The verdict in three sentences
An SLA (Service Level Agreement) turns a vague availability promise into a quantified commitment with penalties: 99.9% isn't "always online," it's 8.7 hours of tolerated downtime per year. In 2026, moving from shared hosting to a high-availability setup costs 30 to 100 EUR/month more, monitoring included. The right level is calculated on the real cost of an hour of downtime for your business, not on a marketing number.
Understanding availability levels
Each extra "nine" drastically cuts tolerated downtime — and raises the cost.
| SLA level | Downtime/year | Downtime/month | Typical use |
|---|---|---|---|
| 99% | 3.65 days | 7.2 h | Low-criticality brochure site |
| 99.9% | 8.77 h | 43 min | Lead-generating B2B site |
| 99.95% | 4.38 h | 22 min | E-commerce, client area |
| 99.99% | 52.6 min | 4.3 min | Critical application, SaaS |
| 99.999% | 5.26 min | 26 s | Ultra-critical infra (rare) |
For a B2B brochure site, 99.9% is the right compromise. Aiming for 99.99% multiplies infrastructure costs with no proportional benefit for most sites.
What makes up a serious SLA
An SLA isn't just a percentage. These clauses separate a real commitment from a sales pitch.
| Clause | What it guarantees | To negotiate |
|---|---|---|
| Availability rate | Monthly/annual uptime | 99.9% minimum |
| Penalties | Credit if not met | 5-30% of the monthly fee |
| Resolution time | Guaranteed restore delay | 4 h for blocking incidents |
| Monitoring | Surveillance and alerts | 24/7, external probes |
| Exclusions | Planned maintenance, force majeure | Cap the maintenance window |
| Reporting | Monthly uptime report | Transparent, third-party measured |
An SLA with no quantified penalty is worthless: the penalty is what aligns the host's interest with yours.
The cost of downtime and the high-availability premium
The right SLA level is justified by the cost of an outage. Here's how to compare it to the premium.
| Item | 2026 order of magnitude |
|---|---|
| Standard shared hosting | 10 – 30 EUR/month |
| High-availability hosting (redundancy) | +30 – 100 EUR/month |
| 24/7 monitoring + on-call | 30 – 150 EUR/month |
| CDN + anti-DDoS protection | 20 – 80 EUR/month |
| Cost of 1 h downtime (lead site) | 200 – 2,000 EUR in lost leads |
If one hour of downtime costs you 1,000 EUR in lost leads, paying 80 EUR/month to cut annual downtime from 8.7 h to under 1 h pays off with the first prevented incident.
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Mini case study
Julien, head of a B2B consulting firm in Lyon, generated 60% of his leads through his site. On shared hosting with no SLA, a 6-hour outage on a Tuesday morning made him miss about ten contact requests, estimated at 1,800 EUR in lost opportunities. He migrates to a 99.9% high-availability setup: a 75 EUR/month premium, i.e. 900 EUR/year, 24/7 monitoring included, with a 20% monthly-fee penalty for breaches. A single prevented outage repays two years of premium — the decision was obvious.
FAQ
What does 99.9% actually mean?
It allows 8.77 cumulative hours of downtime per year, about 43 minutes per month. It's not "never down," it's a measured threshold beyond which penalties apply.
Does an SLA guarantee my site will never go down?
No, no SLA guarantees zero downtime. It guarantees a minimum rate and a resolution time, with compensation if the host misses its commitments. It's a reinforced best-efforts commitment, not a miracle.
Do penalties refund my real loss?
Rarely in full: they're often capped at a percentage of the monthly fee (5 to 30%). Their purpose is to push the host to honor the commitment, not to cover your lost revenue. Hence the importance of choosing the right level upfront.
Do I really need high availability for a brochure site?
Only if your site is critical to your sales or image. For a low-lead brochure site, 99% is enough. As soon as the site carries leads or a client area, aim for 99.9%.
What is redundancy and why does it cost more?
Redundancy duplicates components (servers, databases, network) so a single failure doesn't stop the service. That doubles part of the infrastructure, hence the 30 to 100 EUR/month premium, but it's what enables 99.9% and beyond.
Let's scope your project. Tell us how critical your site is and the estimated cost of an hour of downtime: we'll scope the right SLA level and matching infrastructure, without over-provisioning. 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.
