Cheapest AI model for hard reasoning
Top pick: Mistral Large 4 (Mistral) at about $27.70/mo for an example 10M input + 10M output tokens per month. Needs tier ≥3; 10 of 25 models qualify. Prices last checked 2026-10-13.
Cheapest qualifying models, ranked
| # | Model | Provider | Input $/M | Output $/M | Context | Tier | Example $/mo | vs top pick |
|---|---|---|---|---|---|---|---|---|
| 1 | Mistral Large 4 | Mistral | $0.68 | $2.09 | 1000000 | 3 | $27.70 | Top pick |
| 2 | DeepSeek V4 Pro | DeepSeek | $1.32 | $3.96 | 1000000 | 3 | $52.80 | +$25.10/mo |
| 3 | Grok 4.7 | xAI | $2.0 | $6.0 | 500000 | 3 | $80.00 | +$52.30/mo |
| 4 | GPT-6.1 Sol | OpenAI | $2.0 | $10.0 | — | 3 | $120.00 | +$92.30/mo |
| 5 | Claude Sonnet 5.5 | Anthropic | $2.0 | $10.0 | — | 3 | $120.00 | +$92.30/mo |
Caveat: Reasoning models spend extra 'thinking' tokens billed as output, so real cost can be several times this estimate.
How the example bill is computed
We assume 10M input and 10M output tokens per month and multiply by each model's standard per-1M-token price. For the top pick, Mistral Large 4 (Mistral): (10M × $0.68) + (10M × $2.09) = $27.70 per month (prices checked 2026-10-13).
Tiers 1–4 are our own rough capability judgment (1 = light, 4 = frontier), not a benchmark. This job needs tier ≥3, so only those models are ranked (10 of 25 qualify). Standard pay-as-you-go text prices only: no batch or cached-input discounts. Cost only, not quality; different tokenizers count the same text differently.
Related head-to-head comparisons
- Claude Sonnet 5.5 vs GPT-6.1 Sol
- Grok 4.7 vs GPT-6.1 Sol
- Gemini 3.1 Pro Preview vs Claude Sonnet 5.5
- DeepSeek V4 Pro vs GPT-6.1 Sol
- Mistral Large 4 vs DeepSeek V4 Pro
Other jobs: Simple Q&A / chat · Coding · Long documents. See every model on the full price table or estimate your own bill with the savings calculator.