How to check broadband speed before buying a house

Remote working has made broadband one of the most practically important things to check before buying a property — and one of the least reliably disclosed. A property marketed as having 'superfast broadband' might top out at 35Mbps on a good day. Here's how to get the real picture.

Why estate agent broadband claims are unreliable

There is no regulatory requirement for agents to verify broadband speeds, and 'superfast', 'fibre' and 'fast broadband' have no legally defined meaning in property listings. An agent may quote the area's maximum available speed, not the speed achievable at that specific building's line. The actual speed depends on line length from the nearest cabinet, the technology used (FTTC vs FTTP), and local network congestion.

What to check

• Ofcom's Connected Nations checker. Ofcom publishes broadband availability data by address through their Connected Nations dataset. This shows the predicted download and upload speeds from each ISP that serves the address, based on actual network infrastructure — not marketing claims.
• Full-fibre (FTTP) availability. If full-fibre to the premises is available at the address, it's a different category from fibre-to-the-cabinet (FTTC). FTTP offers symmetrical speeds of 100Mbps–1Gbps with no degradation over distance. Ask whether the property is on or scheduled to be on an FTTP network.
• Mobile coverage. In rural areas, 4G or 5G mobile broadband is often a practical alternative or backup. Check Ofcom's mobile coverage checker for the outdoor signal strength at the address postcode from each major operator.

When to be concerned

A maximum predicted download speed of under 10Mbps is slow by modern standards — working from home on video calls, running a household of devices, and streaming 4K content all push this to its limit. Rural properties without full-fibre on the roadmap and with poor mobile coverage deserve particular attention before you commit.

If you work from home or have specific connectivity requirements, it is worth calling the ISP directly with the full address before exchanging contracts — not just checking a postcode average.

A Property Snapshot report includes Ofcom broadband and mobile data for every UK address — showing predicted speeds and full-fibre availability as part of the full property check.