Cheapest by the Numbers
If cost per token is the priority, a handful of models are dramatically cheaper than the flagships — often 20–100x on output, where most agent and codegen spend concentrates. Ranked by list price (per 1M tokens, input / output):
| Model | Input | Output | Note |
|---|---|---|---|
| DeepSeek V4 Flash | $0.14 | $0.28 | 98% cache discount, 1M context |
| Gemini 2.5 Flash-Lite | $0.10 | $0.40 | fast, high-volume |
| MiniMax M2.7 | $0.30 | $1.20 | agent-trained, open-weight |
| Gemini 2.5 Flash | $0.30 | $2.50 | balanced workhorse |
| DeepSeek V4 Pro | ~$0.44 | ~$0.87 | promo; reasoning-grade |
| Kimi K2.6 | $0.95 | $4.00 | cache-hit $0.16 |
| GLM-5.1 | ~$1.40 | ~$4.40 | 8-hr agentic |
Winner on raw price: DeepSeek V4 Flash. Gemini 2.5 Flash-Lite edges it on input but costs more on output; for output-heavy work, DeepSeek wins decisively.
Sticker Price Isn't the Whole Bill
The cheapest effective cost depends on your workload:
- Cache-heavy (agents, RAG, chatbots)? DeepSeek's automatic prefix caching cuts repeated input ~98% (to ~$0.0028/1M); Kimi's cache-hit is $0.16 vs $0.95. A model with great cache economics can beat a lower sticker price.
- Output-heavy (codegen, long answers)? Output rates dominate — DeepSeek V4 Flash's $0.28 output is the killer number.
- Reasoning "thinking" modes bill at the same rate but burn 3–5x more tokens. Keep them off by default.
The Two Tricks That Beat Any Sticker Price
- Route by difficulty. Send the bulk to a cheap model and escalate only hard tasks to a flagship — a 5–25x spread most teams never capture.
- Cache + batch. Prompt caching (up to ~90–98%) plus Batch API (50% off) can drop effective spend 95%+ on the right workload.
Full playbook in how to reduce AI API costs.
The Honest Caveats
The cheapest models are mostly open-weight Chinese labs (DeepSeek, MiniMax, GLM, Kimi). Two things to know: several store data in China on their official APIs (a GDPR/compliance consideration — self-hosting or a zero-retention gateway sidesteps it), and some carry Modified-MIT licenses that restrict commercial self-hosting. Using them through a gateway like LinkModel (zero data retention by default, up to 30% below official) handles both the data and billing side with one key.
Bottom Line
- Absolute cheapest, output-heavy → DeepSeek V4 Flash.
- Cheapest input for classification/routing → Gemini 2.5 Flash-Lite.
- Cheapest capable agent model → MiniMax M2.7.
- Then layer routing + caching + batch and the flagship-everything baseline disappears.
Compare against the premium tier in best LLM API and the full field in the AI API pricing comparison.
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