GPT-4o vs Claude 3.5 Sonnet: Which AI Is Actually Better in 2025?

GPT-4o and Claude 3.5 Sonnet are the two most widely used AI models in 2025. After testing both across eight task categories with identical prompts, the verdict is clear: neither model dominates across the board, and the right choice depends entirely on your use case.

The Eight-Category Test

We ran 40 standardized prompts across GPT-4o (OpenAI's flagship multimodal model) and Claude 3.5 Sonnet (Anthropic's mid-tier workhorse) and scored outputs on accuracy, coherence, and usefulness. Here's what we found.

Coding: Claude Takes the Lead

Claude 3.5 Sonnet outperforms GPT-4o on coding tasks, particularly for larger codebases and architectural problems. Claude produces cleaner, more idiomatic code with better adherence to specified patterns.

On HumanEval, Claude 3.5 Sonnet scores 93.7% versus GPT-4o's 90.2%. The difference is most visible on tasks requiring multi-file awareness and refactoring. GPT-4o tends toward verbose implementations; Claude writes tighter, more maintainable code.

Where GPT-4o wins: rapid one-off scripts and tasks that benefit from its multimodal capability (reading screenshots of error messages, for example).

Writing: Claude Is the Better Writer

Claude 3.5 Sonnet produces noticeably better long-form writing. Its outputs have more varied sentence structure, stronger narrative flow, and fewer of the telltale AI patterns (excessive use of "furthermore," "in conclusion," transition phrases).

For email drafts, marketing copy, and short-form content, GPT-4o is competitive and often faster. But for blog posts, essays, documentation, and anything where voice and tone matter, Claude is the stronger choice.

Math and Reasoning: GPT-4o's Edge

GPT-4o scores higher on structured mathematical reasoning, particularly multi-step problems. On MATH benchmark tasks, GPT-4o achieves 76.6% versus Claude's 73.4%. For symbolic reasoning, logical puzzles, and problems requiring precise step-by-step calculation, GPT-4o is more reliable.

Both models make arithmetic errors on complex calculations — neither should be trusted for high-stakes math without verification. For reasoning-heavy tasks, OpenAI's o3 model (a dedicated reasoning model) outperforms both.

Instruction Following: Claude's Strongest Advantage

Claude 3.5 Sonnet is dramatically better at following precise, multi-part instructions. When given a prompt with five specific requirements, Claude consistently honors all five. GPT-4o frequently drops requirements or partially fulfills them.

This matters for workflows where you're using AI to generate structured outputs: formatted reports, content with specific constraints, code matching a particular style guide. Claude's precision here makes it significantly more useful for professional and production contexts.

Speed and Cost

Both models are similar in response speed for typical queries. GPT-4o runs at approximately 100–120 tokens per second; Claude 3.5 Sonnet at 90–110 tokens per second. The difference is imperceptible in interactive use.

Pricing via API: GPT-4o costs $2.50/M input tokens and $10/M output tokens. Claude 3.5 Sonnet costs $3.00/M input and $15/M output. For most use cases the difference is negligible; at scale, GPT-4o is modestly cheaper.

Multimodal Capabilities

GPT-4o has a significant advantage in image understanding. It processes images more accurately, handles OCR better, and integrates visual context more naturally into responses. If your workflow involves analyzing images, charts, or screenshots, GPT-4o is the better choice.

Claude 3.5 Sonnet also supports vision inputs but is less reliable on complex visual tasks. For pure text workflows, this distinction doesn't matter.

Use Case Recommendation Matrix

The Case for Using Both

The most powerful approach isn't choosing between GPT-4o and Claude — it's using both simultaneously. Running the same prompt through both models takes seconds and gives you two independent perspectives. For important decisions, creative work, or research, the combined output consistently outperforms either model alone.

When both models agree, you have high confidence in the answer. When they disagree, that divergence reveals complexity worth investigating further.

Frequently Asked Questions

Is Claude 3.5 Sonnet better than GPT-4o overall?

Claude 3.5 Sonnet wins on writing, coding, and instruction following. GPT-4o wins on math and image understanding. For most text-heavy professional tasks, Claude is the better default. For multimodal and mathematical tasks, GPT-4o has the edge.

Which model is cheaper?

GPT-4o costs $2.50/M input tokens and $10/M output tokens. Claude 3.5 Sonnet costs $3.00/M input and $15/M output. GPT-4o is modestly cheaper at scale, though for interactive use the cost difference is minimal.

Can I use both models without separate subscriptions?

Yes. Deepest gives you access to both GPT-4o and Claude 3.5 Sonnet through a single subscription, along with 300+ other models. You can run prompts through both simultaneously and compare responses directly.

Which model is faster?

Both are comparable for interactive use. GPT-4o runs slightly faster at approximately 100–120 tokens per second versus Claude's 90–110. For latency-sensitive production applications, consider their respective mini/haiku variants which are significantly faster.