G.Fast Broadband: The Business Guide

Nathan Hill-Haimes — Technical Director. 6 min read. Published March 2026.

G.Fast — sometimes written G.fast — emerged as a stepping stone between FTTC and full-fibre FTTP. By pushing fibre closer to the premises and using a short copper run from a small distribution point rather than a street cabinet, it can deliver download speeds up to 330Mbps and upload speeds up to 50Mbps. In theory that is near-fibre performance without laying fibre to every building. In practice, the technology has been overtaken by full fibre. This guide explains how G.Fast works, what it delivers, and whether it deserves a place on your shortlist when you compare business broadband options.

How does G.Fast actually work?

G.Fast builds on the FTTC model with one critical change: the copper run is far shorter. FTTC runs fibre to a street cabinet and copper the rest of the way — often a few hundred metres to hundreds of premises. G.Fast instead uses small distribution point units (DPUs) mounted much closer to the building, sometimes on a nearby telegraph pole or lamp post.

That short copper run matters because DSL technologies lose speed with distance — every additional 100 metres of copper costs throughput. With a 50–100 metre run from a G.Fast DPU, speeds in the hundreds of megabits per second become achievable on existing copper, no new fibre to the door required. The UK's broadband infrastructure and the shift toward gigabit-capable networks are tracked in Ofcom's Connected Nations reporting (Ofcom).

What speeds does G.Fast deliver in practice?

In real deployments, BT Openreach G.Fast typically lands at 100–330Mbps download and 30–50Mbps upload, depending on copper length and line quality. That is a big jump over standard FTTC, but it is still asymmetric and well short of the symmetric gigabit speeds FTTP can reach.

Here is how the three technologies compare for a typical UK business:

The takeaway: G.Fast meaningfully outperforms FTTC, but it does not match full fibre on raw speed, upload symmetry, or longevity.

How widely available is G.Fast in the UK?

G.Fast has had a limited and frankly disappointing UK rollout. Openreach deployed it across a series of trial areas and some commercial sites, but never scaled it to the nationwide footprint first anticipated. The reasons are commercial and technical: FTTP delivers better long-term value, and Openreach has shifted investment squarely toward full fibre.

The result is that G.Fast reaches a relatively small number of UK premises. If your building is in a coverage area, it may surface in your ISP's availability checker alongside FTTC and FTTP. Meanwhile, full-fibre coverage keeps expanding rapidly under the government's Project Gigabit programme (gov.uk), which is why the window in which G.Fast makes sense is narrowing.

G.Fast vs FTTP: should you wait for full fibre?

Where both G.Fast and FTTP are available, the recommendation is straightforward: prioritise FTTP. Full fibre wins on every measure that matters for a growing business, and the pricing gap is usually small enough that the performance difference settles the question.

Full fibre delivers:

• Higher maximum speeds — up to 1Gbps and beyond
• Far better symmetry, with upload speeds close to download
• Future-proof infrastructure that will not need replacing
• Consistent performance regardless of line length or copper condition

G.Fast earns its place in one specific scenario: your FTTC is genuinely inadequate and FTTP is not yet available at your premises. In that gap, G.Fast can be a real improvement. But given the pace of FTTP rollout, businesses that can sustain their current connection for a while are often better served waiting for full fibre — or moving straight to a dedicated FTTP leased line if uptime is mission-critical.

What does G.Fast cost for business?

Where it is available, G.Fast business pricing typically starts from £35/month on a 24-month contract — broadly similar to FTTP at equivalent speeds. That pricing overlap is exactly why FTTP tends to win: comparable monthly cost, materially better performance and longevity.

If your priority is guaranteed speed, an SLA-backed connection and a fixed repair time rather than best-efforts copper, the relevant comparison is not G.Fast versus FTTC at all — it is a business leased line versus shared broadband. Leased lines start from £69/month and deliver symmetric, dedicated bandwidth with guaranteed availability.

Should your business invest in G.Fast?

For most UK businesses weighing a connectivity upgrade, G.Fast is not the headline. The sharper question is whether FTTP is available at your premises via Openreach, CityFibre or another network. If it is, take it. If FTTP is not yet there and your FTTC is genuinely holding you back, G.Fast is worth evaluating as an interim step.

But the combination of limited availability and the steady march of full fibre to most UK premises makes G.Fast a niche call rather than a mainstream recommendation. Survey data suggests one in five (20%) UK businesses report internet speeds that fall short of their needs (Uswitch business broadband research / TechUK) — and for those firms, the fix is usually FTTP or a leased line, not G.Fast.

How do you check what's available at your address?

The only way to know your real options is a premises-level availability check across every network, not a postcode-level guess. BT's checker will show G.Fast where it has been deployed at your cabinet and distribution point, but not all checkers separate G.Fast from standard FTTC clearly.

AMVIA checks FTTC, G.Fast, FTTP and leased line availability simultaneously across all major UK networks for your specific premises, returning a complete view of your upgrade paths in one place. One provider, security-first, Microsoft-certified — so the connection you choose is built to carry your business safely, not just quickly. For a wider view of the trade-offs, our guide on whether fibre broadband is right for your business walks through each option.