Leased Line vs Full Fibre Broadband
Full fibre is fast and cheap and shared. A leased line is slower to install, several times the price, and yours alone with a contractual fix time. Which is right depends on what an hour of downtime costs you.
Request a quoteThe difference is not speed, it is what you are promised
Full fibre broadband now reaches speeds that would have been leased-line territory a decade ago, which is why the comparison confuses people. But the headline speed is the least important difference between them. Full fibre is a contended service — you share capacity with everyone else on the same infrastructure, so what you get at four in the afternoon is not necessarily what you got at ten in the morning. A leased line is uncontended: the capacity is yours whether you use it or not.
The second difference is what happens when it breaks, and it is the one that actually decides most cases. Business broadband is fixed on a best-endeavours basis, which in practice can mean days. A leased line carries a contractual fix time, usually a small number of hours, with money attached to missing it. You are not buying speed, you are buying a promise about the worst day of the year.
The third is symmetry. Broadband downloads far faster than it uploads, which suits browsing and streaming and suits video calls, cloud backup and sending large files considerably less. A leased line runs at the same speed both ways. For a business pushing data out rather than pulling it in, that difference is felt daily rather than occasionally.
Side by side
Speed
Full fibre: fast down, much slower up. Leased line: the same both ways, whatever you have paid for.
Contention
Full fibre: shared, so peak times can differ from quiet ones. Leased line: yours alone, all day.
When it breaks
Full fibre: best endeavours, sometimes days. Leased line: a contractual fix time, usually hours, with money attached.
Cost
Full fibre: tens of pounds a month. Leased line: hundreds to thousands, driven mostly by the install.
Install time
Full fibre: days to weeks where available. Leased line: weeks to months, depending on civils.
The middle option
Business fibre with automatic 4G or 5G failover — most of the resilience, a fraction of the cost.
Which one you probably need
- An office where people browse, email and take video calls — full fibre, comfortably
- A site where a day offline costs a day of trading — leased line, for the fix time rather than the speed
- Warehouse or distribution where scanning and dispatch stop without it — leased line, and a failover as well
- Heavy upload — CAD, video, backup, large file transfer — leased line, for the symmetry
- A small office that wants reliability rather than guarantees — full fibre with 4G failover is the honest answer
- A rural site with no fibre at all — the comparison does not apply; 4G or fixed wireless is the real choice
Leased Line vs Full Fibre Broadband — Common Questions
Is full fibre as good as a leased line now?
On headline speed it can be. On the things that separate them it is not: full fibre is contended, so peak-time performance varies, it is much slower uploading than downloading, and it is fixed on best endeavours rather than to a contractual deadline. If none of those matter to you, full fibre is the sensible choice and we will say so.
What does uncontended actually mean?
That the capacity is yours rather than shared with other users on the same infrastructure. On a contended service your speed can vary with what everyone around you is doing; on an uncontended one it does not. For most offices that variation is invisible; for anything running voice or live systems at a busy time, it is the difference.
Is the fix time really worth the money?
Only you can answer that, and the calculation is straightforward: what does a day offline cost your business? Where that number is large, a contractual fix time measured in hours is cheap insurance. Where it is small, paying several times more for a promise you will rarely invoke is not a good trade, and we would rather you did not.
What is the middle option?
Business fibre with an automatic 4G or 5G failover. You get full fibre economics and most of the practical resilience, because a fault degrades service rather than stopping it. It does not give you a contractual fix time or symmetric speed, but for a great many businesses it is the right answer and it is a fraction of the cost.
Can we start with full fibre and move to a leased line later?
Yes, and it is often sensible while a business is growing or a site is new. The leased line install is the slow part, so it is worth starting that process before you urgently need it rather than after. Nothing about the earlier setup is wasted — the phone system and network carry across unchanged.
Does either affect our phone system?
Both carry cloud telephony perfectly well; what differs is behaviour under load. On a contended connection, calls are the first thing people notice degrading when the line is busy, which is fixable by prioritising voice traffic. On a leased line it does not arise. If call quality is the reason you are asking, prioritisation is usually the cheaper fix.
More Connectivity / Network Solutions
- Superfast Broadband
- How Much Bandwidth Does a Business Actually Need for VoIP?
- Ethernet & Leased Lines
- What Actually Determines the Cost of a Business Leased Line
- GSM & 4G/5G Backup
- Network & Cabling
- SD-WAN for Multi-Site Businesses
- Business Wi-Fi and Managed Wireless
- 4G and 5G Failover: A Backup That Takes Over By Itself
- Guest Wi-Fi for Business
- Wi-Fi Surveys: Finding Out Before You Buy
Not sure which side you are on?
It usually comes down to one question: what does an hour offline actually cost you? Tell us that and what your people do all day, and we will tell you which fits — including when full fibre with a failover does the job and the leased line would be money spent on a promise you will never call in.