- Claude 3.5 Sonnet scores 92.0% on HumanEval versus GPT-4o's 90.2%, with Claude preferred for complex coding tasks.
- Claude is widely regarded as the better writer with more natural prose, while GPT-4o excels at structured and multilingual writing.
- Claude 3.5 Sonnet outperforms GPT-4o on MMLU (89.0% vs 87.2%) and GPQA (59.4% vs 53.6%) with more methodical reasoning.
- GPT-4o costs $2.50/$10 per million tokens while Claude 3.5 Sonnet costs $3/$15, making Claude slightly more expensive.
- GPT-4o processes text, images, and audio natively as OpenAI's multimodal flagship, while Claude focuses on text.
- Choose Claude for writing and reasoning tasks, GPT-4o for multimodal applications and OpenAI ecosystem integrations.
Two Titans, One Question
GPTGPTGenerative Pre-trained Transformer — the model architecture and family name behind OpenAI's most famous models, from GPT-2 to GPT-5.Learn more →-4o and Claude 3.5 Sonnet are the two most widely deployed frontier models for everyday tasks. Both offer excellent instruction-following, strong coding ability, and long contextLong ContextThe ability of AI models to process extremely large inputs spanning tens of thousands to millions of tokens, enabling comprehensive analysis of entire documents, codebases, or datasets in a single context.Learn more → windows. But they have meaningfully different strengths that make one a better fit than the other depending on your use case.
GPT-4o is OpenAI's multimodalMultimodalCapable of processing and generating multiple types of data — such as text, images, audio, and video — within a single model.Learn more → flagship, processing text, images, and audio natively. Claude 3.5 Sonnet is Anthropic's mid-tier workhorse. It is faster and cheaper than Opus while approaching its quality on most tasks. Both began as Foundation Models and are deployed as Instruct Models aligned to follow user instructions.
Coding Performance
On HumanEvalHumanEvalA benchmark dataset of 164 Python programming problems used to evaluate code generation capabilities of language models through unit test pass rates.Learn more →, GPT-4o scores 90.2% and Claude 3.5 Sonnet scores 92.0%. In practice, both models excel at generating boilerplate, debugging, and code review. Claude has a slight edge for longer, more complex coding tasks where context management and file consistency matter.
For agentic codingAgentic CodingAI-assisted software development where the AI operates autonomously across multiple steps — reading files, executing code, observing results, and iterating — with minimal human intervention per action.Learn more →, both perform well. Claude's instruction-following precision gives it an advantage in structured coding workflows. If you are building a coding assistant or IDE integration, Claude 3.5 Sonnet is often the preferred choice among developers.
Writing and Creative Tasks
Claude is widely regarded as the better writer. Its prose is more naturally varied, its tone more calibrated, and it tends to avoid the slightly corporate cadence that GPT-4o can sometimes produce. For long-form content, marketing copy, and creative writing, Claude's outputs typically require less editing.
GPT-4o holds its own on structured writing tasks. Business emails, technical documentation, and report generation benefit from its more formal style. It is also notably stronger for multilingual writing, with better coverage of non-English languages due to OpenAI's training data breadth.
Reasoning and Analysis
On MMLUMMLUA comprehensive benchmark evaluating language models across 57 academic subjects from elementary to professional level using multiple-choice questions.Learn more → (broad knowledge) and GPQAGPQAA graduate-level, 'Google-proof' multiple-choice benchmark of hard science questions designed to resist easy lookup and test deep reasoning.Learn more → (graduate-level reasoning), GPT-4o scores 87.2% and 53.6% respectively. Claude 3.5 Sonnet scores 89.0% and 59.4%. For hard multi-step reasoning, Claude has a consistent edge. Its Chain of ThoughtChain of ThoughtA prompting technique that encourages an LLM to reason step by step before giving a final answer, dramatically improving performance on complex tasks.Learn more → reasoning is more methodical, and it shows lower hallucinationHallucinationWhen an AI model generates text that is factually incorrect, fabricated, or unsupported by its context, stated with confident fluency as if it were true.Learn more → rates on knowledge-intensive tasks.
If reasoning is your primary use case, consider upgrading to Claude 3.7 Sonnet with extended thinking enabled, or OpenAI's o4-mini. Both are purpose-built for deep reasoning and vastly outperform general-purpose models on hard problems.
Cost and Speed
GPT-4o charges $2.50/M input tokens and $10/M output tokens. Claude 3.5 Sonnet charges $3/M input and $15/M output. It is slightly more expensive but often worth it for quality-sensitive applications. Both stream responses quickly, though GPT-4o tends to have lower median latencyLatencyThe delay between sending a request to an LLM and receiving the first token of the response, often measured as Time to First Token (TTFT).Learn more →.
For high-volume applications where cost is paramount, consider Claude 3.5 Haiku ($0.80/$4.00) or GPT-4o Mini ($0.15/$0.60). Both offer strong value at drastically lower prices.
The Verdict
Choose Claude 3.5 Sonnet for long-form writing, nuanced reasoning, complex coding tasks, and applications where instruction-following precision matters. Choose GPT-4o for multimodal use cases involving image and text, multilingual applications, tight latency requirements, and OpenAI ecosystem integrations.
The good news: both models are exceptional. The difference in most everyday tasks is marginal. The best choice is often determined by ecosystem fit rather than raw capability. Try both on your specific tasks using Keimodel and let your actual use case decide.