A 100Mb leased line in the UK typically costs between £150 and £450 per month on a 36-month term, with installation ranging from free (subsidised) to around £2,000 or more where civil works are needed. Pricing is location-driven, so your exact postcode and distance from fibre matter far more than the headline speed itself.
What drives the price
A leased line is a dedicated, symmetric connection reserved for your business alone, which is why it costs more than shared broadband. Unlike contended broadband, your bandwidth is yours whoever else is on the street, and it comes with a Service Level Agreement (SLA) that guarantees uptime and a fix time — typically around 5 hours. You are not just buying speed; you are buying a contractual commitment to keep you online.
The final figure is shaped by a handful of factors that combine differently at every address, so two firms on the same street can receive very different quotes. The single biggest driver is the physical build to your building: if fibre already terminates nearby, install is cheap or free; if a new duct or road crossing is needed, excess construction charges apply.
- Bandwidth — higher speeds cost more, but the jump is smaller than people expect
- Location — distance from the nearest fibre and whether new civils are needed
- Contract term — longer terms (36–60 months) usually lower the monthly cost
- Resilience — diverse routing and failover add cost but remove single points of failure
- Carrier availability — more networks at your postcode means more competition on price
- SLA tier — a faster guaranteed fix time nudges the monthly price up
Indicative monthly ranges
As a rough guide for UK businesses in 2026, most leased lines fall in the bands below. Treat them as a starting point — a quote for your specific postcode is the only accurate figure. If you want a fully symmetric, uncontended connection, a dedicated internet access circuit sits at the higher end of these ranges. Where full fibre is available to the premises, an FTTP leased line can bring the entry cost down further.
One point worth understanding: the 'bearer' and the 'speed' are separate. A 1 Gbps bearer can be delivered at a lower initial speed and upgraded later with a simple configuration change rather than a new install — useful if you expect to grow. Paying for a larger bearer up front can therefore save disruption down the line.
- 100 Mbps — £150 to £450 — small-to-mid offices
- 500 Mbps — £250 to £450 — cloud-first teams
- 1 Gbps — £300 to £600 — busy, growing SMEs
- 10 Gbps — £800+ — data-intensive / multi-site
The 100Mb leased line in detail
A 100Mb leased line gives you a fixed, symmetric 100Mbps down and 100Mbps up, all day, whoever else is on the street. For a typical UK business in a well-served area, a 100Mb symmetric circuit on a 36-month term, with free install and a managed router, lands broadly in the £200 to £450 per month range nationally. In London — the most competitive leased line market in the UK — on-net central buildings can start from around £150 per month.
For most small and medium offices, 100Mbps symmetric is comfortable: it handles Microsoft 365, video calls, cloud backups and VoIP with headroom for roughly 20 to 50 users depending on usage. Where it starts to feel tight is heavy, simultaneous data movement — large media files, frequent multi-gigabyte uploads — or a growing headcount pushing past 40 to 50 people. If that is your trajectory, size up rather than run close to the ceiling.
Leased line costs in London
London has multiple carriers holding fibre in the ground, which drives prices down compared with rural sites. For a fully managed, symmetric 100Mb circuit, central London on-net buildings typically run around £150–£250 per month with install often waived on a 36-month term. Greater London and suburban sites tend to sit at £180–£320 per month depending on carrier reach.
Two firms on the same London street can still receive quotes hundreds of pounds apart for an identical 100Mbps, because it depends which carriers already have fibre near your postcode and how far your building sits from their network. Competition between carriers in the capital tends to keep pricing sharper and installs faster. Our team can quote leased lines in London across every available carrier.
Bearer vs speed: the choice that affects cost
This is the detail most buyers get wrong, in both directions. A leased line has two figures: the bearer (the physical port capacity — commonly 100Mb, 1Gb or 10Gb) and the speed (the bandwidth actually activated). A '100Mb on a 1Gb bearer' means you have a gigabit-capable port but pay only for 100Mb of throughput today.
Why it matters: on a 100Mb bearer, 100Mb is your ceiling — to go faster you need a physical re-install, which means a new lead time. On a 1Gb bearer, upgrading from 100Mb to 200Mb, 500Mb or the full 1Gb is a software change the provider actions in days, with no new fibre build. The premium for the larger bearer is usually modest against the total contract value — often £20–£50 a month.
A practical rule: size the bearer for the next three to five years and the speed for today. If there is any realistic chance you will need more than 100Mbps within the term — more staff, heavier Microsoft 365 use, video, cloud backups, or a move to SD-WAN across multiple sites — the 1Gb bearer is the sensible hedge. If budget is genuinely tight and the site is stable, a pure 100Mb bearer keeps costs lower.
- 100Mb service on a 100Mb bearer — cheapest, but capped; a future upgrade means a new install
- 100Mb service on a 1Gb bearer — small premium, instant upgrades up to 1Gb later
- Add a second diverse circuit or 4G/5G failover for resilience where downtime is costly
One-off vs monthly costs
Watch for installation and 'excess construction charges' (ECCs) — the cost of building fibre to buildings that don't yet have it. Many providers waive or reduce install fees on longer contracts, and installation is frequently advertised as 'free', which usually means the standard build allowance (often up to around £2,800 of construction) is absorbed on a longer term. Always ask what's included before comparing headline prices.
Excess construction charges are the most common reason a quote changes after the initial estimate, as they only become clear once a formal survey is carried out. They can range from nothing to several thousand pounds depending on how much digging or wayleave permission is needed. Always ask whether your quote is pre-survey or confirmed before you commit. Businesses running several offices should also factor in multi-site connectivity and, where uptime is critical, a second circuit for backup connectivity.
What else affects the total cost of ownership
The headline monthly rental is only part of the picture. A managed router, static IP addresses and proactive monitoring may be bundled or charged separately, so compare like for like. Some providers include a managed router; others rent it separately or expect you to supply your own. Static IPs are usually included, but confirm how many.
Consider the service level agreement too — a circuit with a faster fix time and financially backed uptime guarantee typically costs a little more but reduces the risk of costly downtime. If you need a firewall, that's typically a separate line item, worth planning alongside your wider network security rather than bolting on afterwards. For most businesses, the support wrapped around the line matters as much as the price of the line itself.
- Whether installation is truly free or deferred into the monthly rate
- Early termination charges if you move premises before the term ends
- Managed router versus bring-your-own, and who supports it
- Number of usable static IP addresses included
- Cost of adding resilience or a diverse second line later
- What the SLA actually guarantees, and the compensation if it's missed
Install lead times
A fresh install commonly takes 45 to 90 working days, driven mainly by any civil works and wayleave consents. Sites with existing fibre in the building can be considerably quicker. Always treat quoted timescales as estimates until a survey confirms the build.
How to get the best price
Because availability and pricing differ by carrier and postcode, the best approach is to compare the whole market rather than accept a single quote. A carrier-neutral partner does this for you and manages the install and support — often for the same or less than going direct. An accurate quote requires your exact installation address, because pricing is generated from a network availability check against that specific location.
When you request pricing, ask for the numbers broken down clearly so you can compare like for like. A vague 'from £199' headline hides the detail that determines your real cost. If you're based in the capital, our team can quote leased lines in London across every available carrier, or contact us to discuss your requirements.
- Full installation postcode and building details
- Bearer size and committed speed (e.g. 100Mb on a 1Gb bearer)
- Contract term and the monthly cost at that term
- Any Excess Construction Charges before you sign
- SLA fix-time target and uptime guarantee
- Realistic install lead time in working days
