Trip Budget Calculator

How to use the trip budget calculator

Start with the two sliders that scale everything else: how many travellers, and how many nights. The calculator treats the party as a unit for the costs you genuinely share and as a crowd for the costs you do not.

Flights and lodging are entered as totals, because two people on one booking pay one lodging bill; food, activities and local transport are entered per person per day, because a second traveller eats a second dinner. Getting that split backwards is the single most common way a trip budget comes out wrong, and it always errs in the dangerous direction.

With the defaults loaded, 2 travellers over 5 nights produce a $3,113 total, $1,556.50 each, or $518.83 for every day the party is away from home. Every dollar in that figure flexes off the two numbers at the top.

Two structural details are easy to miss, and the first is the day count. Spending days are nights plus one: a 5-night trip spans 6 days on the ground, and you buy lunch at the airport on the way out and dinner on the way home.

Counting only the nights would shave a full day of food, transport and incidentals off the estimate, which on the defaults is $230 before the buffer and $253 after it. Lodging still uses nights, because you only pay for beds you sleep in.

Read the result three ways, because each answers a different question. The total is what the trip costs the party and is the number that decides whether it happens at all. Per person is what each traveller owes and is the number you send round the group chat.

Per day is the burn rate, and it is the most useful of the three when you are trying to trim, because a recurring cost compounds over the length of the trip while a one-off does not. Cutting $20 a day from activities on the default trip saves $264 once the buffer is applied; cutting $100 from miscellaneous saves $110.

Leave the 10 percent buffer on while you are deciding, and turn it off only when you are comparing two itineraries where the padding is noise on both sides.

What should the daily fields actually say?

The daily fields are where a destination shows its character, and they deserve more thought than the flight price does because they repeat. A useful sanity check is the per diem the US federal government publishes for its own travellers, since it is dated, public and checkable.

For fiscal year 2026 the standard rate anywhere in the continental United States without its own listing is $68 a day for meals and incidentals, on top of a $110 lodging ceiling. In the expensive cities the meal allowance rises to $92 and the lodging ceiling roughly doubles or triples.

The calculator’s $60 food default sits just under the federal standard rate, which tells you it is a modest but not unrealistic number for an ordinary American destination, and a low one for New York, Boston or San Francisco.

The formula, worked line by line

The budget is a sum of four buckets with a multiplier on the end. Two of the buckets are party totals that you enter directly, flights and miscellaneous. One is a nightly rate multiplied by nights, which is lodging.

One is a daily rate multiplied twice, by the number of people and by the number of days, which is the per diem. Then the whole subtotal is scaled by the buffer, and the result is divided two ways to give the per-person and per-day views.

The only genuine subtlety is the day count. Lodging runs on nights, because a night is what a room is sold by, but eating and moving around run on days, and a trip of five nights occupies six of them. So the per-diem line uses nights plus one while the lodging line uses nights alone.

On a short trip that one extra day is a noticeable fraction of the food budget; on a two-week trip it barely registers. Either way it is the difference between an estimate that survives contact with the trip and one that runs out early.

spending days = nights + 1
lodging       = lodging per night x nights
per diem      = (food + activities + transport) x travelers x spending days
subtotal      = flights + lodging + per diem + misc
total         = subtotal x buffer     (1.10 default, 1.00 exact)
per person    = total / travelers
per day       = total / spending days

Scale it up and the shape holds. Four travellers, 7 nights, $1,200 of flights, $200 a night of lodging, the same $115 daily rate and $200 of miscellaneous: spending days are 8, lodging is 200 x 7 = $1,400, the per diem is 115 x 4 x 8 = $3,680, and the subtotal is 1,200 + 1,400 + 3,680 + 200 = $6,480.

With the buffer the total is $7,128.00, which is $1,782.00 each and $891.00 a day. Notice that the per diem is now more than half the whole budget. On long trips with several people, the daily fields matter more than the flights do.

Two things the buffer is and is not. It is a cushion for the ordinary upward drift of travel spending, the surge-priced ride, the dinner that ran over, the museum with a paid special exhibition, and on the defaults it converts a $2,830 subtotal into $3,113, a $283 pad.

It is not a contingency fund for a cancelled flight or a medical bill, which belong in insurance rather than in a percentage. Turn it off when you want the raw arithmetic for a like-for-like comparison, and leave it on when the question is whether you can afford to go.

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