How much custom software costs for a UK small business.

8 August 2026 · 6 min read

Custom software for a UK small business typically costs £8,000 to £30,000 for a first working system. A single automated process sits near the bottom of that range, a multi user platform with mobile apps near the top. Fixed price against a written scope is normal and preferable to a day rate.

Single process£4,000 to £10,000

Business application£10,000 to £20,000

Platform with apps£20,000 to £30,000+

01 Why nobody will tell you the price

Almost every agency website in this country answers the cost question with the words it depends and a contact form. There are two reasons for that, and only one of them is legitimate.

The legitimate reason is that scope genuinely drives cost, and a number given without scope is meaningless. The other reason is that a quote given in a conversation can be adjusted to what the buyer looks like they can afford, which is not a practice that survives being written down.

A supplier who will publish ranges and then hold to them is telling you something about how the rest of the engagement will go.

02 What actually drives the number

Typical UK price bands for a first working system

01How many types of user there are. One user type is simple. Three, each seeing different data with different permissions, is more than three times the work.

02Whether it has to talk to systems you already own. Integration is usually the largest single line and the one most often underestimated.

03Whether it needs to work on a phone as a real application rather than a website. Store submission is its own small project.

04Whether anything is time critical or runs unattended. Background work that must not fail quietly costs more than a button somebody presses.

05How much of the process is already written down. Undocumented processes are discovered during the build, and discovery is the expensive way to find requirements.

03 Fixed price or day rate

A day rate pays the supplier for being slow and penalises them for being fast, which is exactly the wrong incentive. It also transfers all the estimating risk to you, which is the party least able to judge it.

Fixed price forces the scope conversation to happen before money is committed, and that conversation is what determines whether a project succeeds. The catch is that fixed price only works if both sides accept a written list of what is not included, and many buyers find that document uncomfortable. It is protecting you more than it protects the supplier.

04 Questions that reveal whether a quote is real

01What is explicitly not included? A supplier without a ready answer has not scoped it.

02What happens if it takes longer than you thought? On fixed price the answer should be nothing, that is our problem.

03Who owns the code and the accounts, and from when? Day one is the correct answer.

04What do we get at handover? Documentation, credentials, a runbook and a walkthrough is the minimum.

05What does it cost to run per month? Hosting, third party services and, if AI is involved, model usage per user.

Common questions

Is £10,000 a realistic budget for custom software?

Yes, for a focused build. That budget buys one process automated properly with the integrations it needs, rather than a broad platform. Most successful projects start there and expand once the first piece is earning.

Why are offshore quotes so much lower?

Lower cost bases, and often a different definition of finished. The gap usually shows up in integration, handover documentation and who fixes it at month three. It can work well, but compare what is included rather than the headline number.

Should the price include ongoing support?

Support should be a separate, clearly priced monthly arrangement agreed in the same document as the build, not negotiated after go live when you have less leverage and more dependency.

Want a real number for your project?

Describe the process you want removed and roughly when you need it. We will come back with a fixed price and a written scope, or an honest reason not to build it.

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