Published 2026-06-12 · reference prices, verify before budgeting
"Which AI API is cheapest?" has no answer until you fix a workload. So we did. Same job on every major model: 1,000,000 requests, each with 1,000 input tokens and 500 output tokens (a typical short chatbot or generation call). That's 1 billion input tokens and 500 million output tokens. Here's what each provider charges.
| Model | In $/1M | Out $/1M | Cost for 1M requests |
|---|---|---|---|
| Gemini 2.0 Flash cheapest | $0.10 | $0.40 | $300 |
| GPT-4o mini | $0.15 | $0.60 | $450 |
| DeepSeek-V3 | $0.27 | $1.10 | $820 |
| Gemini 2.5 Flash | $0.30 | $2.50 | $1,550 |
| Claude Haiku 3.5 | $0.80 | $4.00 | $2,800 |
| GPT-4o | $2.50 | $10.00 | $7,500 |
| Claude Sonnet 4 | $3.00 | $15.00 | $10,500 |
Same workload. $300 on Gemini 2.0 Flash, $10,500 on Claude Sonnet 4 — a 35× spread for the exact same number of requests. The model you pick is, by a wide margin, the biggest lever on your AI bill.
The catch every honest comparison has to add: a cheaper model that needs two tries, or writes longer answers, can cost more than a pricier one that nails it first time. Quality matters. The smart pattern most teams land on is tiering: a cheap model (Gemini Flash, GPT-4o mini, DeepSeek) for routine, high-volume calls, and a frontier model (GPT-4o, Claude Sonnet) only for the hard requests. Even sending 20% of traffic to a frontier model keeps you near the cheap end of this table.
After model choice, two things move the needle: output length (output is billed 4–5× input on every provider here — cap it) and prompt caching (repeated context billed at a steep discount on OpenAI, Anthropic and DeepSeek). Trim the system prompt, cap max_tokens, and cache what repeats.
Your tokens aren't ours. Plug your real input/output lengths and volume into the AI API cost calculator — it ranks every model for your numbers. Building something specific? Use the AI app cost estimator, the chatbot cost calculator or the RAG cost calculator. Per-model deep dives: GPT-4o, Claude, Gemini, DeepSeek.
Open the AI API Cost Calculator → · OpenAI vs Claude vs Gemini →
Reference prices (June 2026). Verify on each provider's pricing page before budgeting. Not affiliated with any provider.