G.Fast for Business: Speed, Cost and Availability

The AMVIA Team | 6 min read · Mar 2026

G.Fast sits in a specific slot in the UK broadband hierarchy: quicker than FTTC, weaker than FTTP, and available only in pockets. If you are in a G.Fast coverage zone where full fibre has not yet arrived, it can give your team a meaningful speed lift for a modest monthly cost. The trade-offs matter, though — and they decide whether G.Fast is the right call or whether you should wait. Before you commit, run your postcode through an availability check or our business broadband tool to see every option live at your address.

How fast is G.Fast for business in practice?

G.Fast speed depends almost entirely on the length of copper between the distribution point unit (DPU) and your building. FTTC street cabinets can sit hundreds of metres away; G.Fast DPUs are placed much closer, usually within 50–200 metres of the premises they serve. The shorter the run, the faster the line.

Real-world speeds on G.Fast from Openreach:

• Under 100m from DPU: Download 250–330Mbps, Upload 40–50Mbps
• 100–200m from DPU: Download 150–250Mbps, Upload 30–40Mbps
• 200–350m from DPU: Download 80–150Mbps, Upload 20–30Mbps

Beyond roughly 350–400 metres, performance falls back towards FTTC levels and the advantage evaporates. In practice Openreach only activates G.Fast where the DPU is close enough to deliver a genuine improvement. Ofcom's own connectivity reporting confirms how heavily fixed-line speeds vary by access technology and distance (Ofcom).

Why do upload speeds matter most for G.Fast?

G.Fast upload is far better than FTTC but still asymmetric. The ceiling of around 50Mbps up is fine for most SME workloads — Teams calls, cloud backup, and hosted VoIP for dozens of users. If your business pushes large volumes upward, that ceiling becomes the limit.

For video production, large file transfers, or self-hosted services, the symmetric upload of a leased line (100Mbps and up, both directions) is the better fit. The rule of thumb: download speed sells the headline, but upload decides whether cloud-heavy teams feel the connection is fast.

What does G.Fast business broadband cost?

G.Fast pricing sits close to FTTP products of equivalent speed. For businesses that can order it, indicative pricing on 24-month contracts:

• G.Fast 100–150Mbps: from £35/month
• G.Fast 200–330Mbps: from £35/month

Because these prices overlap with FTTP at similar headline speeds — and FTTP offers better long-term performance and upload symmetry — G.Fast is hard to justify wherever full fibre is also available. Its real value is as a stopgap in areas FTTP has not yet reached.

How does G.Fast compare to FTTP and a leased line?

G.Fast is a shared, contended technology over copper. FTTP runs fibre all the way to the building. A leased line gives you dedicated, uncontended bandwidth that does not flex with what your neighbours are doing. The table below sets the three side by side.

If consistent performance is commercially important, compare the economics directly in our leased line vs broadband breakdown. Where full fibre is live, an FTTP leased line often delivers leased-line reliability on the fibre that has already reached your street.

Where is G.Fast available in the UK?

G.Fast is available only where Openreach deployed DPUs into the relevant cable run, and that rollout was limited and geographically uneven. Some urban and suburban areas got G.Fast; many never did. A postcode check is the only reliable way to confirm it at your address.

Key characteristics of G.Fast coverage:

• Available in some urban and suburban areas that received G.Fast DPUs under Openreach's G.Fast programme
• Not available where standard FTTC cabinets were never upgraded with G.Fast DPU infrastructure
• Where both G.Fast and FTTP are available, FTTP is the clear choice
• Where Openreach deployed neither, FTTC remains the only copper-based option

Should your business choose G.Fast?

Choose G.Fast when it is available at your address, FTTP is not yet deployed, and your current FTTC speeds are holding the team back. It is a sensible middle ground when you need more than FTTC but cannot justify a leased line, and you can accept some performance variability for a lower price.

Choose G.Fast if:

• It is available at your address and FTTP is not yet deployed
• Your current FTTC speeds are inadequate for your team
• You need more than FTTC but a leased line is not justifiable
• You can accept some performance variability in exchange for lower cost

Wait for FTTP instead if:

• Openreach or CityFibre FTTP is planned for your area within 12–18 months
• Your current FTTC is just about adequate and switching now would be disruptive
• You want future-proof infrastructure you will not have to replace again

Whichever route you choose, connectivity is only half the job — the link into your network also needs protecting. The NCSC's small business guidance is a sound starting point for hardening any new connection (NCSC).