Business Trip Cost Calculator - Mileage, Per Diem & Hotel

Add up the kilometers, meals, and hotel nights before your boss asks

A three-day business trip with a rental car, two hotel nights, and meals can easily run past $1,000 before you realize it. This calculator breaks the total into five categories - mileage, per diem, lodging, tickets/tolls, and extras - so you can submit an accurate estimate or expense report. It doubles the driving distance for the round trip, subtracts one night from the day count (3 days = 2 nights), and shows what each category costs as a share of the total.

Quick start

Drive 150 miles one way at $0.70/mile, 3 days, $59/day per diem, hotel $120/night, tolls $30.
Mileage: $201.00 | Per diem: $177.00 | Hotel: $240.00 | Tolls: $30.00
Total: $648.00 | Per day: $216.00

How to estimate your trip cost - step by step

One-way distance (miles) - enter the distance from your office to the destination. The calculator doubles it automatically for the return trip. Set to 0 if flying or taking a train.
Rate per mile ($) - mileage reimbursement rate. The IRS standard for business use is $0.70/mile. Your company may use a different rate.
Number of days - total trip days from departure to return. Per diem is applied for each day.
Daily per diem ($) - meal and incidental allowance. GSA rates range from $59 to $79+ per day depending on location.
Hotel per night ($) - nightly lodging cost. Hotel nights equal days minus one (a 3-day trip = 2 nights).
Tickets/tolls and other costs - optional fields for parking, tolls, conference fees, or any additional expenses.
Read the results - total cost, daily rate, percentage breakdown by category, and monthly projection for frequent travelers.

IRS and GSA reference rates

Expense type	Standard rate	Source
Business mileage	$0.70/mile	IRS (2025)
Per diem (standard)	$59/day	GSA (CONUS)
Per diem (high-cost city)	$79/day	GSA (NYC, SF, DC)
Lodging (standard)	$98/night	GSA (CONUS)
Lodging (high-cost city)	$200-$300+/night	GSA (varies)

Trip cost by type - what to expect

Trip type	Days	Typical total	Per day
Day trip (driving, no hotel)	1	$120-$250	$120-$250
Short trip (2-3 days, standard city)	2-3	$400-$700	$180-$250
Week-long conference (high-cost city)	5	$1,500-$2,500	$300-$500
Extended assignment (2+ weeks)	10-14	$3,000-$6,000	$250-$450

Practical examples

Example 1 - day trip, 100 miles each way
Distance: 100 mi, Rate: $0.70, Days: 1, Per diem: $59, No hotel, Tolls: $15.
Mileage: $134.00 | Per diem: $59.00 | Tolls: $15.00 | Total: $208.00

Example 2 - 3-day client visit
Distance: 200 mi, Rate: $0.70, Days: 3, Per diem: $59, Hotel: $120/night, Parking: $40.
Mileage: $268.00 | Per diem: $177.00 | Hotel: $240.00 | Parking: $40.00 | Total: $725.00 | Per day: $241.67

Example 3 - week-long conference in a high-cost city
Distance: 0 mi (flying), Days: 5, Per diem: $79, Hotel: $250/night, Flight: $450, Conference fee: $200.
Per diem: $395.00 | Hotel: $1,000.00 | Tickets: $450.00 | Other: $200.00 | Total: $2,045.00 | Per day: $409.00

Example 4 - minimal day trip, no car
Distance: 0 mi, Days: 1, Per diem: $59, Train ticket: $35.
Per diem: $59.00 | Tickets: $35.00 | Total: $94.00

Example 5 - two-week assignment
Distance: 300 mi, Rate: $0.70, Days: 10, Per diem: $69, Hotel: $140/night.
Mileage: $402.00 | Per diem: $690.00 | Hotel: $1,260.00 | Total: $2,352.00 | Per day: $235.20

FAQ

What is per diem and how is it calculated?

Per diem is a daily allowance for meals and incidental expenses during business travel. In the US, the General Services Administration (GSA) sets rates that vary by city. The standard CONUS rate is $59/day for meals and incidentals. High-cost areas like New York, San Francisco, and Washington DC have rates of $79/day or more. Per diem covers breakfast, lunch, dinner, and tips - not lodging, which is reimbursed separately.

Why does the calculator show one fewer hotel night than trip days?

A 3-day trip means you travel on day 1, stay overnight on nights 1 and 2, and return on day 3. That gives you 2 hotel nights for 3 days. The formula is always nights = days - 1. A 1-day trip means no overnight stay. This matches standard corporate travel accounting and GSA guidelines.

What is the current IRS mileage rate?

The IRS standard mileage rate for business use is $0.70 per mile (2025). This rate covers fuel, maintenance, insurance, and depreciation of your personal vehicle used for business purposes. The rate is updated annually. Medical/moving mileage is lower at $0.21/mile. Your employer can set a higher or lower internal rate, but the IRS rate is the maximum that can be deducted tax-free.

Should I enter distance in miles or kilometers?

The field label says miles, but you can use either unit - just make sure your rate matches. If you enter kilometers, use a rate per kilometer (e.g. $0.42/km instead of $0.70/mile). The calculator simply multiplies distance by rate, so the math works either way. Double-check that you do not mix miles with a per-kilometer rate.

How do I handle a flight instead of driving?

Set the one-way distance to 0 and leave the rate per mile at 0. Then enter the flight cost under Tickets / tolls. The calculator will still compute per diem, hotel, and other costs correctly. The mileage line will show $0 in the breakdown, and your flight will appear under tickets.

What does the monthly projection mean?

For trips of 5+ days, the calculator extrapolates your daily cost to a full month (21 working days) and a full year. This is useful for frequent travelers or managers budgeting annual travel expenses. If a 3-day trip costs $648 ($216/day), the projection shows $4,536/month and $54,432/year at that same daily rate for every working day.

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