A United States trip has no single number: the shape decides it. A week of Manhattan pavements with the evenings on hotel Wi-Fi and a week behind the wheel between parks are the same length on paper and nothing alike once the phone does the work.
The short answer, for a week and for a fortnight
Over seven days, a light traveller who walks one city and puts the phone away indoors lands near 3 GB. Somebody doing the ordinary thing — maps most of the day, photographs to the family thread, a couple of calls home — sits between 5 and 8 GB. A driver, or anyone serving a laptop from the handset, should think in terms of 12 GB and upwards for the same week.
Double the trip and the figure does not quite double, because habits settle and indoor networks absorb the evenings. Two weeks of light use lands near 5 GB, ordinary use between 10 and 15 GB, heavy use at 20 GB or beyond.
Why an American itinerary spends so unevenly
Two things do most of the explaining. The first is that hotel Wi-Fi is common, as are the networks in apartments, coffee places and most restaurants, so the evenings usually cost nothing. A fortnight based in one city can finish under the figure a five-day drive burns through.
The second is distance. Getting between two American places is an hours-long act rather than a short hop, and navigation is the one thing that runs continuously instead of in glances. A map held open on a dashboard for six hours, redrawing the road and re-routing around a closure, is the largest single item on a driving itinerary.
Walking cities have their own version. In New York City the phone comes out at every corner: the subway change, the timed entry, the block whose number you cannot read. Each lookup is tiny. Two hundred in a day are not.
Build the figure from your own handset
Guesswork is unnecessary: the phone has been keeping the record. Open the mobile-data screen in settings, find the per-application list, and read the last full month for the three names that dominate an American trip: the map, the messaging app carrying the photographs, and whichever service takes your video calls.
Now turn those monthly totals into a travel day. Take the map's month, divide by thirty and multiply by four for a driving day: at home it runs in short bursts, here for hours. Leave messaging as it is, then add the calls deliberately: video runs in the hundreds of megabytes an hour, so a nightly half-hour over two weeks is a gigabyte on its own.
Then count the days that spike instead of averaging flat: the arrival day, every day with a long drive in it, and the day something changes. Give each of those double your ordinary figure.
Where it goes: pavements, interstates and the call home
An East Coast city break is the lightest of the three trips people book: New York City on foot, transit apps, timed tickets, every evening back on an indoor network. Even at a busy pace it rarely troubles 5 GB in a week.
A West Coast drive is the expensive one. Los Angeles alone turns navigation into an all-day background task, because the distance between two neighbourhoods is a freeway decision rather than a walk. Head out of Las Vegas towards the desert and the pattern flips: long stretches where what you prepared in the last town matters more than the allowance.
A Florida holiday sits between them and splits in half. The short version — Miami, the beach, a boat whose departure follows the forecast — draws in short bursts: the arrival, the boarding document, the morning weather check. The long version, a stay with relatives running for weeks, uses little on any one day but needs the last covered date to sit beyond the flight home.
Then the call home. The gap to the East Coast is six hours and to the West Coast nine, so the window that suits both ends is narrow and hardens into a nightly appointment. Half an hour of video a night for a fortnight is a real share of a 10 GB allowance.
Matching the number to what is actually sold
The sizes on the USA eSIM page include 1 GB over 7 days, then 3 GB and 5 GB, 10 GB and 15 GB on a 30-day window, 20 GB over 90 days and 50 GB over 180 days. Read it as two decisions: how much, and how long.
For most visitors the honest middle is the 10 GB allowance on a 30-day window — a fortnight of maps and photographs with the calls rationed, and a window that survives an itinerary drifting by a few days. Step up to 15 GB if a laptop travels with you or the trip is mostly driving; step down to 5 GB for a long weekend in one city. When a stay with family runs past a month, choose by the longer window rather than the larger allowance.
With the size settled, the ordered version of getting that line onto the phone is in the USA set-up guide.
Habits that keep the figure honest
None of this asks you to ration the holiday. Four habits pay for themselves:
- Pull the day's route and the destination's own published information while still on an indoor network, so the drive reads a copy instead of fetching one. This matters most on the roads out of Las Vegas.
- Move the nightly call to whichever end of the day you are indoors, and let voice carry the rest.
- Switch off background refresh for apps you never open while travelling, and set video and music to download on Wi-Fi only.
- Keep photographs for the evening upload rather than posting from the passenger seat.
Where the selected plan supports a top-up, starting at a sensible size and adding to it later is a reasonable way to buy. Check that on the listing before you fly.
Tip: The arrival day is the most expensive one on almost every American itinerary: the transfer, the address, the check-in and three people asking whether you got in all fall in the same hour. Sort that first day at home and the whole week reads lower.
When the route touches Canada or Mexico
Canada and Mexico are sold separately, so a land border or a short flight north or south is a second purchase, not a continuation of the first. The same reading applies inside the flag: Puerto Rico, the US Virgin Islands and Guam appear on a listing by name or they are not included.
Size the American plan for the American days only, and treat the days over the border as their own allowance. Anyone weighing this against what a home account charges will find that comparison in the wider USA guide.
Short answers
Is 10 GB enough for two weeks in the United States? For most itineraries, yes, provided the evenings run on an indoor network and video calls are not a daily hour.
How much data does a driving day use? Budget four times an ordinary day of navigation, because the map runs for hours rather than in glances.
Is 5 GB enough for a week in New York City? Usually. A walking city break spends in many small lookups and the evenings are indoors.
Does a United States plan work in Canada or Mexico? Not unless the listing names them. Read the territory line before assuming a border crossing is included.
