Travel Itinerary Budget Planner

Introduction to itinerary-level trip budgeting

A trip budget fails in two predictable places: the calendar and the split. The calendar failure is an off-by-one night — you book a flight out on the 3rd and a flight home on the 10th, mentally call it “a week,” and then pay for seven nights of lodging while budgeting for six, or budget seven days of meals when you are actually eating on eight. The split failure is arithmetic: lodging is billed per room per night, meals are consumed per traveller per day, and flights are billed per seat. Multiply the wrong quantity by the wrong count and a couple’s hotel bill doubles on paper while their food bill halves.

This planner is built around those two failure modes. You give it real arrival and departure dates and it derives nights and days for you, so leap days, month boundaries and daylight-saving transitions cannot introduce a fractional day. It keeps party-level costs (flights, a rental car, a museum pass bought as a family ticket) separate from per-traveller costs (meals) and per-room costs (lodging), then reports the total, the per-person share, the per-day burn rate and the per-person-per-day figure that is the only number comparable across trips of different lengths.

The default rates are not invented. Lodging and meal benchmarks come from the U.S. General Services Administration’s per-diem schedule, which is the federal reimbursement ceiling for government travellers inside the continental United States, and the driving rate is the IRS optional standard mileage rate. Both are published, dated, citable figures. Where no authoritative figure exists — most obviously the contingency buffer — the page says so out loud and leaves the number under your control.

How to use the planner with dates, rooms and travellers

Work top to bottom; every field has a defensible default so a partial itinerary still produces a usable number.

• Currency: Sets the symbol and, more importantly, the number of decimal places. Under ISO 4217 the Japanese yen, Korean won, Icelandic króna, Chilean peso and Vietnamese dong have zero minor units, and the Bahraini, Jordanian, Kuwaiti and Tunisian dinars have three. The planner rounds to the right precision for the currency you pick instead of assuming two decimals everywhere.
• Arrival and departure dates: The dates you physically arrive at and leave the destination. Nights are the whole-day difference; days on the ground are nights plus one. If your itinerary does not fit that pattern — an overnight flight home, a night on a sleeper train, a house-sit where you pay for nothing — switch to manual entry and type the two counts directly.
• Travellers and rooms: Travellers scales meals, activities and the per-person split. Rooms scales lodging. Two adults in one room is 2 travellers, 1 room; two adults who each want their own room is 2 travellers, 2 rooms.
• Nightly lodging rate and lodging tax: Enter the advertised nightly rate for one room, before tax, then the combined occupancy and sales tax percentage. Hotel taxes in U.S. cities commonly land between 12% and 17% and are quoted separately from the room rate; the Federal Travel Regulation makes the same separation, reimbursing lodging tax as a miscellaneous expense rather than folding it into the lodging per diem.
• Meals per traveller per day: One person’s daily food and incidentals. Leave the first-and-last-day rule enabled if your arrival and departure days involve a partial day of eating; that mirrors how federal travel per diem is actually paid.
• Transportation total and driving distance: Transportation is a party total — add every seat on every leg before entering it. Driving distance is round-trip miles, priced at the mileage rate below it.
• Activities per traveller: Tours, tickets, transit passes, tips and souvenirs, expressed per person for the whole trip. A family ticket bought once belongs in the transportation-style party total instead; divide it by your traveller count if you prefer to keep it here.
• Contingency: A percentage applied to everything above. This is the one number on the page with no authoritative source behind it.

Press Calculate trip budget and the result panel returns a category breakdown, two benchmark meters comparing your lodging and meal rates against the federal standard, and three what-if scenarios showing what one more night, one fewer night and a 20% cheaper room actually cost. Copy link writes every input into the URL so you can send a scenario to a travel companion, and Download CSV exports the breakdown for a spreadsheet.

The formula behind the trip total

Step 1 — trip length from the calendar. Both dates are normalised to UTC midnight before subtraction, which removes the daylight-saving problem: a naive local-time subtraction across a spring-forward boundary returns 6.958 days for what is plainly a seven-night stay. The whole-day difference of two UTC midnights is exact across leap days and month ends, because it is an integer count of 86 400 000-millisecond intervals.

Here is nights, is days on the ground, and and are the arrival and departure timestamps at UTC midnight. The relation is the standard hotel convention: a Friday check-in and Sunday check-out is two nights and three days of spending.

Step 2 — lodging, per room and per night, plus tax. Occupancy tax applies to the room subtotal, so it multiplies rather than adds.

with the nightly room rate before tax, the number of rooms and the tax rate as a decimal fraction.

Step 3 — meals, per traveller and per day. With the first-and-last-day rule enabled, the two travel days are paid at 75% and the interior days in full. That is the rule the Federal Travel Regulation applies at §301-11.101, and the algebra collapses neatly.

where is the daily meal rate for one person and is the traveller count. For a single-day trip the bracket would go negative, so the planner clamps it: a one-day trip is charged , not . Disable the rule and the term is simply .

Step 4 — driving. Round-trip distance times the mileage rate.

Step 5 — base total, contingency, and the grand total. Transportation is a party total; activities are entered per traveller and scaled by . The contingency factor applies to the whole base.

Step 6 — money is counted in integers, not floats. Every currency amount is converted to minor units before anything is added. If is the ISO 4217 minor-unit exponent for the selected currency — 2 for the dollar and euro, 0 for the yen, 3 for the Kuwaiti dinar — then a displayed amount is stored as

and every sum, product and comparison happens on those integers. The per-person split then uses a largest-remainder allocation rather than dividing and rounding each share independently, so the shares always reconstruct the total exactly:

Rounding each share independently is the classic way to lose money: three people splitting $100.00 each get $33.33, and the shares sum to $99.99. The largest-remainder rule hands the leftover cent to the first traveller, giving $33.34, $33.33 and $33.33.

Worked example: two travellers, eight days at the federal per-diem rate

Two people fly to Denver, arriving Friday 4 September 2026 and departing Friday 11 September 2026. They share one room and price it at the GSA fiscal-year 2026 standard CONUS rates so the arithmetic is anchored to a published figure rather than a guess.

• Dates 2026-09-04 to 2026-09-11 → 7 nights, 8 days.
• Travellers 2, rooms 1.
• Lodging $110.00 per room-night, lodging tax 14%.
• Meals $68.00 per traveller per day, first-and-last-day rule on.
• Transportation $624.00 (two round-trip fares, entered as a party total).
• Driving 120 round-trip miles at $0.760 per mile.
• Activities $180.00 per traveller.
• Contingency 10%.

Lodging is 110 × 1 × 7 = $770.00 before tax, and 770 × 1.14 = $877.80 after. Meals are 68 × 2 × (8 − 0.5) = 68 × 2 × 7.5 = $1,020.00; note that eight days at the full rate would have been $1,088.00, so the 75% travel-day rule removes $68.00. Driving is 120 × 0.760 = $91.20. Activities are 180 × 2 = $360.00. The base is 624.00 + 91.20 + 877.80 + 1,020.00 + 360.00 = $2,973.00, and the 10% contingency takes the grand total to 2,973.00 × 1.10 = $3,270.30.

That is $1,635.15 per person, $408.79 per day for the party, and $204.39 per person per day. The per-day figure of $408.79 is not a spending rate you will feel — roughly a quarter of the total was the airfare, which was paid once before departure. The burn rate that matters on the ground is lodging plus meals plus activities divided by days, which here is (877.80 + 1,020.00 + 360.00) / 8 = $282.23 per day for the pair.

Comparing service tiers on the same itinerary

The most useful thing a budget model does is hold the itinerary fixed and vary one lever. Every row below uses the identical calendar (7 nights, 8 days), party (2 travellers, 1 room), transportation ($624.00), driving (120 miles at $0.760), lodging tax (14%), first-and-last-day rule and 10% contingency from the worked example. Only the nightly rate, the daily meal budget and the per-traveller activities budget change. Enter any row into the form above and it will reproduce these figures exactly.

Two things fall out of the table. First, the spread is not proportional: tripling the room rate from $70 to $295 does not triple the trip, because $715.20 of transportation and driving is fixed regardless of where you sleep. Second, the jump from the hostel row to the GSA row is $1,044.12 for the pair, while the jump from mid-range to upscale is $2,257.64 — the marginal cost of comfort accelerates. If you are trying to find a cut, the largest single lever in almost every itinerary is the room rate, because it is multiplied by nights and by the tax factor.

Reading the result: which number to actually use

The grand total is the number you need in your bank account, but it is the worst number for comparing trips. A four-day city break and a three-week road trip have incomparable totals. Per person per day is the comparable figure, and it is the one to track across trips: once you know your own historical number — many domestic U.S. travellers land between $150 and $300 per person per day excluding airfare — you can sanity-check any new estimate in seconds.

The two benchmark meters in the result panel put your lodging and meal rates against the GSA standard CONUS figures of $110 and $68. A meter well past the reference line is not a mistake; the federal rate is a reimbursement ceiling for a government employee staying near a work site, and it is deliberately below what a leisure traveller pays in a peak-season resort. What the meter tells you is how far above the federal baseline your choices sit, which is a useful reality check when a trip feels expensive but you cannot say why.

The scenario rows are the practical output. “One more night” shows the true marginal cost of extending — one room-night with tax plus one traveller-day of meals each, which is almost always far less than one-eighth of an eight-day trip, because the airfare does not repeat. That asymmetry is the single most actionable fact in trip budgeting: extending a trip you have already paid to reach is cheap, and taking two short trips instead of one long one is expensive.

Fitting an awkward itinerary into a flat-rate model

Mixed lodging. Four paid nights at $150 and three nights on a friend’s sofa is not a $150 stay. Use the weighted average, (4 × 150 + 3 × 0) ÷ 7 ≈ $85.71 per night, or — better — run the two segments as separate calculations and add the totals, because the tax factor only applies to the paid nights.

Multi-city trips. Calculate each city separately with its own dates, room rate and meal budget, then enter the intercity legs as transportation in whichever run you treat as the master. Averaging Tokyo and Osaka into one nightly rate loses exactly the information you were trying to model.

Overnight travel. A red-eye or a sleeper train is a night you do not pay a hotel for but a day you do eat on. Switch to manual entry and set nights one lower than the date arithmetic would give, leaving days unchanged.

Breakfast included. The GSA meal tiers break the standard $68 rate into $16 breakfast, $19 lunch, $28 dinner and $5 incidentals. If your rate includes breakfast, subtracting the $16 component is a defensible, published-basis adjustment rather than a guess.

Children and dependants. Count them as travellers only if they eat and pay admission at adult rates. A toddler who eats from your plate and enters free is closer to zero travellers than one; splitting the difference by halving their meal allowance and leaving them out of the activities count is usually nearer the truth than either extreme.

Limitations, stated assumptions, and where this model is wrong

This is a planning model, not a quotation. Its assumptions are worth stating plainly:

• The contingency percentage is a stated assumption, not a sourced figure. No government agency, standards body or professional association publishes a recommended travel contingency. The 10% default is a planning convention this page adopts and exposes as an editable field precisely so it is not mistaken for data.
• The service-tier rates in the comparison table are illustrative. Only the GSA reference row carries a published figure behind it; the hostel, mid-range and upscale rows are representative price points chosen to show the shape of the curve, not surveyed averages.
• A flat nightly rate hides real variance. Weekend, seasonal and event-driven pricing can move a room rate by a factor of three between two nights in the same hotel. If your stay straddles a rate change, run the two halves as separate scenarios rather than averaging.
• Lodging tax is entered as a single percentage. Real bills often combine a state sales tax, a city occupancy tax and a flat per-night tourism assessment; the flat component does not scale with the room rate, so a single percentage will drift on very cheap or very expensive rooms.
• The IRS standard mileage rate is a tax rate, not a cash cost. It bundles depreciation, insurance, repairs and fuel into one figure for deduction and reimbursement purposes. If you already own the car and were not going to sell it after the trip, your genuine incremental outlay is fuel and perhaps tolls — commonly less than half the standard rate. Use the standard rate when you are claiming or being reimbursed; substitute a fuel-only figure when you are budgeting household cash.
• Currency conversion is out of scope. The currency selector controls the symbol and the rounding precision required by ISO 4217; it does not convert. Enter every amount in the currency you select, and remember that exchange-rate movement between booking and travel is a real risk this model does not price.
• Per-diem rates are ceilings, not forecasts. The GSA and State Department schedules cap federal reimbursement. They are excellent, dated, citable anchors and poor predictions of leisure market prices in a peak week.
• Nothing here models refundability, insurance, visas, vaccinations, baggage fees, seat selection, resort fees or parking. Those belong in the activities or transportation totals, and they are exactly the line items that cause an otherwise careful budget to run 10% over.

Sources. Lodging and meal benchmarks: U.S. General Services Administration, GSA Per Diem Bulletin FTR 26-01 (FY 2026 CONUS per diem rates, standard rates $110 lodging and $68 M&IE, effective 1 October 2025 – 30 September 2026), gsa.gov, and GSA M&IE breakdowns (tiers $68–$92; the $68 tier is $16 breakfast, $19 lunch, $28 dinner, $5 incidentals; first and last day $51.00), gsa.gov. First-and-last-day rule: Federal Travel Regulation §301-11.101; lodging taxes reimbursed separately from the lodging rate: FTR §301-11.27. Foreign destinations: U.S. Department of State, Office of Allowances, foreign per diem rates set under the Department of State Standardized Regulations, allowances.state.gov. Mileage: Internal Revenue Service Notice 2026-10 (72.5 cents per mile for business use from 1 January 2026) as modified by IR-2026-29 (76 cents per mile from 1 July 2026), irs.gov, with the substantiation rules in IRS Publication 463, Travel, Gift, and Car Expenses. Currency precision: ISO 4217:2015, Codes for the representation of currencies; minor-unit exponents taken from the Maintenance Agency list (SIX Financial Information, ISO 4217 List One, published 1 January 2026).

Questions travellers ask about this budget model