What does custom software cost in the UK?

The cost is labour, so it follows what developers cost. A permanent UK software developer had a median advertised salary of GBP 65,000 in the six months to 11 October 2026; the government’s Skilled Worker going rate for the occupation is GBP 54,700. A contract developer’s median advertised day rate was GBP 510. Multiply by the weeks the work genuinely takes, add the work that is not coding, and that is the floor.

Why do custom software quotes vary so much?

Because they are quoting different amounts of work under the same words, and because the uncertainty is real rather than rhetorical. The National Audit Office found that five major government digital programmes expected to cost at least GBP 3 billion more than first planned, about 26 per cent above initial estimates — and the NAO itself cautions that those figures use different formats and price bases.

Is custom software cheaper than off-the-shelf?

Rarely at purchase, often over five years, and almost never if the thing you want is something a product already does well. The question worth asking is whether the difference between you and your competitors lives inside the software. If it does, licensing somebody else’s version of it has a cost that does not appear on an invoice.

How accurate is a software estimate?

Treat any single figure given before the detail is agreed as a range with the error bars removed. Research on 1,471 IT projects found an average cost overrun of 27 per cent, with one in six running far higher — though that sample was 83 per cent US-based and 92 per cent public sector, so read it as a warning about large public programmes rather than a law of nature.

Build cost

What does custom software cost to build in the UK?

Last updated 12 October 2026

Custom software has no list price, so every figure you find for it is really a figure about something else: salaries, day rates, or someone else’s project. Here are those three, properly sourced, and what each can honestly tell you.

1. What the people cost

UK software developer, median advertised permanent salary

£65,000

Six months to 11 October 2026, from 1,240 quoted salaries across 1,448 permanent vacancies, up 8.33% year on year. Source: ITJobsWatch.

Two public cross-checks sit either side of that. The government’s published Skilled Worker going rate for SOC 2134, programmers and software development professionals, is £54,700 a year or £28.05 an hour at 37.5 hours, on a page last updated 8 October 2026. And on the contract side the median advertised day rate for a UK developer was £510 in the six months to 10 October 2026, from 3,486 quoted rates.

A timing note worth having, because it affects every article published this month: the Office for National Statistics’ most recent earnings release is “Employee earnings in the UK: 2025”, published 23 October 2025, covering April 2025, with all 2025 estimates provisional on an achieved sample of 174,000 employees. The 2026 edition is not out until 22 October 2026. Anything citing “the latest ONS data” for developer pay before then is citing figures eighteen months old.

2. What suppliers publish

Rate cards are the one place where UK software prices are genuinely published, because suppliers on the government’s G-Cloud framework must file one. From a January 2026 pricing document, maximum day rates per consultant on a 7.5-hour day, excluding VAT: £1,050 for a developer, £1,450 senior, £1,700 lead, £1,950 principal. A second supplier publishes software development as £250 to £1,100 a day.

Those are maximums on a framework for selling to departments, which is a different market from yours — but they are real published numbers with a date on them, which is more than the usual “£400 to £800 a day” offered without provenance.

3. What goes wrong, with the caveats attached

The National Audit Office examined five major government digital programmes and reported, in January 2025, that they expected to cost at least £3 billion more than originally planned — around 26 per cent above initial estimates — attributing it to resetting programmes and running legacy systems longer than intended.

Three caveats belong with that number and are usually dropped. The NAO itself states the figures “use different formats and price bases and may not reflect current costs”. It is five selected programmes, not a sample of government IT. And the report does not examine individual contracts. It is evidence that large public programmes overrun; it is not a percentage you can apply to a quote for a twelve-week build.

The broader academic figure often quoted alongside it — an average 27 per cent cost overrun, with one project in six a “black swan” — comes from a study of 1,471 IT projects published in the Harvard Business Review in September 2011. Useful, and fifteen years old, with 83 per cent of the sample US-based and 92 per cent public sector.

What it actually comes to

At our own rates, an internal tool that replaces a spreadsheet and a shared mailbox starts around £3,000; a product with accounts, payments and a couple of integrations usually lands between £6,000 and £8,000; a platform with several integrations and regulated data runs from about £20,000 up, all excluding VAT. Those are our prices, and we publish them because the alternative on this question is a range with no provenance.

The thing that moves the figure most is not technology choice. It is whether the data is regulated and how many systems the thing has to talk to — every integration is a place that can break which you do not own.

Sources: ITJobsWatch permanent and contract series for Software Developer and Developer, read 12 October 2026, periods and samples as stated · gov.uk Skilled Worker going rates, updated 8 October 2026 · ONS, “Employee earnings in the UK: 2025”, released 23 October 2025, April 2025 data, provisional · Crown Commercial Service G-Cloud 15 supplier pricing documents, January 2026 · National Audit Office, report on government digital programmes, January 2025, including its own footnote on price bases · Flyvbjerg and Budzier, “Why Your IT Project May Be Riskier than You Think”, Harvard Business Review 89(9), September 2011, n=1,471.

Want the figure for your own system?

Seven questions about what you are building, and the estimate lands in your inbox: a range, a timeline and each stage priced on its own.

Work out what it costs →