Custom Software Development Cost UK: Calculator + 2026 Guide

One of the first questions every business asks when considering custom software is: how much is this going to cost? It's a fair question, and one that deserves a straight answer, not the usual "it depends" non-answer you get from most agencies.

We've delivered over 100 software projects for UK businesses, universities, and startups over the past 15 years. In this guide, we'll share real pricing data, explain what drives cost, and give you a framework for budgeting your project accurately.

The short answer: custom software development in the UK typically costs between £15,000 and £500,000+, depending on complexity, team composition, and timeline. But that range is nearly useless without context, so let's get specific.

Two ways to use this page. If you want your own number now, the calculator below works it out from your scope in about a minute. If you want to understand what drives the figure before you trust it, keep reading — everything the calculator does is explained underneath, rate by rate.

Work out the cost of your project

A published range is the answer to nobody's question. Tell it what you are building and what it has to do, and you get a costed range for that: effort in person-days, a blended UK day rate, a realistic timeline, and what it costs to keep running once it is live. No email, and the result has a link you can send to whoever signs it off.

What this number is, and isn't

It is a budgeting figure built from the same day rates and effort assumptions we use to quote real work. It is not a quote. The single biggest source of error is scope you have not thought of yet, and it moves the number up, never down.

If the number changes the question

Not sure this should be built at all — that is a fractional CTO conversation.
It was already built and went wrong — rescuing costs less than rebuilding.

Why Custom Software Costs What It Does

Before we get to numbers, it's worth understanding the main cost drivers. Software pricing isn't arbitrary. It reflects real constraints.

UK developer day rates typically run £400–£850 per day for senior engineers, depending on specialisation. AI/ML engineers command a premium, often £600–£1,000/day. Project managers, designers, QA engineers, and DevOps specialists add further cost.

The big factors that determine your total bill:

Scope and feature complexity: a simple internal tool vs. a consumer marketplace are orders of magnitude apart
Number of integrations: connecting to third-party APIs, payment providers, CRMs, and ERPs each add time
Security and compliance requirements: healthcare (NHS/GDPR), financial services (FCA), and education projects have significant compliance overhead
Device targets: web only is cheapest; adding native iOS + Android roughly doubles frontend cost
Team size and seniority: more senior engineers cost more per day but ship faster
Location of team: London-based teams command a premium over nearshore/offshore

Custom Software Cost by Project Type

Here are realistic cost ranges based on our experience across different project types.

MVPs and Proof-of-Concept Projects

£15,000 – £60,000 | 6–16 weeks

An MVP (minimum viable product) is a stripped-down version of your idea with enough features to validate the concept with real users. These projects are scoped tightly. We're not building the final product, we're building the version that proves the market exists.

What you get at this tier: core user flows, basic authentication, a database, one or two integrations (e.g. Stripe for payments, SendGrid for email), and a deployment pipeline.

What you don't get: admin panels, advanced analytics, sophisticated permission systems, or production-grade scaling. Those come in phase two.

Prodevel's Startup Accelerator packages start at £15,000 for a 6-week MVP sprint, including design, development, testing, and deployment.

Get in touch

Internal Business Tools and Dashboards

£20,000 – £80,000 | 8–20 weeks

Internal tools, such as reporting dashboards, CRM customisations, workflow automation, and admin portals, are often the highest-ROI software projects because they directly reduce labour costs or eliminate manual errors.

A good example: we built a university admissions management system for LSHTM that automated a process taking 25+ hours per week. Total project cost: ~£45,000. Annual time savings: approximately £60,000 of staff time. ROI: positive within the first year.

At this tier you'd expect: user authentication and roles, data visualisation, integrations with existing systems (e.g. your ERP or CRM), export functionality, and a mobile-responsive UI.

Customer-Facing Web Applications

£40,000 – £150,000 | 12–30 weeks

Customer-facing apps, such as booking systems, e-commerce platforms, SaaS products, and client portals, carry higher stakes than internal tools. Performance, security, and user experience all matter more when paying customers are involved.

At this tier: polished UI/UX design, payment processing, user accounts and profiles, notifications, search and filtering, content management, and usually a marketing landing page to go with it.

Complexity jumps significantly when you add: marketplace functionality (two-sided networks), real-time features (chat, live updates), subscription billing, or multi-tenancy (your app serves multiple separate organisations).

Mobile Applications (iOS & Android)

£35,000 – £120,000 | 10–24 weeks

Mobile apps are costed separately because the platform adds complexity. A React Native or Flutter app (cross-platform) is typically 30–40% cheaper than building separate native iOS (Swift) and Android (Kotlin) apps.

For most business apps, cross-platform is the right choice. Native development makes sense when you need deep hardware access (AR, Bluetooth, background processing) or when performance is critical (gaming, real-time trading).

Approach	Cost Range	Timeline	Best For
React Native / Flutter	£35k – £80k	10–20 weeks	Most business apps, content apps
Native iOS only	£40k – £90k	12–22 weeks	iOS-first B2C apps
Native Android only	£35k – £85k	10–20 weeks	Android-first markets
Native iOS + Android	£70k – £150k	18–30 weeks	Consumer apps needing peak performance

Enterprise and Platform Projects

£100,000 – £500,000+ | 6–18 months

Large-scale enterprise software, such as ERP systems, complex multi-tenant SaaS platforms, data pipelines, and AI-powered products, sits in a different category entirely. These projects require careful architecture, dedicated teams, and extended timelines.

At this tier you're typically talking about: multiple user roles and permission systems, complex business logic, integrations with 5+ external systems, data warehousing or analytics, robust security and audit trails, and ongoing infrastructure management.

The cost isn't just the build. It includes architecture design, code review, documentation, security audits, load testing, and a structured handoff if the client is taking over maintenance.

AI and Machine Learning Projects

£25,000 – £200,000+ depending on scope

AI projects are particularly hard to estimate because the cost depends on whether you're:

Using existing AI APIs (OpenAI, Claude, Google Gemini): cheapest and fastest, but less customisation
Fine-tuning an existing open-source model (Llama, Mistral) on your data: moderate cost, high customisation
Training a model from scratch: expensive, only justified for unique datasets or edge deployments

Most UK business AI projects fall into category 1 or 2. A document processing AI using GPT-4 with RAG (retrieval-augmented generation) might cost £25,000–£60,000 to build and deploy. A custom-trained NLP model for a specific industry vertical might run £80,000–£150,000.

The ongoing costs also matter: API usage fees (typically £200–£2,000/month for mid-scale usage), compute costs for model hosting, and monitoring/retraining as your data evolves.

UK Agency vs. Freelancer vs. Offshore: Cost Comparison

Many businesses consider freelancers or offshore teams as a way to reduce costs. The comparison is more nuanced than day-rate arithmetic.

Option	Day Rate Range	Typical Project Cost	Risk Level
UK-based agency	£450–£900/day	Full market rate	Low
UK freelancer(s)	£350–£750/day	10–20% saving	Medium
Nearshore (Eastern Europe)	£150–£350/day	30–50% saving	Medium
Offshore (India, Southeast Asia)	£50–£150/day	60–75% saving	High

The risk for lower-cost options isn't primarily about code quality. Plenty of offshore teams produce excellent code. The risk is communication overhead, timezone friction, misunderstood requirements, and the difficulty of course-correcting mid-project when something isn't working.

For projects under £30,000, a good senior freelancer is often the best value. For complex projects requiring coordination across design, development, QA, and infrastructure, an agency structure typically pays for itself in time saved.

Hidden Costs to Budget For

The quoted project cost is rarely the true total cost. Budget for these additional items:

Infrastructure and hosting: £50–£500/month on AWS/GCP/Azure depending on scale
Domain and SSL: £20–£100/year
Third-party services: payment processing (Stripe: 1.4% + 20p per EU card transaction), email (£20–£200/month), authentication, monitoring
Maintenance and updates: typically 15–20% of original build cost per year
Security audits: £5,000–£20,000 for a proper penetration test
App store fees: £25 one-off (Android), £99/year (iOS)
Legal: GDPR data processing agreements and terms of service, with £2,000–£5,000 budgeted for a solicitor review

How to Get an Accurate Quote

The more detail you can provide upfront, the more accurate your quote will be. When approaching a development agency, prepare:

A brief (1–2 pages) describing the problem you're solving and who the users are
A list of must-have features (Phase 1) vs. nice-to-have features (Phase 2+)
Any existing systems the software needs to connect to
Your target launch date and hard deadlines
Your budget range, since agencies appreciate transparency and can scope accordingly
Examples of products or features you like (screenshots, app store links)

The best agencies will push back on scope, ask hard questions about your users, and suggest alternatives you haven't considered. Be wary of agencies that say yes to everything in a first meeting. They're either guessing or planning to expand scope later.

What a Good Software Investment Looks Like

The best way to evaluate cost is in relation to return. Consider three frameworks:

Labour displacement: If your software automates a task that currently costs £X per year in staff time, and the software costs £Y to build, the payback period is Y/X years.

Revenue enablement: If the software enables a new product or service line, what's the conservative annual revenue potential? A £50,000 investment that enables £200,000 of new annual revenue is a good investment regardless of absolute cost.

Competitive parity: In some industries, not having a certain type of software means losing deals to competitors who do. The cost of not building can be higher than the cost of building.

Want a specific estimate for your project? Run your scope through the calculator for a costed range in a minute, or book a free 30-minute scoping call and we'll pressure-test it with you. No obligation, no sales pitch.

Open the cost calculator

Summary: UK Custom Software Development Costs at a Glance

Project Type	Budget Range	Timeline
MVP / Proof of Concept	£15,000 – £60,000	6–16 weeks
Internal Tool / Dashboard	£20,000 – £80,000	8–20 weeks
Customer-Facing Web App	£40,000 – £150,000	12–30 weeks
Mobile App (Cross-Platform)	£35,000 – £80,000	10–20 weeks
Mobile App (Native iOS+Android)	£70,000 – £150,000	18–30 weeks
AI / ML Solution	£25,000 – £200,000+	8–24 weeks
Enterprise Platform	£100,000 – £500,000+	6–18 months

Those are bands, not budgets. Two projects in the same row of that table routinely differ by a factor of three, because one needs multi-tenancy and an FCA audit trail and the other does not.

Turn the band into a number. The calculator applies these same rates to your scope and shows the working — where every person-day goes, and what the first year costs, not just the build.

Calculate your project cost

The most important thing is to work with an agency that will tell you when your budget is unrealistic for your scope, then help you find a way to get the highest-value version of your idea built within your constraints. That's the conversation we have with every client.