AI cost calculator per LLM model
Compare what AI will cost your team per month — across OpenAI, Anthropic, Google and Mistral. Built for European SMEs that need GDPR-proof AI without surprise invoices. No tokens to count, no signup, no credit card.
Cost per provider — cheap vs flagship model
| Provider | Cheap model | Flagship model |
|---|---|---|
| OpenAI | GPT-5.4 Mini €3/month · €31/year | GPT-5.5 €17/month · €208/year |
| Anthropic | Claude Haiku 4.5 €3/month · €37/year | Claude Opus 4.7 €16/month · €187/year |
Gemini 2.5 Flash €1/month · €15/year | Gemini 3.1 Pro €7/month · €83/year | |
| Mistral | Mistral Small 3 €0/month · €3/year | Mistral Large 2 €5/month · €59/year |
Most AI tools send every task to one model. With Custos multi-LLM, you pick the right model per workflow — and that choice is what compounds into the savings below.
€9.60/user/mo · €115/user/year
Estimates based on typical SME usage patterns. Actual costs vary with prompt length, output length and caching. Provider prices in USD, converted to EUR at a fixed rate of 0.92. Sources: openai.com/api/pricing, anthropic.com/pricing, ai.google.dev/gemini-api/docs/pricing, mistral.ai/pricing. Last verified: 8 May 2026. Custos platform: €12/user/month, or €9.60/user/month with annual billing (-20%). All prices excl. VAT.
How Custos prevents bill shock
Custos blocks the API call before it costs you money. Set a monthly ceiling per user or team. The cap holds — no retroactive surprise.
What you'll see
Provider comparison
Side-by-side monthly cost across the four providers Custos supports. No vendor bias — Custos charges no markup on AI usage. You pay the provider directly through your own keys.
Multi-LLM in one workspace
Most AI tools lock you into one model. Custos gives you all four providers — OpenAI, Anthropic, Google, Mistral — in one workspace. You pick the right model per workflow: light tasks on cheap models, complex jobs on premium models. Typical saving when used well: 60-80% versus running everything on a flagship.
Hard budget caps
Custos blocks the API call before it costs you money. Set a monthly ceiling per user or per team. No more watching a runaway prompt drain your budget overnight.
GDPR-proof by default
Custos is hosted in Frankfurt and Amsterdam. Data stays in the EU. Zero data retention with all four providers. Compliant with GDPR, AVG, DSGVO and RGPD out of the box.
How to choose the right model in Custos
For light, high-volume work
customer emails, short translations, product descriptions, classifications
→ Mistral Small 3 or Gemini 2.5 Flash
Fast, cheap, quality is fine for this work.
€0.001 — €0.003 per call
For mid-weight work
summaries, business writing, email templates, simple code
→ GPT-5.4 Mini or Claude Haiku 4.5
Good balance between price and quality.
€0.01 — €0.05 per call
For heavy thinking
contract analysis, long files, complex code review, legal reasoning
→ Claude Opus 4.7, GPT-5.5, or Mistral Large 2
Premium price, premium result.
€0.15 — €0.40 per call
For long context
200K+ tokens, full case files, codebases
→ GPT-5.5 (1M token context) or Claude Opus 4.7 (200K)
Nothing else holds coherence end-to-end.
from €0.50 per call
In Custos you see these options with price comparison side by side, before you start the chat. Switch a lot? Set your preference per project — Custos remembers it. Choose once, automatically the right model for you and your team going forward.
Frequently asked questions
How much does AI cost per employee per month?
For typical SME use — drafting emails, summarising meetings, translating documents — most teams spend €5 to €25 per user per month on AI provider fees, plus €12-€15 for the Custos workspace. Heavy users (legal, technical writing, code review) can reach €40-€80. Choosing the right model per workflow typically reduces this by 60-80%.
What's the difference between BYOK and a managed AI subscription?
BYOK (Bring Your Own Key) means you pay the AI provider — OpenAI, Anthropic, Google, Mistral — directly. Custos adds zero markup on usage. A managed subscription bundles AI and platform into one bill, usually with a 2x-3x markup. BYOK is cheaper and more transparent for businesses with predictable usage.
Which AI model is cheapest for European SMEs?
For high-volume routine tasks (translations, classifications, short emails), Mistral Small 3 and Gemini 2.5 Flash are the most cost-effective. For complex reasoning (contract review, long analysis), Mistral Large 2 offers the best price-to-quality ratio. Custos surfaces the cost per model so you pick the right one per task.
Are these prices in euros or dollars?
Provider list prices are published in USD. We convert to EUR at a fixed rate displayed on the page. Custos's own platform fees are billed in EUR (excl. VAT). NL customers add 21% VAT; EU B2B with a valid VAT number is 0% (reverse charge).
Does Custos charge a markup on AI usage?
No. Custos uses the BYOK model — you connect your own API keys and pay the provider directly. We charge a flat platform fee per user per month and never take a percentage of your AI spend. Your AI invoice goes to OpenAI, Anthropic, Google or Mistral, not to us.
How does Custos prevent AI bill shock?
Hard budget caps enforced at the proxy layer. You set a monthly ceiling per user, team, or workspace. Custos checks the cap before every API call and blocks requests once you hit the limit. No retroactive surprise — the cap holds.