Understanding Leased Line Speeds & Costs in the UK

By Nathan Hill-Haimes, Technical Director | 8 min read · Mar 2026

A leased line is a dedicated, uncontended circuit between your premises and the provider's core network. Unlike shared broadband, the bandwidth is yours alone. If you are new to dedicated connectivity, start with our explainer on what a leased line is and the wider business leased line pillar before comparing speed tiers below.

What makes leased line speeds different from broadband?

On a leased line, the speed you order is the speed you consistently receive — at 9am on Monday, at peak times on Thursday, and at every other point in the contract. Broadband advertises a maximum that may only appear off-peak and can fall sharply under real-world load. The difference is contention, not marketing.

Leased lines also run symmetrical: upload equals download. A 100Mbps leased line delivers 100Mbps up and 100Mbps down. That matters for cloud backup, VoIP, video conferencing, and any workload pushing data out of the building as well as pulling it in. Ofcom classifies these as dedicated full-fibre connections distinct from shared services (Ofcom). If you only need a shared service, compare it against business broadband first.

What do leased line speed tiers cost in the UK?

UK leased line pricing falls into four practical tiers — 100Mbps, 500Mbps, 1Gbps and 10Gbps — and location drives the price as much as speed does. A well-connected city-centre postcode costs far less than a rural site needing new fibre. The ranges below are typical 2025 monthly figures for a 36-month term.

• 100Mbps — the most commonly ordered SME tier. Suits 10–40 users on cloud apps, VoIP and video. From £69/month in well-served urban areas, with regional and rural postcodes costing more where new fibre is required.
• 500Mbps — for growing offices where 100Mbps headroom is gone. Priced between the 100Mbps and 1Gbps tiers, with the exact figure driven by your postcode.
• 1Gbps — larger offices (50–200+ users), data-heavy operations, multi-tenant buildings. From £129/month, with location driving the final price.
• 10Gbps — data centres, enterprise campuses, extreme bandwidth. Available in city-centre locations from £349/month.

The lower bound is real: leased lines start from £69/month in well-served urban areas. The fibre rollout under Project Gigabit is steadily pulling more postcodes into that bracket, which is why an availability check beats a generic quote every time.

Why does cost-per-Mbps fall as speed rises?

The single most consistent pattern in leased line pricing is that cost-per-Mbps drops sharply up the tiers. The line install and core port carry most of the cost; the bandwidth on top is comparatively cheap. So buying more speed rarely costs proportionally more. Using one city-centre example:

(Example figures, illustrative only.)

The takeaway: if you expect to need more than 200–300Mbps inside your contract term, ordering 500Mbps or 1Gbps from the outset is usually cheaper than starting at 100Mbps and upgrading later. Mid-contract upgrades often trigger a fresh minimum term and, sometimes, re-installation charges. For multi-site estates, the same logic applies — see our guidance on dedicated internet access.

How do you choose the right leased line speed?

Size the line on three inputs: how many people use it, how much data they push out, and how fast you are growing. Most teams over-index on download and forget upload, then hit a wall when cloud backup and video calls saturate the outbound path. Order for your peak, not today.

• Current user count: allow 2–4Mbps per concurrent user for mixed cloud and comms use. 30 users need 60–120Mbps minimum; 75 users need 150–300Mbps minimum.
• Upload requirements: heavy cloud backup, video production, or remote server access? Double your upload estimate and order to match.
• Growth expectations: if you will need more bandwidth within 36 months, order for your anticipated peak — the cost-per-Mbps maths almost always favours it.

A move to full-fibre also future-proofs you against the PSTN switch-off (completing 31 January 2027), after which legacy copper services are withdrawn. If resilience matters, a FTTP leased line with a diverse backup path is the standard pattern we deploy.

Does a higher-speed leased line get a better SLA?

Not automatically. The SLA tier is chosen at order time and depends on the product, not the bandwidth. A 100Mbps circuit and a 1Gbps circuit can both carry the same 4-hour fix guarantee. The SLA is a separate variable from speed — and worth paying for where downtime is expensive.

That said, the financial impact of an outage rises with speed because operational dependency usually rises too. At 1Gbps, an enhanced SLA — 4-hour MTTR plus a diverse routing option — is worth budgeting from day one rather than bolting on after the first failure. Because a leased line is also your security perimeter's front door, pair it with leased line security so the resilient circuit is matched by a resilient defence.

AMVIA matches the right speed and SLA tier to your real usage, running availability checks across multiple carriers to find the best option at each tier for your exact postcode. One provider, security-first, Microsoft-certified.