Only as a rough guide. An online valuation gives a fast statistical range from averages and public data, but it cannot see your condition, finishes, light or PEB rating, so it can be off by tens of thousands of euros. Treat it as a starting point, then confirm with a free on-site valuation.
Online estimators are useful for orientation and misleading if you trust them too far. They work by matching your postcode and surface area to averages and past transactions, which is fine for a first sense of the range. The problem is that the very things that set your property apart, a recent renovation, a rare garden, a difficult layout, an energy rating, are invisible to the model.
That blindness has a real cost. In Wallonia the PEB certificate is mandatory to sell, rent or advertise, and a poor F or G rating measurably lowers both price and buyer demand, while a strong rating supports the price. An online tool typically averages this away. Two identical-looking houses on paper can be worth very different amounts once you factor in the energy label alone.
Market speed compounds the issue. Prices in Wallonia rose 15.4% in 2025 to a median house of 240,000 euros (source: Notaire.be / Fednot, February 2026), and models trained on older sales lag a rising market. The counter-intuitive result is that the faster prices move, the less reliable a free online estimate becomes, precisely when accuracy matters most.
None of this makes online tools useless. Used as a sanity check around a professional figure, they add value. Used as the basis for an asking price, they invite either a home that sits unsold or one that sells for less than it should.
At a glance
Limits of an online valuation:
- Cannot see condition or finishes: a renovated interior and a tired one read the same.
- Ignores light, noise and outlook: factors that visibly move real offers.
- Averages out the PEB: yet an F or G rating cuts price and demand in Wallonia.
- Lags a rising market: the 2025 Walloon surge outran older transaction data.
- No local nuance: two streets apart can mean two different price levels.
- Best used as: a rough range to confirm with a free on-site valuation.