Quick Answer
Best Cheap AI API 2026: Price Per Task Ranked
The Short Answer
The cheapest usable AI API in 2026 is DeepSeek V4 Flash 0731 (~$0.0056/task off-peak), and it’s genuinely good at coding. For general work, Gemini 3.5 Flash-Lite and GPT-5.6 Luna follow. Always compare cost per task, not sticker per-token rates.
Ranked by Cost Per Task (30K in / 5K out)
| Rank | Model | Price (per MTok) | Cost / task | Best for |
|---|---|---|---|---|
| 1 | DeepSeek V4 Flash 0731 | $0.14 / $0.28* | ~$0.0056 | Cheap coding agents |
| 2 | Gemini 3.5 Flash-Lite | $0.30 / $2.50 | ~$0.022 | Cheap general/multimodal |
| 3 | DeepSeek V4 Pro | $0.435 / $0.87* | ~$0.017 | Cheap deep reasoning |
| 4 | GPT-5.6 Luna | $1 / $6 | ~$0.06 | Cheap OpenAI-stack |
| 5 | Gemini 3.6 Flash | $1.50 / $7.50 | ~$0.0825 | Efficient multimodal default |
| 6 | Grok 4.5 | $2 / $6 | ~$0.09** | Value agentic coding |
*DeepSeek doubles during peak hours (~1–4 & 6–10 UTC). **Grok’s ~2× step efficiency lowers real-task cost.
How to Read This
- Per-token ≠ per-task. Output rates dominate most tasks; a low input rate with a high output rate (like Flash-Lite’s $2.50 out) costs more than it looks.
- Cache hits change everything. DeepSeek V4 Flash cache-hit input is $0.0028/MTok — near-free for repeated context.
- Efficiency is a hidden discount. Grok 4.5 solves tasks in under half the steps; Gemini 3.6 Flash uses ~65% fewer output tokens than 3.5 Flash.
Match the Model to the Job
- High-volume coding → DeepSeek V4 Flash 0731
- Cheapest general chat → Gemini 3.5 Flash-Lite
- Cheap OpenAI ecosystem → GPT-5.6 Luna
- Value agentic coding → Grok 4.5
- Hardest refactors (worth paying up) → Claude Opus 5 ($5/$25)
Sources
- DeepSeek API pricing: api-docs.deepseek.com/quick_start/pricing
- OpenRouter model pricing: openrouter.ai/models