What Does Custom Software Cost?

Short Answer

Custom software in the UK typically costs between £15,000 and £150,000+, with most small business systems landing in the £25,000 to £60,000 range and larger multi-role platforms running well above that. The price is driven by scope, integration count, and complexity of the data model — not by the agency’s hourly rate alone. A simple internal tool with one user role and no integrations might be £15k; a client portal with billing, role permissions, and three third-party integrations is usually £40k to £80k; a multi-tenant SaaS platform with custom reporting and a public-facing app is six figures.

What You Are Actually Paying For

Software pricing surprises people because the cost is not in the visible parts. A login screen looks simple but sits on top of authentication, password reset flows, account lockouts, session management, and security hardening. A dashboard “just shows numbers” but requires a data pipeline, caching strategy, role-based filtering, and export tooling. Roughly half of a project’s cost is the invisible scaffolding — the parts the user never thinks about but that have to exist for the visible parts to work.

The four cost drivers we see consistently are scope (how many distinct screens and user flows), integrations (each third-party API adds discovery, authentication, error handling, and ongoing maintenance), data complexity (a flat list of records is cheap; a relational model with permissions, audit trails, and conditional logic is not), and non-functional requirements (uptime targets, security standards, accessibility compliance, performance). Two systems that look identical from the outside can differ by 3x in cost based on these factors alone.

A useful rule of thumb: a system that replaces a single spreadsheet for one team usually costs £15k to £30k. A system that replaces three or four tools and serves multiple roles usually costs £40k to £80k. A system that becomes the operational backbone of the business — used daily by every team — almost always crosses £80k and runs higher with reporting and integration work.

Why the Price Range Is So Wide

The honest answer is that “custom software” is not one product. A £20,000 project and a £200,000 project are not the same thing built bigger — they are categorically different in scope, depth, and risk. Asking what custom software costs without scope is like asking what a building costs: a garden shed and a warehouse are both buildings, but the answer depends entirely on what you need.

Budget conversations work best when they start from outcomes rather than features. “We need to replace the spreadsheet our four-person ops team uses to manage client work” leads to a meaningful estimate. “We want an app” does not.

What to Look For

• Fixed scope with a fixed price, or time and materials with a clear cap. Either model can work; what does not work is open-ended billing on an open-ended scope.
• Discovery phase priced separately. A short paid discovery (1 to 2 weeks) gives both sides the information to commit to a build price honestly. Agencies that skip discovery and quote on a vague brief are gambling, and the gamble usually lands on the client.
• Ongoing costs named upfront. Hosting, third-party API fees, SSL certificates, monitoring, and support retainer should all be on the table from the start. A £40k build with £400/month of running costs is very different from one with £4,000/month.
• What is and is not included. Branding, content writing, user training, data migration from old systems, and post-launch changes are all things that either need to be in the price or named as separate line items.

Common Mistakes

The biggest mistake is choosing on price alone. A £20k quote and a £40k quote for “the same project” are almost never the same project — one of them is missing something the other has factored in, and the gap shows up after kick-off as scope changes, change requests, or quality issues. The second mistake is under-budgeting for the year after launch. Software needs hosting, maintenance, security updates, and improvements; budgeting 15 to 25% of the build cost annually is more realistic than zero.

How We Approach This

We quote in two stages — a fixed-price discovery to lock scope, then a fixed-price build estimate based on what discovery produced. This keeps the build price honest and removes the gamble from both sides.

Get a Realistic Estimate

The services and systems pages below outline what we build and the typical ranges we work in. If you have a brief and want a grounded price conversation, that is the place to start.