Budgeting18 June 20268 min read

How much does custom software cost in the UK?

Most agencies will not put a number on a page. Here are the actual bands bespoke software sells for in the UK, what pushes a project from one band to the next, and how to read a quote so you are comparing like with like.

A laptop showing a business application beside a window

Ask ten UK development companies what custom software costs and nine will tell you it depends. It does depend — but that answer is useless when you are trying to work out whether to raise the subject with your finance director at all.

So here are real numbers. These are the bands bespoke projects genuinely sell for in the UK in 2026, what moves a project between them, and the questions that let you compare two quotes that look nothing alike.

The five bands, with real figures

Almost every custom software project sold in the UK falls into one of five bands. The band is decided by scope and integration count, not by industry — a booking system for a garage and a booking system for a clinic cost roughly the same to build.

Single-purpose internal tool — £6,000 to £15,000. Replaces one spreadsheet or one manual process. One or two user roles, straightforward reporting, four to six weeks.
Departmental system — £20,000 to £60,000. Multiple roles and permissions, real workflow, integrations with your existing systems, proper reporting. Two to four months.
Commercial SaaS product, first release — from £18,000. Multi-tenant architecture, subscription billing, self-service sign-up, an admin back office. Three to five months to something you can sell.
Desktop or hardware-connected application — from £9,000. Native performance, offline capability, device or instrument control, signed installers and an update channel.
Integration and automation work — £3,000 to £20,000. No new interface at all in some cases; just two systems that now talk to each other and a manual job that no longer exists.

All figures exclude VAT. A fixed price should be exactly that — if a quote is a range, ask what makes it the top of the range.

What actually pushes the number up

The cost of software tracks complexity, and complexity has a small number of reliable sources. If you want to know why one quote is double another, it is nearly always on this list.

Number of distinct user roles. Every role means its own screens, permissions, edge cases and testing. Going from one role to four is not four times the work, but it is not far off double.
Integrations with systems you do not control. Each external system is an API to learn, credentials to manage, failure modes to handle and a third party who might change something next quarter.
Data migration from what you use now. Clean data in a sensible structure is cheap to move. Fifteen years of a spreadsheet where the same customer is spelled six ways is a project in itself.
Payments and money handling. Taking payments, splitting them, refunding them, reconciling them and surviving an audit is significantly more work than it looks from the outside.
Regulatory and audit requirements. Retention rules, access logs, exportable records and permission trails add real engineering, and they are not optional in the sectors that need them.
Offline and real-time behaviour. Anything that has to work with no connection, or update several users simultaneously, changes the architecture rather than adding to it.

What brings it down

You have more control over the price than you might expect, and almost all of it is exercised before a line of code is written.

Cut the first release to the process that hurts most. Half the features in a typical wishlist are things somebody thought of in the meeting, and they can be judged properly once the core is live.
Accept sensible defaults on anything that is not your competitive advantage. Custom login screens and bespoke date pickers cost money and win nothing.
Give the developers one decision-maker. Projects with a committee spend a third of their budget on revisions caused by disagreement.
Have your data ready and reasonably tidy. Every hour of cleaning you do yourself is an hour you are not paying a developer to do.
Be honest about how the process really runs. Building the documented process and then discovering everyone works around it is the single most expensive mistake in this industry.

Comparing quotes without being misled

Two quotes for the same project can differ by a factor of three and both be honest. The difference is usually in what is not written down. Before you compare the numbers, make both suppliers answer the same questions.

Is this a fixed price or an estimate? If it is an estimate, what has historically happened to their estimates?
Who owns the code and the repository when you have paid in full? Get it in writing.
Is hosting compulsory, and what does it cost in year two?
What is included after launch — how many weeks of fixes, and what counts as a fix rather than a chargeable change?
Who is actually writing it? A quote from an agency that subcontracts overseas is not the same product as one from the person on the call.
What happens to the timeline and price if we change our mind about something in week six?

The cheapest quote is frequently the most expensive project. The cost of a rescue rewrite is the original budget plus everything you already spent.

Does it pay for itself?

The calculation is more straightforward than people expect. Take the hours per week your team currently spends on the manual process, multiply by a loaded staff cost, and annualise it. A process consuming ten hours a week across a team costs somewhere around £13,000 a year in wages alone — so a £15,000 tool that removes most of it pays back inside eighteen months and keeps paying every year after.

Then add the things that are harder to put a figure on but easier to feel: the orders that stop being lost, the invoices that go out the same day, the reporting that takes a minute instead of an afternoon, and the growth you can absorb without hiring another administrator.

Against off-the-shelf, the comparison is total cost over five years. Per-seat subscriptions look cheap at eight users and look very different at forty — especially since you cannot refuse the price rise, and the workarounds your team invented to make the product fit never go away.

The short version

Internal tools £6k–£15k, departmental systems £20k–£60k, SaaS first release from £18k, desktop apps from £9k.
Cost is driven by user roles, integrations, data migration, payments and compliance — not by your industry.
You control the price mostly through scope decisions made before development starts.
Insist on a fixed price, written code ownership and non-compulsory hosting before comparing numbers.
A tool that removes ten hours a week of manual work typically repays a £15,000 build inside eighteen months.

Questions people ask about this

What is the minimum realistic budget for custom software?

Around £6,000 for something genuinely useful — a focused tool that replaces one manual process end to end. Below that you are usually better served by configuring an off-the-shelf product properly, and we will tell you so.

Why do quotes for the same project vary so much?

Because they are often quoting different things. Fixed price against estimate, in-house against subcontracted, code ownership included against retained, launch support included against chargeable. Normalise those five variables and the spread usually collapses.

Is it cheaper to build in phases?

The total is usually slightly higher, but the risk is far lower and the first benefit arrives months earlier. Most clients are better off launching a smaller first version and funding phase two out of what it saves them.