Petrol top-ups, late-night taxis, the round of beers nobody added - the five categories of trip spending that quietly blow your budget.
Most groups budget for the obvious things: lodging, flights, meals, activities. Then the trip ends and the actual cost is 25% over budget, and nobody can quite explain why. The reason is almost always five categories of spending that nobody planned for and nobody tracked live.
Here they are.
Petrol top-ups, late-night taxis, the round of beers nobody added, airport food, and souvenirs. Together they're typically 15-20% of a trip's real cost.
You budget for the rental car. Maybe you remember the insurance. You almost certainly don't budget for:
Rule of thumb: add 30% to the rental quote for these. If the car is £400 for the week, plan for £520.
For an actual breakdown of how to split rental cars when not everyone drives, see how to split rental car costs fairly when not everyone drives when it's out (it's on the editorial roadmap).
You walked or trammed everywhere by day. By 1am, with the metro closed, six of you split into two Ubers heading back to the accommodation. €18 a car, twice. Next night, same thing. Four nights of late taxis and you've quietly spent €150-€200 nobody costed in.
Two ways to handle this:
This is the single most common one. You're at a beach bar. One person stands up and says "I'll get this round". They tap their card. €18 for four beers. They sit back down.
Nobody adds it to the tracker. Across a week-long trip, this is usually 5-10 rounds totalling £80-£150 per person. Each one feels too small to bother logging. They aren't.
The fix is the 30-second rule: add an expense within 30 seconds of paying for it. On a phone, this is a 5-second action. The friction is psychological, not technical.
Or: agree at the start that "rounds even out" - person who buys round one is balanced by person who buys round two. This works only if the group is the same people every night. As soon as one person does five rounds and another does one, you're back to needing a tracker.
Travel days are expensive in unmarked ways:
The fix here isn't process - it's just knowing. Add £40 per person to your trip budget under "travel days". You'll spend it.
On almost every trip, somebody decides to buy presents to bring back for partners, parents, or kids. The default is for that person to pay and never mention it. They take the hit, the trip looks cheaper than it was for them.
Two ways this goes wrong:
Default rule: presents for shared people are shared expenses; presents for individuals are personal expenses. Log them accordingly.
Tips. We have a separate piece on tipping and service charges on group trips because it's genuinely culture-specific. In the US, tip everywhere. In Japan, don't. In most of Europe, round up. The rule that works: agree as a group at the start whether tips are part of the equally-split bill or paid by each person individually.
Our rough rule: take your "obvious" trip budget (lodging + flights + food + activities) and add 18%. If the obvious budget says £600 per person for a 5-day European city break, plan for £710. The 18% is these five categories.
If you actually track every expense in real time (which is the whole pitch of an app like EvenRound), you don't have to estimate at the end. You see the breakdown live. It's also faster than trying to remember on the train home.
For your next trip, create a group and share the link. Have everyone add their own expenses as they happen, including the small stuff. The five hidden categories stop being hidden the moment they're tracked.
Free forever. No signup. Works in your browser in 30 seconds.