenario as the other inputs; avoid mixing totals from different periods or project sections. |
| Daily per diem rate ($) | 68 | Use the current quote, contract rate, or price that applies to this scenario. Small price changes can materially move the final cost. |
| Lodging paid out of pocket ($) | 0 | Use the value that applies to the exact scenario you are modeling; keep its units consistent with the label. |
| Meals / incidentals paid out of pocket ($) | 210 | Use the value that applies to the exact scenario you are modeling; keep its units consistent with the label. |
Worked example
Using the example values loaded in the calculator (Eligible days = 5, Daily per diem rate = 68, Lodging paid out of pocket = 0, Meals / incidentals paid out of pocket = 210), the browser-side formula produces the outputs below. These are example numbers, not recommended project or business settings.
| Output | Example result |
|---|---|
| Per diem allowance | $340.00 |
| Entered covered expenses | $210.00 |
| Allowance minus expenses | $130.00 |
First checkpoint: Per diem allowance = $340.00. Change the inputs to your real scenario before using the number for an order, budget, quote, bid, reimbursement, or operating decision.
Where estimates go wrong
- Confusing gross pay with take-home pay.
- Assuming a premium, commission, per diem, or lease fee applies without checking the governing policy or agreement.
- Mixing one-time costs with recurring monthly costs.
Use the daily rate and eligible day count that actually apply to the trip. The remaining amount is a cash comparison only; reimbursement and tax treatment depend on the applicable policy and substantiation rules.
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Questions people run into
How do I calculate a per diem allowance?
Multiply eligible days by the daily rate. The page then compares that allowance with the lodging and meal/incidentals expenses you enter.
Is unused per diem always mine to keep?
That depends on the reimbursement plan and applicable rules. The “remaining” figure is only the arithmetic difference between entered allowance and entered expenses.
Does this know current government per diem rates?
No. Enter the rate that applies to your trip or policy and verify current official rates separately when relevant.
Method and limits
Formula: Allowance = days × daily rate; remaining = allowance − covered out-of-pocket expenses.
The calculator runs locally in your browser from the values you enter. The mathematical result is deterministic from those inputs; the planning accuracy depends on whether the inputs represent the real job, route, policy, product, or operating conditions. When the result is close to a purchase threshold, package boundary, safety limit, or financial break-even point, verify the controlling assumption before acting.
Reviewed for calculator depth and clarity · September 2026 · Methodology