Build the exact eSIM for your trip, day by day

Most eSIM plans come in set shapes: 7 days, 15 days, 30 days, a few gigabytes here, a few more there. Trips rarely match them. Yours might be 11 days, or a long weekend that runs Thursday to Monday, or two months in one country. So you pick the nearest bundle and hope for the best. Either you buy the longer plan and pay for days you will spend at home, or you take the shorter one and find yourself topping up halfway through the trip.

The plan builder on our country pages takes the guessing out of it. You choose how much data you want each day and how many days you need, and the price updates as you go. This guide walks through how it works, who it suits, and when one of the regular fixed plans is still the better buy.

Where to find it

Open any country page, for example Japan or Greece. Above the list of plans there is a bar called Build your own plan, with a short line underneath: choose data per day and number of days, and pay only for what you need. Tap the bar and the builder opens. It asks you two questions.

Step 1: how much data per day

The first question is How much data per day?, and the small note beside it is the key to the whole thing: Renews every day. You are not buying one pot of data for the whole trip. You are buying a fresh amount of full speed data every day, for as many days as you choose.

Each option comes with a short hint about what it is good for:

• 500MB per day: WhatsApp, email and maps
• 1GB per day: social media and maps
• 2GB per day: browsing and music
• 3GB per day: short videos and video calls
• 5GB per day: video and work

The amounts on offer depend on the destination. On the Greece and Italy pages the builder currently goes up to 3GB a day, Japan goes up to 5GB, Thailand adds a 10GB option, and the United States has a 1.5GB step in between. Whichever country you open, you only see the amounts that are actually available there.

What happens when you use up the day's amount? You are not cut off. The connection carries on at a slower speed until the next day, when the full speed amount comes back. The summary at the bottom of the builder tells you exactly what that slower speed is for the plan you have built, so there are no surprises after you pay.

Step 2: how many days

The second question is For how many days?, with the note Up to a year. There is a counter with minus and plus buttons, so you can set the exact number, anywhere from a single day to 365. Hold a button down and it speeds up, which saves a lot of tapping when you are planning a long stay.

For the common lengths there are shortcuts: 3 days, 5 days, a week, 10 days, 2 weeks, 3 weeks, a month, 2 months, 3 months, half a year and a year. Tap one to jump straight there, then nudge the counter if your trip is a day or two off.

The price follows every tap

At the bottom of the builder, a summary describes what you have built in plain words: the daily amount at full speed, the number of days, and the speed you drop to once the daily amount is used. Beside it you see the total price and the price per day, and both change the moment you change anything. When it looks right, Buy this plan takes you to the normal checkout.

Two things are worth knowing about the price. The cost per day usually falls as the trip gets longer, so a month works out far cheaper per day than a weekend. And now and then a slightly longer plan costs the same as, or even less than, a slightly shorter one. Before you buy, tap the counter a day or two either side of your number and watch the total. If an extra day costs nothing or next to nothing, take it. A delayed flight home is a lot calmer when your phone still works.

Who the builder suits

Trips with an awkward length. An 11 day holiday falls between the usual plan lengths, and so does a 4 day long weekend, a 19 day honeymoon or a 45 day trip. With the builder you buy 11 days, or 4, or 45, and nothing more.

Long stays. Two months, half a year, a full year: the builder covers any of them in a single plan. That suits a sabbatical, a semester abroad, a relocation, or a long stretch of work in one country, where buying plan after plan gets tiring fast.

People whose days look alike. If your routine is predictable (maps in the morning, messages all day, a video call home in the evening), a fixed daily amount fits better than one big allowance you have to ration. Remote workers and heavy users in particular like knowing that tomorrow starts fresh, whatever today looked like.

Anyone who hates rationing. With one big allowance, a heavy first few days can leave you counting megabytes at the end of the trip. With a daily amount, a busy day never eats into tomorrow.

When a fixed plan is still the better choice

The builder is not always the answer, and it is worth being straight about when it is not.

• Your usage is uneven. If you will barely touch data on most days and then need a lot on one or two (a long drive with navigation and a playlist, an afternoon of uploading photos), a fixed plan with one total lets quiet days pay for busy ones. A daily amount does not carry over to the next day.
• You are crossing borders. The builder works per country, on that country's page. For a trip through several countries, a single regional plan that covers all of them is usually simpler than a separate plan for each stop.
• You need calls or texts. Built plans are data only. If you also want calls and SMS, look at the Data + Calls tab on the country page.
• A fixed plan already fits. If your trip is exactly a week and a fixed plan covers what you need, compare the two. The fixed plans sit right below the builder on the same page, so it takes seconds.

Choosing your daily amount

If you are not sure whether you are a 1GB person or a 2GB person, our guide to how much data you need for travel breaks down what everyday apps actually use, and it pairs well with the builder. As a rough starting point, people who mostly message and navigate do fine on 500MB or 1GB a day. If you scroll social media through the day and stream music on the move, 2GB is comfortable. Video calls, short videos and working on the go point to 3GB and above.

One simple rule helps: build for your normal day, not your busiest one. Because the plan never cuts you off, a day that runs over only means slower data until the next morning. Messages still get through at the slower speed, but video will struggle. So if losing full speed in the evening would really hurt, for example because you work online or the nightly video call home is not negotiable, go one step up.

After you buy

A built plan is a normal eSIM. It arrives the same way as any other plan, with a QR code and installation steps, and it installs the same way too. Do it at home on Wi-Fi a day or two before you fly, so you land connected.

Try it on your next trip

Find your country among all our destinations, open Build your own plan, and set the two things you actually know about your trip: how you use your phone, and how long you will be away. If you want to see how it feels first, try it on the Thailand page, where the options run all the way from 500MB to 10GB a day.