Typical ranges
| Project | Range | Duration |
|---|---|---|
| Small internal tool | £8,000–£15,000 | 6–10 weeks |
| Business application, several workflows | £18,000–£45,000 | 12–20 weeks |
| Customer portal on existing data | £12,000–£28,000 | 8–14 weeks |
| Application with AI capability | £20,000–£50,000 | 14–22 weeks |
What moves the price
- Integrations — each system, and whether it has an API
- Business rule complexity — pricing, approvals, calculations with exceptions
- Data migration from whatever you use now
- Permission complexity
- Reporting, which is consistently underestimated
Screen count is a poor proxy for effort. Twenty similar screens is a template; one screen implementing eight interacting rules is a fortnight.
What should be included
- Tests around the business rules and permissions
- A deployment process and a staging environment
- Monitoring and alerting
- Documentation and handover
- The code, in a repository you own
Running and maintenance
Hosting for a typical business application is £40–£200 a month. Maintenance is 15–25% of build annually, covering dependency updates, Django upgrades and small changes.
Budget it explicitly. Unmaintained applications become progressively more expensive to change, which is how a rewrite proposal eventually appears.
Start with one workflow
Building one workflow properly, in production, in eight weeks tells you far more than a complete specification does — and it produces a much better estimate for the rest.
It also means that if something is wrong, you find out early and cheaply.