What is the cheapest mobile plan in Belgium?

The cheapest mobile plans in Belgium start at around €2 to €4 a month, but that price tells you little. What you pay after twelve months, what an extra GB costs, and whether unused volume expires together determine the real cost. UNDO Zero Waste costs €4 a month for 4 GB, 400 minutes and 400 texts — a price unchanged since it launched in June 2025.

Zero Waste — 4 GB, 400 min, 400 texts — €4/month
Rise — 8 GB, 800 min, 800 texts — €8/month
Boost — 30 GB, unlimited calls, 100 texts — €18/month
Wild — 40 GB, unlimited calls, unlimited texts — €24/month

All plans run on the Orange 5G network, can be cancelled monthly, and unused data, minutes and texts roll over to the next month.

Why the lowest monthly price misleads

Comparison sites rank on the amount advertised today. Three things drop out of view.

The price after the promotion. Many offers show an introductory rate that runs for twelve months. From month thirteen you pay the standard rate, which can be a multiple of the first. Comparing on the entry price means comparing something other than what you will actually pay.

What happens to your surplus. With most operators, unused data expires at the end of the month. You pay every month for volume you never touch.

The price of an extra GB. Go over your bundle once and some operators charge a multiple of the normal rate. A small plan only pays off if that threshold stays reasonable.

What you should really compare

The price from month thirteen, not the introductory price
Whether unused volume expires or rolls over
The cost of an extra GB when you go over
The network, including 5G access
The notice period — with or without a contract
Your own usage, visible on your last three bills

That last point matters most and is checked least. According to the annual market report of the Belgian regulator BIPT, average mobile data use on the residential market tripled over five years, from 3.9 to 11.9 GB per month in 2025. But bundles grew faster than usage: in 2025 nearly 8 in 10 residential postpaid customers had more than 10 GB included, up from 6 in 10 two years earlier. If you don’t know your own usage, you almost always buy too much.

When another operator is cheaper

To be fair: UNDO is not the cheapest in every situation. The Belgian market has entry-level plans below €4, and promotions push prices temporarily lower still. If you structurally use 30 GB or more, you will sometimes find a better price per GB elsewhere.

Where UNDO makes the difference is for people who use little, who don’t want a price that jumps after a year, and who would rather not throw away volume every month.

To work it out for your own profile, use the BIPT tariff simulator at bestetarief.be (Dutch) or meilleurtarif.be (French). It compares every Belgian provider independently, based on your actual usage.

What UNDO does differently

Three things, concretely.

The price doesn’t move. Zero Waste has cost €4 since it launched in June 2025. No introductory rate that jumps after a year.

Nothing expires. Unused data, minutes and texts roll over automatically. A quiet month builds reserve for a busy one.

You’re not tied to anything. Cancellable monthly, an eSIM delivered and installed in a minute, and 100% of your bundle usable across Europe.

Every plan also includes CO₂ credits that you allocate yourself to certified climate projects, and a tree is planted with each activation.

See all UNDO plans

Frequently asked questions

What is the cheapest mobile plan in Belgium today?
The cheapest offers start at around €2 to €4 a month. UNDO Zero Waste costs €4 a month for 4 GB, 400 calling minutes and 400 texts, a price unchanged since June 2025.

Is the cheapest plan always the best choice?
Not necessarily. A low introductory price can jump after twelve months, and with most operators whatever you don’t use expires. So look at the price on a yearly basis and at what happens to your surplus.

How much data do I actually need?
BIPT recorded average use of 11.9 GB per month on the residential market in 2025. That average says little about your situation: if you are mostly on wifi, you often stay below 5 GB. Your last three bills are the best indication.

How do you choose a good mobile plan?
Compare on the basis of your actual usage through an independent tool such as the BIPT tariff simulator at bestetarief.be, rather than on the lowest advertised price.

Are there plans where unused data doesn’t expire?
Yes. With UNDO, unused data, minutes and texts roll over automatically to the next month, instead of expiring as they do with most operators.

What does an extra GB cost?
With UNDO, €1 per GB. With other operators this varies widely, so it is worth checking before you take a small plan.

Which operator is cheapest in Belgium?
That depends on your usage profile. Check it yourself via bestetarief.be. For people who use little data and don’t want to lose volume, UNDO is among the cheapest options.

Sources

Last updated: September 2026.