Prices come in four different shapes
A travel eSIM price can be quoted per gigabyte, per day, per megabyte or per kilobyte, and a reader who treats those as the same unit ends up comparing numbers that mean different things. A1 Telekom Austria's per gigabyte entry figure is €2, with the same rate in the US, the UK, Europe, Switzerland, Thailand, Turkey and Mexico and a higher rate in Japan, while Europe inside the EU comes with the home plan. AeroSims pairs an entry data eSIM at $3.90 with a per gigabyte figure of $0.89, and ALDI Mobile lists an entry plan at AUD 23 with a per gigabyte rate of $2.50.
The other end of the scale is per megabyte and per kilobyte. Afghan Wireless bills by the kilobyte, at AFN 15 in the UK, the US and Saudi Arabia, and more in Germany, Turkey and the UAE. Airtel Sri Lanka sells outbound roaming as pay as you go rather than fixed packages, with a per megabyte charge in Japan, Thailand, India, Austria and France and a small per megabyte rate on its visitor tourist SIM. ALDI Talk's world gigabyte pack costs €9.99 for a week of validity, and its Europe plus North America bundle costs less again for a similar pattern of cover. When you scan the Travel eSIMs rankings, sort by the unit you will actually use.
Daily rates buy predictability, not volume
A daily flat rate removes the guessing. 2degrees charges one daily rate across a long destination list that includes the US, Europe, the UK, Japan, Thailand, Turkey and Mexico, sells a megabyte add-on for listed destinations, and offers an unlimited travel SIM that works only in its home market, with extra days sold by the day. The 2degrees review is worth reading if that home market limit is the catch you are weighing.
3 Denmark takes the opposite route. Its travel bundle is included at no extra cost in the US, Europe, the UK, Japan, Thailand, Turkey and Mexico, the plan's own allowance applies outside the EU, EEA and the UK, and the full allowance works inside them. Entry pricing sits at DKK 150, so the 3 Denmark profile matters most if you already hold a Danish plan.
A1 Slovenija mixes both shapes. A daily travel tariff with a daily data cap covers the US, the UK, the UAE, Serbia and North Macedonia, Croatia has an unlimited data option, Switzerland, the UK and Serbia get a gigabyte pack at €9.99, and EU/EEA travel roams at home rates. On a long trip, a daily tariff is easier to reason about; on a short trip, a capped bundle protects your spend.
Region packs and what the allowance really covers
Regional packs are where price per GB stops being meaningful, because the region decides the allowance. ALDI Mobile splits travel data by zone: the US, Mexico, Europe and the UK get a small data allowance for a week of validity, Japan and Thailand get a smaller gigabyte bundle, and the global travel pack adds minutes and messages on top of its data. Same brand, very different cost per useful megabyte depending on where you land.
Airalo holds €4 across the US, the UK, Germany, Italy, Spain, Japan and Turkey, with Egypt and Armenia priced a little higher. Airhub's cheapest listed country is the UAE at $1.89, with France, Switzerland, the UK and Thailand lower still and the US and Singapore higher. AeroSims offers a standard gigabyte bundle for Germany, Japan and the United States, plus unlimited daily plans for Turkey, Greece and Thailand, so one brand can suit opposite kinds of trip.
4ka works by zone rather than by country. Its travel passes start at €5 for a small bundle across Europe including Switzerland, Serbia and Turkey, and the wider zone reaches Greenland, Canada, the USA, Egypt, Morocco and Tunisia. The UK, Ukraine and Moldova roam at home rates under SLOBODA plans, while Mexico and Japan with Thailand bill per megabyte rather than through a travel bundle, and an unlimited EU plan carries its own EU allowance. The 4ka page shows which zone your route would land in.
Validity decides how long the price holds
The same number can be a bargain for a week and a waste for a month. ALDI Talk's world gigabyte pack at €9.99 is a week of validity, which suits a city break and wastes most of its data on a longer trip. A1 Macedonia's packs carry a month of validity, and the cheapest, at MKD 299, covers Serbia, Albania, Kosovo, Montenegro and Bosnia and Herzegovina, while its Europe and US packs cost more for more data. Both are set out in the A1 Macedonia review.
Airtel (eSIM) sells the same idea as two products: an entry pack at INR 648 for a very short stay, and a global option listed as Global Rs 5999 40GB 90 days; Rs 648 1 day entry that carries a large allowance over a much longer window. Airhub eSIM goes further still with a monthly Ultra plan at $49.99, which suits a long stay or a traveller who would rather not top up. 2degrees sells extra days by the day on its unlimited travel SIM, so a delayed flight costs less than it would with a fixed pack.
Plans that only work in a single country
Some entries on any comparison are not travel products at all. A1 Hrvatska's tourist offer is a Croatia tariff starting at €10.90, so read the A1 Hrvatska profile with that in mind. Africell Gambia sells bundles from GMD 150 that cover Gambia only, and Africell Angola lists a roaming entry price of AOA 4,000, where the destination detail is the thing to confirm.
A1 Serbia mixes both shapes: a Europe travel pack at RSD 1,000 with a large data allowance across a set of European countries, then call rates that stay the same in the UK and Turkey, rise in other destinations and rise again on satellite and sea networks. The A1 Serbia review covers the conditions.
Home tariffs set the baseline too, because they are what a roam everywhere plan is measured against. 1&1 (1und1) lists an all-net flat starting price of €9.99. If your existing plan already roams in your destination, a travel eSIM can be the expensive choice.
A short checklist before you buy
Write down four things for every option: the unit, the allowance, the region and the validity window. Then divide spend by the data you will actually use. A per megabyte charge in Mexico and a weekly bundle in Europe are not comparable, and a daily rate across a long destination list can beat both on a long trip.
Finish with the conditions: what happens when the allowance runs out, whether the pack covers the countries you will cross, and whether buying early shortens validity. The Travel SIMs and eSIMs roundup groups the wider field, and the individual reviews linked above fill in the network detail for each brand.