The verdict in three sentences
A CTO who invites 4 suppliers to bid without a structured requirements document gets quotes that vary by a factor of three, because each one prices a different scope. A 15 to 25-page document, with MoSCoW-prioritised user stories and measurable non-functional requirements, narrows the spread from ±60% to ±20%. A facilitated write-up takes 3 to 6 days (3,000 to 6,000 EUR in France), while an Edinburgh discovery sprint runs 8,000 to 15,000 GBP and adds prototypes.
The template CTOs expect
Edinburgh CTOs, often from fintech, public sector suppliers or life sciences, want a document they can compare across bidders. Here is the structure that works in 2026.
| Section | Expected content | Pages | Common mistake |
|---|---|---|---|
| Context and goals | Business stakes, quantified success metrics | 2 | Vague goals with no KPI |
| Scope and actors | Users, roles, volumes (e.g. 120 users, 8,000 contracts) | 2 to 3 | Volumes left out |
| MoSCoW user stories | 30 to 60 stories, Must, Should, Could, Won't | 6 to 10 | Everything marked Must |
| Non-functional requirements | 99.5% availability, response < 2 s, UK GDPR, WCAG 2.2 AA | 2 to 3 | Not quantified |
| Integrations | ERP, Azure AD SSO, document management, e-signature | 1 to 2 | Undocumented APIs |
| Data migration | Sources, volumes, quality, owner | 1 | Ignored, then billed |
| Response format | Scoring grid, quote format, schedule | 1 to 2 | Free format, incomparable quotes |
The most useful deliverable is the mandatory response grid: every supplier prices the same work packages, story by story, so quotes can be compared line by line.
Written requirements vs discovery sprint
Impact shows in the spread of offers, the length of the procurement and change requests during delivery.
| Indicator | No requirements | Structured requirements | Discovery sprint (Edinburgh) |
|---|---|---|---|
| Spread of quotes | ±60% around the mean | ±20% | ±15% |
| Procurement duration | 8 to 10 weeks | 4 to 5 weeks | 5 to 6 weeks incl. sprint |
| Supplier questions | 40 to 60 | 10 to 15 | 5 to 10 |
| Change requests during project | 15 to 30% of budget | 5 to 10% | 5 to 8% |
| Cost | 0 | 3,000 to 6,000 EUR (approx. 2,600 to 5,200 GBP) | 8,000 to 15,000 GBP |
| Duration | Not applicable | 3 to 6 days | 2 to 3 weeks |
Non-functional requirements often account for 20 to 30% of the budget. 99.5% availability tolerates about 3 h 40 min of downtime a month; demanding 99.9% cuts that to 44 minutes and can double hosting and on-call costs.
Mini case study
Callum, CTO of a distribution group in Edinburgh, must invite 4 suppliers to bid on a supplier contract management app (150 users, 6,000 active contracts).
- First round without a document: quotes from 60,000 to 150,000 GBP, impossible to compare.
- Facilitated requirements: 4 days, 4,200 GBP, 42 user stories including 24 Musts.
- Second round: quotes from 88,000 to 112,000 GBP, a ±12% spread around 100,000 GBP.
- Expected change requests: 7% instead of the 22% seen on the previous project, about 15,000 GBP avoided.
- Outcome: 4,200 GBP invested for roughly 15,000 GBP of avoided change requests and a month saved. A discovery sprint at 12,000 GBP would have added clickable prototypes, useful only if the UX is uncertain.
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FAQ
How long should a web application requirements document be?
15 to 25 pages for a project of 50,000 to 200,000 GBP. Beyond 40 pages, suppliers skim and ambiguities return.
Should we enforce MoSCoW prioritisation?
Yes, and keep Musts to about 60% of stories. That is what makes a first release deliverable in 3 to 4 months.
Requirements document or discovery sprint?
A document (3 to 6 days) is enough when the process is well known. A discovery sprint at 8,000 to 15,000 GBP pays off when the user journey or data model is still unclear.
Should the budget appear in the document?
An indicative range (for example 90,000 to 120,000 GBP) improves the relevance of answers. Without it, 1 bid in 4 often lands outside the frame.
Which UK GDPR requirements should be written down?
Hosting location, retention periods, access logging and right to erasure. Each must be testable during acceptance.
Let's scope your project. Share your application need and constraints, and we will frame the requirements in 3 to 6 days with user stories, quantified requirements and an indicative budget. Detailed quote within 48 h. WhatsApp +221 77 596 93 33.
Mohamed Bah
Fondateur, Kolonell
Passionate about digital and entrepreneurship in Africa, Mohamed has been helping Sénégalese businesses with their digital transformation since 2020. Founder of Kolonell, he believes every SME deserves a professional and accessible online présence.
