Cheapest AI model for a chatbot
Chatbot turns are short on both ends — usually 100-300 input tokens and 50-150 output tokens. At this shape, input pricing dominates the bill. We ranked every non-deprecated model on that exact workload.
Ranked cheapest first
| # | Model | Input $/M | Output $/M | Per 1M calls |
|---|---|---|---|---|
| #1 | GPT-5 Nano OpenAI |
$0.05 | $0.40 | $50 |
| #2 | Llama 3.1 8B Meta |
$0.18 | $0.18 | $54 |
| #3 | GPT-4.1 Nano OpenAI |
$0.10 | $0.40 | $60 |
| #4 | Gemini 2.5 Flash-Lite |
$0.10 | $0.40 | $60 |
| #5 | GPT-4o mini OpenAI |
$0.15 | $0.60 | $90 |
| #6 | DeepSeek V3 DeepSeek |
$0.27 | $1.10 | $164 |
| #7 | GPT-5.4 Nano OpenAI |
$0.20 | $1.25 | $165 |
| #8 | Llama 3.1 70B Meta |
$0.59 | $0.79 | $197 |
| #9 | Gemini 3.1 Flash-Lite |
$0.25 | $1.50 | $200 |
| #10 | GPT-4.1 Mini OpenAI |
$0.40 | $1.60 | $240 |
| #11 | Qwen 2.5 Coder 32B Alibaba |
$0.80 | $0.80 | $240 |
| #12 | GPT-5 Mini OpenAI |
$0.25 | $2.00 | $250 |
| #13 | Llama 3.3 70B Meta |
$0.88 | $0.88 | $264 |
| #14 | Qwen 2.5 72B Alibaba |
$0.90 | $0.90 | $270 |
| #15 | DeepSeek V3.1 DeepSeek |
$0.60 | $1.70 | $290 |
| #16 | Gemini 2.5 Flash |
$0.30 | $2.50 | $310 |
| #17 | Gemini 3 Flash |
$0.50 | $3.00 | $400 |
| #18 | GPT-5.4 Mini OpenAI |
$0.75 | $4.50 | $600 |
| #19 | Qwen3 Coder 480B Alibaba |
$2.00 | $2.00 | $600 |
| #20 | o3-mini OpenAI |
$1.10 | $4.40 | $660 |
| #21 | o4-mini OpenAI |
$1.10 | $4.40 | $660 |
| #22 | Claude Haiku 4.5 Anthropic |
$1.00 | $5.00 | $700 |
| #23 | GLM-5.1 zhipu |
$1.40 | $4.40 | $720 |
| #24 | Mistral Large Mistral |
$2.00 | $6.00 | $1,000 |
| #25 | Llama 3.1 405B Meta |
$3.50 | $3.50 | $1,050 |
| #26 | GPT-4.1 OpenAI |
$2.00 | $8.00 | $1,200 |
| #27 | o3 OpenAI |
$2.00 | $8.00 | $1,200 |
| #28 | GPT-5.1 OpenAI |
$1.25 | $10.00 | $1,250 |
| #29 | GPT-5 OpenAI |
$1.25 | $10.00 | $1,250 |
| #30 | Gemini 2.5 Pro |
$1.25 | $10.00 | $1,250 |
| #31 | DeepSeek R1 DeepSeek |
$3.00 | $7.00 | $1,300 |
| #32 | GPT-4o OpenAI |
$2.50 | $10.00 | $1,500 |
| #33 | Gemini 3.1 Pro |
$2.00 | $12.00 | $1,600 |
| #34 | GPT-5.3 OpenAI |
$1.75 | $14.00 | $1,750 |
| #35 | GPT-5.2 OpenAI |
$1.75 | $14.00 | $1,750 |
| #36 | GPT-5.4 OpenAI |
$2.50 | $15.00 | $2,000 |
| #37 | Claude Sonnet 4.6 Anthropic |
$3.00 | $15.00 | $2,100 |
| #38 | Claude Opus 4.8 Anthropic |
$5.00 | $25.00 | $3,500 |
| #39 | GPT-5.5 OpenAI |
$5.00 | $30.00 | $4,000 |
| #40 | GPT-4 Turbo OpenAI |
$10.00 | $30.00 | $5,000 |
| #41 | Claude Opus 4.8 (Fast Mode) Anthropic |
$10.00 | $50.00 | $7,000 |
| #42 | o3-pro OpenAI |
$20.00 | $80.00 | $12,000 |
| #43 | GPT-5 Pro OpenAI |
$15.00 | $120.00 | $15,000 |
| #44 | GPT-5.2 Pro OpenAI |
$21.00 | $168.00 | $21,000 |
| #45 | GPT-5.5 Pro OpenAI |
$30.00 | $180.00 | $24,000 |
| #46 | GPT-5.4 Pro OpenAI |
$30.00 | $180.00 | $24,000 |
Workload assumption: 200 input tokens + 100 output tokens per call, scaled to 1M calls. Pricing as of 2026-05-31.
How to use this ranking
The winner is mathematically cheapest at the listed workload shape — that's not the same as "best for the use case." Cheaper models often have lower reasoning depth, smaller context windows, or worse instruction-following. Use this as the cost baseline, then test the top 2-3 candidates on your real prompts via the live counter.
Pricing snapshots come from each provider's published rate cards and are tracked in the full pricing changelog. Tokenizer accuracy per model is documented in the methodology.