Cost guide
How much does custom software cost for a UK SME in 2026?
The short answer
A small, focused piece of custom software for a UK SME typically takes somewhere between 10 and 50 days of development, which at common UK day rates of around £500 means roughly £5,000 to £25,000. Larger business systems cost more. On top of the build, budget for hosting plus support and improvement, which is often 15% to 20% of the build cost each year.
Why prices vary so much
Asking what custom software costs is a bit like asking what a building costs. A garden office and a warehouse are both buildings. The useful questions are how much needs to be built, how unusual it is, and what it has to connect to.
The main things that drive cost are:
- Scope. The number of screens, user types, workflows and reports.
- Integrations. Every connection to accounts software, a CRM, payment provider or supplier system adds work and risk.
- Data. Moving existing records from spreadsheets or an old system is often underestimated.
- Rules and exceptions. Pricing logic, approvals and "except when" cases are where the time goes.
- Security and compliance. Personal data, payments and regulated work need extra care.
Day rates in the UK
Most custom software is priced, directly or indirectly, on time. According to IT Jobs Watch, UK contract software developers advertised a median of about £525 a day in the six months to November 2026, with most between roughly £360 and £625. Senior developers were slightly higher. Agencies usually charge more than individual contractors because the price includes design, project management, testing and continuity if someone leaves.
Typical project sizes
These are illustrations based on common UK rates, not quotes. Your own project could sit outside these ranges.
| Type of project | Example | Typical effort | Rough build cost at £500 a day |
|---|---|---|---|
| Internal tool | A quoting calculator or job tracker for one team | 10 to 25 days | £5,000 to £12,500 |
| Customer portal | Clients upload documents and see progress | 20 to 50 days | £10,000 to £25,000 |
| Connected workflow system | Enquiry to quote to job to invoice, linked to your accounts software | 30 to 80 days | £15,000 to £40,000 |
| Core business platform | Replacing a major system the whole business runs on | 80 days upwards | £40,000 upwards |
A good supplier should be able to tell you how they reached their estimate and which parts are least certain.
The costs after launch
Software is not finished when it goes live. Plan for:
- Hosting and services. Servers, databases, email sending and backups. Often modest for SMEs, from tens to a few hundred pounds a month.
- Support and maintenance. Security updates, dependency upgrades and fixing things when connected software changes.
- Change. Your business will change and the software will need to change with it.
A common rule of thumb is to budget 15% to 20% of the original build cost each year for support and improvement. If nobody is responsible for that, the software slowly becomes the next problem.
When custom software is the wrong answer
Bespoke software makes sense when the way you work is a genuine advantage, or when off-the-shelf products force so many workarounds that they cost more than they save. It is usually the wrong choice when:
- A well-known product already does 80% of what you need.
- The process itself is unclear or inconsistently followed.
- Nobody will own the software after it is built.
We compare the options in more detail in off-the-shelf vs bespoke software.
How to avoid overpaying
- Be clear about the problem before the solution. "Quotes take three days and we lose work" is a better starting point than "we need a portal".
- Start small. Build the part that removes the most pain first, use it, then decide what comes next.
- Ask who owns the code and data. You should be able to move supplier if you need to.
- Ask about support before you sign. Response times, monthly cost and what happens if the original developer is unavailable.
- Get a second opinion on large estimates. A clear specification makes quotes comparable.
If you want an independent view before committing, the FiveW Business Review looks at up to three processes and tells you whether software, automation, an existing product or a simpler change is the better route. You own the report and can take it to any supplier.
The FiveW Business Review
Want this answered for your own business? The £750 + VAT review looks at up to three important processes and gives you prioritised recommendations covering likely benefit, cost, effort and risk.
Tell us what is happeningSources
Prices and figures were checked on 8 November 2026 and can change. Always confirm with the supplier.