The verdict in three sentences
The multi-tenant choice is the most structural architecture decision of your SaaS: it sets 30 to 40% of your run cost over two years. A shared database costs 200 to 600 EUR/month but complicates isolation; a database per tenant offers strong isolation at 800-2,500 EUR/month. In 2026, most B2B SaaS start on a shared database with logical partitioning, reserving physical isolation for demanding enterprise accounts.
The three models and their run cost
There are three main isolation families, from cheapest to most isolated. 2026 benchmarks for a SaaS with 50 active tenants.
| Model | 2026 run /month | Isolation | Scaling cost | Compliance |
|---|---|---|---|---|
| Shared database (tenant_id column) | 200 - 600 EUR | Logical | Low, pooled | Fine with RLS |
| Schema per tenant | 500 - 1,200 EUR | Medium | Medium | Good |
| Database per tenant | 800 - 2,500 EUR | Strong | High | Excellent |
| Hybrid (pool + isolated VIP) | 600 - 1,800 EUR | Variable | Controlled | Very good |
The shared database pools everything and stays unbeatable on cost as long as your volumes are homogeneous. As soon as one client weighs 10x more than the others, or requires data localization, the hybrid model becomes the right compromise: pooled by default, isolation on demand for premium accounts.
What each choice really costs over 2 years
Cost is not just the server. You must factor in initial development, security and operations. 2026 estimate for a SaaS scaling from 10 to 100 tenants.
| Line item | Shared DB | Schema/tenant | DB/tenant |
|---|---|---|---|
| Initial isolation dev | 6,000 - 12,000 EUR | 12,000 - 25,000 EUR | 20,000 - 40,000 EUR |
| Cumulative 24-mo run | 6,000 - 14,000 EUR | 14,000 - 30,000 EUR | 25,000 - 60,000 EUR |
| Security/audit effort | Moderate | High | Very high |
| Tenant onboarding cost | Near zero | Low | Provisioning to script |
| Cross-tenant leak risk | Must be scoped strictly | Low | Very low |
The 2026 lesson: a bad initial choice is paid in migration. Moving from database-per-tenant to shared (or vice versa) on a live product easily costs 25,000 to 50,000 EUR and several weeks of frozen roadmap.
Mini case study
Sofia, CTO of a SaaS scale-up in Berlin, runs 60 tenants. She starts on a shared database (run 420 EUR/month). A large banking account requires data isolation and European residency. Rather than move everything to database-per-tenant (projected run of 1,900 EUR/month for the whole base), she adopts the hybrid: the 59 clients stay pooled, the large account moves to a dedicated database. Monthly surcharge: +280 EUR instead of +1,480 EUR. She signs the contract at 4,200 EUR/month MRR while saving 14,400 EUR of run over the year versus blanket isolation.
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FAQ
Which model should I start with?
In 8 out of 10 cases, the shared database with logical partitioning (RLS): 200 to 600 EUR/month run, 6,000 to 12,000 EUR isolation dev. You keep the door open toward hybrid.
When should I move to per-tenant isolation?
As soon as a large account requires it contractually, or a regulation mandates data residency. The hybrid model avoids imposing that surcharge on all clients.
How much does an architecture migration cost afterward?
Between 25,000 and 50,000 EUR for a product in production, plus a frozen roadmap for several weeks. That is the argument for choosing well from the start.
Is strong isolation enough to be compliant?
No: it helps, but compliance also depends on encryption, logging and access policies. Architecture is a condition, not a guarantee.
Does multi-tenancy affect pricing?
Yes: an isolated tenant costs more to operate, which justifies an enterprise tier 3 to 5 times higher than the standard tier.
Let's scope your project. Share your target tenant count, your compliance requirements and your acceptable run budget, and we'll frame the architecture that protects your margin. 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.
