The verdict in three sentences
When 12 Excel VBA workbooks run a plant's production planning and only one person can maintain them, the real risk is not technical: it is planning grinding to a halt the day that person leaves. Migrating to a web application costs EUR 30,000 to 60,000 excl. VAT, preceded by an audit of EUR 4,000 to 7,000, over 4 to 6 months. The cost of one week of blind planning often exceeds the project budget.
Why VBA workbooks become a risk in 2026
Macro-enabled Excel files often carry fifteen years of history. They work, but they pile up weaknesses.
| Weakness | Typical situation | Estimated impact (2026) |
|---|---|---|
| Single-person dependency | 1 in-house developer, no documentation | Replacement: 3 to 6 months of hiring and handover |
| Concurrent access | One user at a time, locked files | 30 to 60 min lost per planner per day |
| No history | Overwritten versions, "v3_final_bis" copies | Untraceable planning errors |
| Blocked macros | Microsoft blocks internet macros by default since 2022 | Workstations to reconfigure, security risks |
| File size | Workbooks of 40 to 120 MB | 2 to 10 min recalculations, crashes |
| Cross-file links | External formulas to 11 other workbooks | One change breaks the chain |
The departure risk is easy to quantify: if planning stops for a week and causes a 2% delivery slip on weekly revenue of EUR 1.2M, the impact exceeds EUR 24,000, before customer penalties.
The cost of a migration in 2026, step by step
| Step | Scope | Budget excl. VAT | Lead time |
|---|---|---|---|
| Audit and mapping | Inventory of the 12 workbooks, flows, calculation rules, users | EUR 4,000 to 7,000 | 2 to 3 weeks |
| Design | Data model, screen mock-ups, prioritisation | EUR 4,000 to 8,000 | 3 weeks |
| Core development | Planning, business calculations, role-based access | EUR 15,000 to 30,000 | 8 to 12 weeks |
| Data migration | Cleaning, import of Excel history | EUR 3,000 to 7,000 | 2 to 3 weeks |
| Multi-user and history | Concurrent access, change log, versions | EUR 3,000 to 6,000 | 2 weeks |
| ERP connector and exports | ERP link, Excel export kept for analysis | EUR 3,000 to 7,000 | 2 to 3 weeks |
| Parallel run | Both systems run for 3 to 4 weeks | EUR 2,000 to 4,000 | 3 to 4 weeks |
Total: EUR 34,000 to 67,000 excl. VAT including the audit, over 4 to 6 months. Hosting and maintenance: EUR 400 to 900 a month depending on support level.
Migration risks and how to reduce them
| Risk | Likelihood without method | Mitigation |
|---|---|---|
| Forgotten business rules | High | Line-by-line macro audit, test sets built from real plans |
| User rejection | Medium | Screens close to Excel ergonomics, Excel export kept |
| Results differ from Excel | High | 3 to 4 week parallel run with automatic comparison |
| Budget overrun | Medium | Delivery in releases, fixed price per release |
| Production disruption | Low | Weekend cutover, rollback possible for 1 month |
The key is the parallel run: until the application produces the same results as the workbooks over 3 to 4 real weeks, Excel stays the reference.
Mini case study
Rachel, financial controller at a metalworking manufacturer in Manchester (180 staff), depends on 12 workbooks maintained by a technician close to retirement. She approves a EUR 5,500 audit and then a EUR 46,000 application, i.e. EUR 51,500.
Need a professional website?
Kolonell builds websites that attract clients, optimized for the Sénégalese market. Free quote in 2 minutes.
Her 4 planners lose an average of 45 minutes a day on file locks and recalculations: 4 × 0.75 h × 220 days × EUR 45 loaded cost = EUR 29,700 a year. The project pays back in about 21 months on that time saving alone, and the stoppage risk tied to the technician's departure, estimated at more than EUR 24,000 per week, disappears.
FAQ
How much does it cost to migrate an Excel VBA tool to a web app?
Between EUR 30,000 and 60,000 excl. VAT for the application in 2026, plus EUR 4,000 to 7,000 for the audit. A single simple workbook can be migrated for EUR 8,000 to 15,000.
Can we keep Excel for analysis?
Yes. The application keeps Excel exports and sometimes a Power Query connection, so teams keep their pivot tables without touching source data.
How long does the project take?
Allow 4 to 6 months, including 3 to 4 weeks of parallel running. A first useful module goes live after 8 to 10 weeks.
What if our VBA developer leaves before the end?
The initial audit documents every macro within the first 2 to 3 weeks. Even if they leave, the business rules are written down and tested.
Should we migrate all 12 workbooks at once?
No, we prioritise the 2 or 3 most critical ones, which often carry 70% of the value. The others follow in 6 to 10 week releases.
Let's scope your project. Send us the list of your workbooks and the number of users: we will price the audit and a phased migration between EUR 30,000 and 60,000 over 4 to 6 months. 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.
