The verdict in three sentences
In-housing a developer makes sense with continuous load and a dense roadmap: a dedicated employee costs 70,000 to 95,000 EUR loaded/year but builds up domain knowledge. Outsourcing to an agency turns a fixed cost into a variable one, avoids the 3-6 month time-to-hire and removes the bus factor of a single developer. Below ~60 % real load, outsourcing stays cheaper and more flexible.
The real cost of an in-house developer
Gross salary is only the visible part. Employer charges, equipment, training and management inflate the real cost by 45 to 60 % above gross. Here are the 2026 orders of magnitude for a senior dev in France.
| Line item (annual) | 2026 range |
|---|---|
| Senior gross salary | 48,000-62,000 EUR |
| Employer charges (~42 %) | 20,000-26,000 EUR |
| Equipment + licences | 2,000-4,000 EUR |
| Training | 1,500-3,000 EUR |
| Recruitment (amortised) | 3,000-6,000 EUR |
| Total loaded cost | 74,500-101,000 EUR |
Add time-to-hire: 3 to 6 months to recruit a senior profile, during which the project stalls. The agency, by contrast, starts in 2 to 4 weeks.
3-year cost by real load
The decisive question: how many development days do you really consume per year? We compare in-house (85,000 EUR loaded) to an agency retainer at 600 EUR/day across three load levels.
| Annual load | In-house (3 years) | Agency (3 years) | Winner |
|---|---|---|---|
| 80 days/year | 255,000 EUR | 144,000 EUR | Agency |
| 130 days/year | 255,000 EUR | 234,000 EUR | Agency |
| 160 days/year | 255,000 EUR | 288,000 EUR | In-house |
| 200 days/year | 255,000 EUR | 360,000 EUR | In-house |
The tipping point sits around 140-150 real load days per year. Below that, the agency wins clearly because you only pay for what you use. Above it, a dedicated in-house dev becomes more cost-effective and builds knowledge.
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Mini case study
Herve, CEO of an SME in Toulouse, is considering hiring a developer for his website and internal tools. His real need: around 90 dev days/year, in irregular peaks. A senior would cost him 85,000 EUR loaded/year, i.e. 255,000 EUR over 3 years, plus 4 unproductive recruitment months. An agency at 600 EUR/day for 90 days comes to 54,000 EUR/year, i.e. 162,000 EUR over 3 years, with no bus factor or HR management. He saves 93,000 EUR over 3 years and keeps the flexibility to scale load up or down. He outsources, ready to in-house later if load exceeds 150 days/year.
FAQ
What is the real cost of an in-house developer? Budget 74,500 to 101,000 EUR loaded/year for a senior in France, i.e. 45 to 60 % above gross salary once charges, equipment and training are included.
What is the bus factor? It is the risk that a single developer holds all the knowledge: if they leave or fall ill, the project stops. An agency spreads that risk across a team.
Above what load should you in-house? Around 140-150 real development days per year. Below, the agency is cheaper; above, in-house becomes cost-effective.
Can you combine in-house and agency? Yes, it is common: an internal tech lead drives vision and roadmap, the agency absorbs load peaks and occasional specialist skills.
How long to recruit a senior dev? 3 to 6 months from posting to real productivity, versus 2 to 4 weeks to start with an agency.
Let's scope your project. Estimate your annual dev load and roadmap: we model in-house vs agency over 3 years and tell you where your tipping point lies. 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.
