LLM ComparisonGPT-5.1GPT-4o

GPT-5.1 vs GPT-4o

Compare GPT-5.1 and GPT-4o. Build AI products powered by either model on Appaca.

Model Comparison

FeatureGPT-5.1GPT-4o
ProviderOpenAIOpenAI
Model Typetexttext
Context Window400,000 tokens128,000 tokens
Input Cost
$1.25/ 1M tokens
$2.50/ 1M tokens
Output Cost
$10.00/ 1M tokens
$10.00/ 1M tokens

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Strengths & Best Use Cases

GPT-5.1

OpenAI

1. Configurable Reasoning for Agentic Tasks

  • Built to excel in autonomous or semi-autonomous coding workflows, with adjustable reasoning effort for planning, refactoring and debugging.

2. Fast Multi-Modal Input with Large Output

  • Accepts both text and image inputs while producing text outputs.
  • Offers up to 128 k output tokens, allowing long responses and code generation across multiple files.

3. Large Context & Knowledge Cut-Off

  • 400 k token context window supports processing large codebases or documents.
  • Knowledge cut-off of Sep 30 2024 ensures familiarity with recent tools and frameworks.

4. Reasoning Token Support

  • Provides explicit support for reasoning tokens, enabling developers to fine-tune the balance between reasoning depth and speed.

GPT-4o

OpenAI

1. High-intelligence, general-purpose model

  • Strong reasoning, creativity, summarization, and problem-solving.
  • Great balance of speed, accuracy, and cost.

2. Multimodal input support

  • Accepts text + image inputs for visual reasoning, extraction, or description.
  • Output is text only, making it predictable for production.

3. Excellent for structured and unstructured tasks

  • Performs well on Q&A, writing, analysis, classification, chat, and planning.
  • Supports Structured Outputs, making it suitable for deterministic workflows.

4. Strong tool-use capabilities

  • Supports function calling, API orchestration, and tool-augmented workflows.
  • Integrates well with assistants, batch operations, and automation pipelines.

5. Large context for complex tasks

  • 128K context allows multi-document reasoning, multi-step conversations, and large input payloads.

6. Production-ready reliability

  • Stable outputs, predictable behaviors, and broad modality coverage.
  • Supported across all major API endpoints.

7. Lower latency than o-series reasoning models

  • Faster responses due to no dedicated reasoning step.
  • Ideal for interactive or near-real-time applications.

8. Fine-tuning and distillation supported

  • Enables specialization for domain-specific tasks.
  • Distillation helps create smaller, efficient custom models.

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