The 21:10 out of Sofia cost me 34 euros, and the same trip by a day coach plus one hostel bed came to 71. That gap is the reason I book night buses, and it is also the reason the arithmetic happens on paper before anything gets paid, because on a few routes the gap closes before I have finished reading the timetable.
The three numbers I write down
I write down the fare, the arrival hour and the daylight the run saves me. On the leg east to Istanbul those read 34 euros, 05:40 and roughly two hours I would otherwise spend sitting at a terminal. The third number is the one most people leave out, and on short legs it is worth more than the fare itself.
I also write what the bed would have cost anyway. A 22 euro dorm and a 19 euro train put the real comparison at 34 against 41 rather than 34 against nothing, and that single line changes my decision on about one booking in four.
When the arithmetic holds
Three conditions have to hold together. The departure needs to be late enough that I would otherwise pay for a night I am not using. The arrival needs to be early enough to catch a connection or a check-in without burning a day. And the fare needs to sit at least 15 euros under the daytime option, because below that margin the lost sleep eats the saving before lunch.
I add the costs the advert leaves out as well: a 3 euro transfer from the outer terminal, a 2 euro coffee when the station kiosk opens at six, and the night taxi rate I refuse to pay. On the Belgrade run those extras came to 7 euros, which still left the bus ahead, but the margin halved in about four minutes of reading.
My worst result was a 26 euro bus that reached Belgrade at 03:10 with nothing open until eight. I bought a coffee, I sat on a bench, and I was useless until noon. I book that morning as a loss now, whatever the ticket says, and the fare stopped looking cheap the moment I counted the day with it.
What the sleep is worth
I measure it in the crudest way available: how the next day goes. A bus that lets me lie flat with a window that does not rattle leaves me moving before noon. A bus with reclining seats and a screen running until midnight costs me the whole morning after, and in a city I have paid to reach a morning is worth more to me than 15 euros.
The one figure I refuse to quote is a percentage. Sleep quality changes with the road surface, the driver's stops and how many people board at 02:00, so a general claim about overnight travel is worth nothing to me. What I have instead is two years of second-day notes, and they point the same way whenever the bed lies flat.
- Flat bed or close to it: I book it, up to 40 euros.
- Reclining seat, dark cabin, no screens: fine once, rough twice in a row.
- A daylight departure sold as an overnight: I do not book it at all.
The two checks before I pay
First I read the arrival hour on a clock instead of trusting a duration, then I set it against the first connection of the morning. A bus landing at 06:10 for a 06:15 train is not a plan, it is a hope, and a hope cost me a 9 euro rebooking fee the last time I tried one.
Second I look for what is open at that hour. Two all-night cafes near the terminal turn an awkward three hour wait into a cheap breakfast, and knowing the street they sit on is the difference between waiting somewhere warm and walking uphill with a bag at dawn.
Both checks take four minutes on the phone at the counter rather than from the booking screen at home, because timetables move and the operator page moves with them. None of the fare alerts I have subscribed to ever told me the terminal had moved to the other side of the road.
The rule I settled on
Under a 15 euro margin I take the day coach and pay for the bed, because I arrive able to walk. Above it I take the bus and book the connection two hours later than seems sensible, paying for the gap in time rather than in money. The slip of paper with the three numbers on it travels in the same pocket as the passport, and the rule has held for two years of one-way tickets.