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Best LLM for Function Calling

4 models ranked for function calling tasks. Sorted by benchmark quality score, with price as a secondary factor.

Best Quality
GPT-5.4
OpenAI
ELO 1420
Cheapest Option
Gemini 3 Flash
Google
$0.50/1M/1M input

All Models for Function Calling

#ModelProviderInput / 1MOutput / 1MELOFlags
🥇GPT-5.4OpenAI$2.50/1M$15.00/1M1420
🥈Claude Sonnet 4.6Anthropic$3.00/1M$15.00/1M1390
🥉Gemini 3 FlashGoogle$0.50/1M$3.00/1M1370
4GPT-5.4 miniOpenAI$0.75/1M$4.50/1M1360

Why We Picked These Models

GPT-5.4
$2.50/1M/1MELO 1420

GPT-5. OpenAI flagship — top-tier reasoning, coding, and multimodal.

Claude Sonnet 4.6
$3.00/1M/1MELO 1390

Claude Sonnet 4. Best combination of speed and intelligence in the Claude family.

Gemini 3 Flash
$0.50/1M/1MELO 1370

Gemini 3 Flash Preview brings Gemini 3-generation quality to the Flash tier, with stronger reasoning than 2. Gemini 3-generation quality at Flash pricing.

Compare Top Models

GPT-5.4 vs Claude Sonnet 4.6GPT-5.4 vs Gemini 3 FlashGPT-5.4 vs GPT-5.4 miniClaude Sonnet 4.6 vs Gemini 3 Flash

Frequently Asked Questions

What is the best LLM for function calling?

GPT-5.4 by OpenAI is rated as the best model for function calling with an ELO score of 1420. OpenAI flagship — top-tier reasoning, coding, and multimodal.

What is the cheapest LLM for function calling?

Gemini 3 Flash is the most affordable option for function calling at $0.50/1M per 1M input tokens.

Is there a free LLM for function calling?

No completely free models are listed for function calling, but Gemini 3 Flash start at very low prices.