Guide
How much does custom software cost, and when is it worth it?
Custom software in the UK costs from around £500 for a single small tool to £50,000 or more for a system a whole business runs on, with most small business projects landing between £3,000 and £25,000. Whether it is worth it comes down to one calculation: the annual cost of the manual work it removes, against the build cost plus running costs. This guide shows how to do that calculation before anybody quotes you.
By James 11 min read
What custom software costs in the UK
The honest answer is a range, because "custom software" describes everything from a form that writes to a spreadsheet to a platform running a business. What is useful is knowing which band you are in before you start talking to anyone.
Below £2,000 you are buying a single tool doing one job: a calculator, a form that feeds a system, an integration between two packages you already own. These are frequently the best value work available, because they are cheap and they remove a job somebody does every day.
Between £3,000 and £10,000 you get a genuine application for one area of the business: a booking system, a quoting tool, a job tracker, a customer portal. This is where most small business projects land and where the return is easiest to demonstrate.
Between £10,000 and £30,000 you get a system covering several connected areas: jobs, customers, quoting, invoicing and reporting joined up rather than separate. This is the band where a business stops using spreadsheets as infrastructure.
Above £30,000 you are building something a whole business runs on, usually replacing several systems, usually delivered in stages across six months or more.
UK custom software price bands
| Scope | Typical cost | Typical timescale |
|---|---|---|
| Single tool or integration | £500–£2,000 | 1–3 weeks |
| One business area (booking, quoting, job tracking) | £3,000–£10,000 | 4–10 weeks |
| Connected system across several areas | £10,000–£30,000 | 2–5 months |
| Platform the business runs on | £30,000+ | 6 months+, staged |
| Ongoing support and changes | 10–20% of build cost per year | Continuous |
| Hosting and running costs | £25–£150 per month | Continuous |
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The calculation that actually decides it
Take the job you want to remove. Work out how long it takes, how often it happens, and who does it. Multiply out to an annual figure, using a fully-loaded hourly cost for that person rather than their gross salary divided by 2,080.
Here is the example we use most often, because it is the most common one in the field. A trades business types a customer’s details at quote stage, again on the invoice, again into the accounts package and again into the VAT spreadsheet. Say four minutes a job, four times, on twelve jobs a week. That is roughly three and a quarter hours a week, or about 165 hours a year. At a loaded cost of £22 an hour, that is £3,600 a year of pure retyping.
Now add the second-order costs, which are usually larger and always ignored: the invoices that went out late because someone had a pile of job sheets, the jobs invoiced at the wrong price, the customer whose address was mistyped. In most businesses those exceed the direct time cost.
A build that removes it for £6,000 pays back in under two years on the direct saving alone, and considerably faster once the errors are counted. A build that costs £25,000 to remove the same job does not, and no amount of enthusiasm changes that.
When off-the-shelf honestly wins
Most of the time, and anyone who tells you otherwise is selling. Accounting, payroll, email, file storage and document management are all solved problems with mature products, and building your own would be an expensive way to get something worse.
Sector packages are usually the right answer too. If you are a dental practice, a lettings agency or a garage, there are products built for you by people who have spent twenty years learning the edge cases. Building something to compete with that is a bad use of money.
The honest test is whether your process is genuinely unusual or merely familiar. Plenty of businesses believe they work differently when they simply work the way they always have. If a package would fit with a modest change to how you do something, changing how you do it is nearly always cheaper than building software to preserve it.
Where building wins is the opposite case: the package almost fits but never quite does, you are paying per user forever for features nobody opens, the workaround has become somebody’s job, or the thing you need to join up is the gap between two systems that will never talk to each other.
That is the case we build for, custom software built around how you work.
We do the calculation before anyone quotes
The free process review maps how the work actually flows, puts hours against every repetitive job, and produces a written plan with a fixed quote. Some items come back marked as not worth building, which is the part that makes the rest of the document trustworthy.
What drives the price up
Integrations. Connecting to an accounts package with a good API is a day. Connecting to a twenty-year-old system with no API and a CSV export is a fortnight, and the difference is worth establishing early.
Users and permissions. "Everyone sees everything" is cheap. Role-based access with an approval chain is a real chunk of work and is frequently added late, which is the expensive way to add it.
Mobile. A responsive web application is included. A genuinely offline-capable mobile app, which is what field engineers with patchy signal actually need, is a separate piece of work.
Data migration. Bringing across five years of history from four spreadsheets with inconsistent formatting is often the single largest line in a project, and it is nearly always underestimated because it looks like a small job.
Reporting. One dashboard is straightforward. Configurable reporting that non-technical staff can build themselves is close to a product in its own right.
The costs after launch
Two ongoing costs, and neither should be a surprise. Hosting and running costs are usually £25 to £150 a month for a small business system, the same infrastructure that would host a busy website. Support and changes typically run at 10 to 20 per cent of the build cost per year, because businesses change and the software has to follow.
Budget for that from the start. A system nobody maintains becomes a system nobody trusts within about eighteen months, and at that point the original investment is written off rather than depreciated.
The thing you should not be paying is a per-user licence to use software you paid to have built. If a supplier proposes that, ask what happens to your access if you stop paying, and read the answer carefully.
How to get a quote you can rely on
Insist on a fixed price against a written scope, and be suspicious of a day rate with an estimate attached. The estimate is the supplier’s risk transferred to you.
Ask for staged delivery with something usable at the end of each stage. That protects you if the project stalls, and it means the saving starts arriving before the whole thing is finished.
Ask explicitly who owns the code and the data, and get the answer in the contract. The correct answer is that you do, with no licence that expires when the relationship does.
Finally, ask what the supplier thinks is not worth building. A supplier who says everything on your list is a good idea has not thought about your business; they have priced your list.
Why estimates move, and how to stop yours
Software estimates have a poor reputation for good reason: the thing being estimated is frequently not the thing that gets built. Requirements surface during the build that nobody could have stated at the start, because people describe how they think they work rather than how they actually do.
The fix is not better estimating. It is doing the discovery before quoting, in enough depth that the surprises happen while nothing is being paid for. That is what a process review is for, and it is why we do it free: a quote written from a genuine map of the work holds, and a quote written from a conversation does not.
The second protection is staged delivery with something usable at the end of each stage. If a project is going to overrun, you find out at the end of stage one rather than at the end of month five, and you have working software either way.
The third is a written scope with an explicit change process. Not to prevent changes, which are normal and often improvements, but so that a change is a priced decision rather than an argument about what was implied.
The costs of not building it
Every build-versus-buy calculation includes a third option nobody prices: carrying on. It is not free, and it is worth putting a number on it before deciding it is the cheap answer.
The direct cost is the hours, which the audit measures. The indirect costs are larger and reliably ignored: the errors that reach customers, the invoicing that lags because it depends on somebody sitting down with a pile of paperwork, and the work you turn down because the admin would not scale.
Then there is the concentration risk. In most businesses running on spreadsheets, one person understands how the whole arrangement fits together, and that person is a single point of failure with a holiday entitlement. Software does not remove that risk entirely, but it converts undocumented knowledge into something a second person can operate.
None of this means you should build. It means the comparison should be three-way, and that carrying on should carry a number rather than being treated as the zero option.
Frequently asked questions
If the answer is not here, ask us. You will get a straight one, from someone who does the work.
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How much does custom software cost in the UK?
From around £500 for a single small tool to £50,000 or more for a platform a whole business runs on. Most small business projects land between £3,000 and £25,000, with £3,000 to £10,000 covering a genuine application for one area such as booking, quoting or job tracking.
How do I work out whether custom software is worth it?
Take the manual job you want to remove, multiply time by frequency by a fully-loaded hourly cost to get an annual figure, then add the second-order costs: late invoices, pricing errors, mistyped details, which are usually larger. Compare that annual figure to the build cost plus running costs.
When is off-the-shelf software the better choice?
Most of the time. Accounting, payroll, email and file storage are solved problems, and mature sector packages usually beat anything you could build. The honest test is whether your process is genuinely unusual or merely familiar, if a package fits with a modest change to how you work, changing is cheaper than building.
What are the ongoing costs of custom software?
Hosting and running costs of roughly £25 to £150 a month for a small business system, plus support and changes at 10 to 20 per cent of the build cost per year. What you should not be paying is a per-user licence to use software you paid to have built.
What makes a custom software project more expensive?
Integrations with systems that have no proper API, role-based permissions added late, genuinely offline-capable mobile apps, data migration from inconsistent spreadsheets, and configurable reporting that non-technical staff can build themselves. Data migration is the one most often underestimated.
Should I get a fixed price or a day rate?
Fixed price against a written scope. A day rate with an estimate attached transfers the supplier’s risk to you. Ask for staged delivery with something usable at the end of each stage, so the saving starts arriving before the project finishes.
Who owns custom software once it is built?
You should, along with the data, with no licence that expires if the relationship does. Get it in the contract, and if a supplier proposes a per-user fee to use software you commissioned, ask precisely what happens to your access if you stop paying.
Why do software estimates move so much?
Because the thing being estimated is frequently not the thing that gets built. Requirements surface during the build because people describe how they think they work rather than how they actually do. The fix is discovery before quoting, deep enough that the surprises happen while nothing is being paid for.
What does it cost to carry on as we are?
More than most businesses have ever calculated. The direct cost is the hours; the indirect costs are the errors reaching customers, the invoicing that lags, and the work turned down because the admin would not scale. There is also the concentration risk of one person understanding how the whole arrangement fits together.