PriceIndex

AI model capabilities

AI models that support function calling

Connect model responses to your application’s functions and external tools. Compare 285 supporting models by input price, output price, context window and published intelligence. Find the cheapest option for a reference text workload, then check the serving API before you build.

285 supporting models32 AI providersUSD · prices per 1M tokens

Lowest reference cost

Llama 3.1 8B Instruct

$0.03

1M input + 250K output tokens. Tool fees and discounts excluded.

Highest published intelligence

Claude Opus 5.5

57.6 AA Intelligence Index

Among supporting models with a published score; not a capability-specific benchmark.

Cheapest AI models with function calling

Ranked by the cost of 1 million input and 250,000 output tokens at standard rates. A different token mix can change the cheapest model. Support requires an explicitly listed catalog feature, not an inference from a model family.

GLM 5.3 FlashZ.ai
Input /1M
$0.03
Output /1M
$0.08
Reference cost
$0.05
Context
1M
AA Intelligence
41.8
gpt-oss-20bOpenAI
Input /1M
$0.03
Output /1M
$0.13
Reference cost
$0.06
Context
131K
AA Intelligence
9
Qwen3.7 FlashQwen
Input /1M
$0.03
Output /1M
$0.13
Reference cost
$0.06
Context
1M
AA Intelligence
—
Gemma 3 12BGoogle
Input /1M
$0.05
Output /1M
$0.15
Reference cost
$0.09
Context
131K
AA Intelligence
3.8

Showing 15 of 285

285 matching models · Missing intelligence scores are shown as —.

What is function calling?

Function calling lets a model request an operation using a named function and arguments. Your application decides whether to execute it and returns the result. It is useful for database lookups, workflow automation and assistants that act on business systems.

Before choosing a model

  • Validate arguments and permissions before executing a function.
  • Test tool selection and argument accuracy on your own tasks.
  • Account for the tokens used by function definitions and returned results.

Estimate your actual workload

Use your request volume and prompt and response sizes to compare monthly text-token costs. Add any search, external tool or provider-specific charges separately. Standard token prices do not assume cache hits or batch discounts.

LLM token cost calculator Pricing methodology

Function calling FAQs

285 active models with positive input and output prices currently list function calling in the PriceIndex catalog. The table lists every match. A model is included only when its tracked feature data explicitly lists this capability; missing data is not treated as support.

Llama 3.1 8B Instruct has the lowest estimated text-token cost in this list for 1 million input tokens and 250,000 output tokens: $0.0300. A different input/output mix can change the ranking. This excludes tool fees, caching, discounts and taxes.

No. Capability availability can differ between serving APIs and model versions. Follow a model’s API documentation link and verify the exact version, endpoint and settings before choosing it.

We use standard USD input and output token prices: input price × 1 million tokens plus output price × 250,000 tokens, divided by 1 million. The directory excludes retired models, missing prices and zero-priced entries. Published AA Intelligence Index scores are shown when available and never estimated.

Validate arguments and permissions before executing a function. Test tool selection and argument accuracy on your own tasks. Account for the tokens used by function definitions and returned results.

Explore more AI capabilities