eSIM for a short 3–5 day trip

Count five. Four nights always spans five calendar days, and the last one is when you check in, get to the airport and watch the flight status — all of which need data. If the return flight is late in the day, make sure the plan covers you until you actually board.

Compare the totals, not the per-day price. Long plans always look better per day, but if the total is higher and you will use four days, you are paying for days you never touch. The exception is if you will be back in the same country within the validity and the supplier's terms allow you to keep using it.

Install as soon as the QR arrives, on home Wi-Fi, so that if it fails you have days to fix it. Starting the validity is a separate event from installing in many cases, but the terms vary by supplier — read the details of the plan you bought before you tap anything.

Check the plan's country list first. If your regional plan names that country you simply carry on. If it does not, you choose between adding a small plan for the day or being offline for it — which is rarely a good idea when you have to find your way back across the border the same day.

The normal remedy is to buy more or top up the way your supplier specifies, and that itself needs internet — so do it on the accommodation's or a café's Wi-Fi. The better prevention is to ring-fence part of the allowance for the journey home from day one and check your usage every evening.

Usually not. You may need SMS verification codes for banking or check-in. The tidy setup is to keep the home SIM in the phone with its data roaming off and let the eSIM handle data alone. What it costs to receive calls or texts abroad is a matter for your home operator, so check with them before you fly.