Unlimited mobile data: do the maths before you choose

Unlimited data is an appealing promise, and it is easy to see why: no allowance to keep an eye on, no warning text at the end of the month, no video freezing on the train. Yet an unlimited plan costs noticeably more than a well-chosen mid-range one. So the question is not whether unlimited is a good deal in general, but whether it is a good deal for you. Ten minutes is all it takes to find out.

What "unlimited" actually means

In Belgium, an unlimited data plan lets you browse with no volume cap on the Belgian network. That is genuine, and it is comfortable. Three points are nonetheless worth knowing before you sign:

• Speed varies. A single range often comes in several maximum speeds. On our comparison tool some offers even carry it in their name: 200 Mbps, 500 Mbps or 1 Gbps on 5G. Unlimited in volume does not mean equally fast everywhere.
• Abroad, the rules change. Within the European Union you use your plan just as you would at home, but the operator may apply a "fair use" limit to data volume while roaming, even on an unlimited plan. The figure is in the price sheet: one glance before the holidays is enough.
• Sharing your connection. If you plan to use your phone as a hotspot for a laptop, check that this is included on the same terms.

None of these is a trap. They are simply the lines that tell two "unlimited" plans apart.

How much do you really use?

This is the figure that decides everything, and you already have it: your smartphone keeps count (Settings › Mobile data, or Network › Data usage), as does your operator's app or customer area. Note down your last three months.

To give you a sense of scale, a few rough figures:

• messaging, email, browsing and maps: usually a few gigabytes a month;
• music streaming: roughly 50 to 150 MB per hour;
• video calls: roughly 0.5 to 1.5 GB per hour;
• video streaming: about 1 GB per hour in standard quality, 2 to 3 GB in HD.

A simple rule of thumb: take your busiest month, add about 30 %, and look for the plan that covers that volume. If the result stays well below the largest capped bundles, unlimited would have you paying for capacity you do not use. The same reasoning applies to your connection at home — see our guide on choosing your internet speed.

The price of peace of mind

At the time of writing (September 2026), our partners' "Unlimited" plans appear on our comparison tool at 40 to 50 euros a month at full price — brought down to 30 to 35 euros during their current promotion. With the same operators, mid-range plans sit between 20 and 23 euros a month at full price.

At full price, that is a gap of roughly 200 to 360 euros a year, per line. For a household with two or three SIM cards, the calculation is well worth making calmly.

That is no reason to rule out unlimited — it is a reason to choose it knowingly. For some profiles those euros buy real peace of mind; for others they pay for gigabytes that sit unused. Prices change: our mobile comparison tool always shows current rates, ranked by real cost over twelve months.

Who is unlimited the right choice for?

Four situations come up again and again among customers for whom unlimited makes complete sense:

1. You watch a lot of video on the move: daily train journeys, breaks, series on the bus.
2. You regularly share your connection with a laptop to work away from home.
3. Your phone is your main internet connection: student room, second home, a home without a fixed line.
4. You simply never want to look at your usage counter again, and that comfort is worth the difference to you.

If none of these sounds like you, a well-sized mid-range plan is very likely the better deal. And you are not locked in: a residential mobile subscription can be ended at any time, with no early-termination charge — see our article on no-commitment internet. Starting with a plan that fits and adjusting later is therefore a relaxed strategy.

The habit that genuinely saves money

Beyond the choice between capped and unlimited, two habits make the biggest difference to your bill:

• Compare over twelve months, not on the headline price. A promotion lasting a few months followed by the full rate can cost more over a year than an offer that looks less spectacular at the start.
• Look at bundles too. Many internet + mobile offers already include a SIM card. If you have an internet subscription at home, the household's total cost can look completely different.