How to read the result
The headline figure is the development budget excluding VAT: what you pay for the product to exist. It says nothing about running costs, which appear just below it: yearly maintenance (15 to 25% of the initial budget, the usual ratio for software that keeps evolving) and monthly hosting for up to a thousand active users. Founders who only look at the first line tend to discover the other two six months after launch, exactly when cash is tightest.
The last line, the same scope with a traditional agency, applies a 900 to 1,400 EUR day rate to the same number of days. It is not a sales pitch: an agency that stacks a project manager, a designer and an architect sometimes adds real value on a very large project. For a SaaS under 50,000 EUR that chain is rarely needed, which is the subject of our comparison agency or freelancer for SaaS development.
The grid behind the calculator
These are the durations per building block, in senior developer days. They are the orders of magnitude I use to prepare my own quotes, with a modern stack (TypeScript, Astro or Next.js, Postgres, Cloudflare) and proven components rather than code rewritten for every project.
| Building block | Days |
|---|---|
| MVP foundation (scoping, architecture, deployment, core feature) | 10 |
| Sellable V1 foundation | 25 |
| Multi-tenant platform foundation | 45 |
| User accounts and roles | 2 |
| Stripe subscriptions (trials, upgrades, invoices, webhooks) | 4 |
| Organisations, teams, invitations | 6 |
| Dashboard and analytics | 4 |
| Admin back office | 4 |
| Transactional emails and notifications | 2 |
| Documented public API | 6 |
| AI feature (Claude, GPT, RAG) | 8 |
| CSV or Excel import and export | 2 |
| Multilingual interface | 3 |
| Installable mobile version (PWA) | 5 |
| Per third-party integration (CRM, ERP, accounting) | 3 |
| Custom design with a UI designer | 8 |
Three factors are then applied. Business complexity multiplies the total by 1.2 (medium) or 1.45 (high): this is what turns a 15,000 EUR quote into a 40,000 EUR one, because a pricing rule with exceptions or a multi-level approval workflow costs more than any screen. Sensitive data adds 15% for logging, encryption and security review, in line with the GDPR article 32 security requirements. Finally, the range goes from -10% to +15% on days, because software projects overrun more often than they finish early.
What the calculation does not cover
The calculator prices development, not operations. Payment fees are listed on Stripe's pricing page, and AI model usage is billed per token, see Anthropic's pricing or OpenAI's. On a well-designed AI feature this line stays modest, but it grows with your users: our guide to AI integration costs walks through the maths.
It does not cover copywriting, legal terms or launch marketing either. Those are real costs, often underestimated, that are not a developer's job.
Three honest ways to bring the number down
The first is to untick boxes. Every feature removed from an MVP is a month of runway saved, and most "must-have" features only matter after the first hundred customers. The public API, multilingual support and the mobile app are the three boxes that most often wait without harm. Our article on MVP mistakes to avoid covers this in depth.
The second is to lower complexity rather than screen count: a simplified business rule for V1, with edge cases handled manually, costs a fraction of full automation. The third is public funding where it exists; in France, the Innovation Tax Credit refunds 20% of eligible SME spending.
What next?
If the range fits your budget, the calculator button opens the contact form with your configuration already filled in. I answer within one business day with the questions that turn the range into a firm quote. For prices by SaaS type, read the full guide on SaaS development cost in 2026, or see our custom SaaS development offer.
Frequently asked questions
Is the calculator result a quote?
No. It is an indicative range computed from a senior day rate of 550 to 750 EUR excl. VAT and typical durations per feature. A firm quote needs a 30-minute scoping call, because two products with the same boxes ticked can have very different business rules.
Why is the range so wide?
The low end assumes a stable scope and a 550 EUR day rate; the high end adds 15% contingency and a 750 EUR day rate. Narrowing it requires information the calculator cannot have: mockups, calculation rules, data volumes, existing tools to connect.
Are Stripe fees and AI API costs included?
No. The calculator prices development. Stripe fees, AI API usage (billed per token by Anthropic or OpenAI) and third-party subscriptions are running costs that grow with usage and belong in your monthly budget.
How is the timeline calculated?
It assumes one senior developer delivering 4 to 4.5 days of effective work per week, the rest going to meetings, acceptance testing and the unexpected. A project split into two-week sprints with regular reviews holds its timeline far better than one delivered in a single block.
Can part of the budget be funded?
For French companies, the Innovation Tax Credit (CII) refunds 20% of eligible SME spending since 2025, and Bpifrance offers innovation grants and loans. Other countries have equivalents. These schemes take months to process, so plan them before development starts.