Food is wildly personal, but a realistic baseline I use is $25–$60 per day if I mix street food, grocery runs, and one sit-down meal—so $250–$600 for 10 days. Local transit (metro or bus) might run $3–$12 per day in many cities, so call it $30–$120 total.
Activities and entry fees are the sneaky category: if you do one paid attraction most days, budget $10–$35 per day ($100–$350 total), more for big-ticket experiences. Add insurance (often $40–$150 for a short trip depending on coverage and age), and add paperwork fees when relevant (for example, an ETIAS fee in euros when it applies).
Then add the buffer: I do 10 percent of the total for price spikes, missed buses, and the I-swear-I-didn't-mean-to-spend-that-much-on-snacks tax. When you add those ranges up, a 10-day trip can easily land anywhere from roughly $1,300 on the very scrappy end to $3,500+ if you're paying for private rooms and lots of activities.
The point isn't the exact number—it's seeing where the money actually goes so you can adjust intentionally. A few practical booking notes I've learned the hard way: keep your first and last nights locked in early (arrival-day you doesn't need extra stress), don't book every intercity trip before you've confirmed you can handle the pace, and save confirmation numbers in two places.
I also keep a no-regrets cancellation rule: if a booking is cheap but nonrefundable, I treat it like it's expensive, because the real cost is the flexibility you lose.