Use case ยท checked October 12, 2026
Cheapest LLM API for support chatbot
Claude Haiku 5.5 and GPT-6 Luna tie as the cheapest at $18.00 a month. Our assumption: 60,000 conversations a month, each turn sending about 1,500 tokens (system prompt, history and the user's question) and getting a 300-token answer back.
| # | Model | Per month | Per request |
|---|---|---|---|
| 1 | Claude Haiku 5.5 | $18.00 | $0.00030 |
| 2 | GPT-6 Luna | $18.00 | $0.00030 |
| 3 | DeepSeek V4.1 Flash | $24.30 | $0.00041 |
| 4 | Gemini 3.1 Flash-Lite | $49.50 | $0.00082 |
| 5 | Gemini 3.5 Flash-Lite | $72.00 | $0.00120 |
| 6 | Mistral Large | $72.00 | $0.00120 |
| 7 | DeepSeek V4 Pro | $95.04 | $0.00158 |
| 8 | Grok Build 0.1 | $126 | $0.00210 |
| 9 | Gemini 3.8 Flash | $135 | $0.00225 |
| 10 | Gemini 3.6 Flash | $135 | $0.00225 |
| 11 | Grok 4.3 | $158 | $0.00263 |
| 12 | Claude Haiku 4.5 | $180 | $0.00300 |
| 13 | Grok 4.7 | $288 | $0.00480 |
| 14 | Claude Sonnet 5.5 | $360 | $0.00600 |
| 15 | GPT-6.1 Sol | $360 | $0.00600 |
| 16 | Gemini 3.1 Pro | $396 | $0.00660 |
| 17 | GPT-5.3 Codex | $410 | $0.00683 |
| 18 | Claude Opus 5.5 | $720 | $0.01200 |
| 19 | Claude Fable 5.1 | $1,800 | $0.03000 |
| 20 | GPT-6 Astra | $1,800 | $0.03000 |
Change the assumptions
Start from a use case
1,000 tokens is about 750 English words. Input includes your system prompt, chat history and any retrieved documents.
Claude Haiku 5.5
AnthropicCheapest
$18.00 /mo
GPT-6 Luna
OpenAICheapest
$18.00 /mo
DeepSeek V4.1 Flash
DeepSeek
$24.30 /mo
Gemini 3.1 Flash-Lite
Google
$49.50 /mo
Gemini 3.5 Flash-Lite
Google
$72.00 /mo
Mistral Large
Mistral
$72.00 /mo
DeepSeek V4 Pro
DeepSeek
$95.04 /mo
$126 /mo
Gemini 3.8 Flash
Google
$135 /mo
Gemini 3.6 Flash
Google
$135 /mo
Grok 4.3
xAI
$158 /mo
Claude Haiku 4.5
Anthropic
$180 /mo
Grok 4.7
xAI
$288 /mo
Claude Sonnet 5.5
Anthropic
$360 /mo
GPT-6.1 Sol
OpenAI
$360 /mo
Gemini 3.1 Pro
Google
$396 /mo
GPT-5.3 Codex
OpenAI
$410 /mo
Claude Opus 5.5
Anthropic
$720 /mo
Claude Fable 5.1
Anthropic
$1,800 /mo
GPT-6 Astra
OpenAI
$1,800 /mo