Head-to-head · frontier vs frontier

Claude Sonnet 4.5 Max vs GPT-5.2: which model should you choose?

We compared Claude Sonnet 4.5 Max and GPT-5.2 on price, context window and 12 benchmarks. GPT-5.2 has the stronger average benchmark score; GPT-5.2 is cheaper on a blended 3:1 basis.

Anthropic

Claude Sonnet 4.5 Max

Claude Sonnet 4.5 Max is a frontier model from Anthropic. It offers a 1,000,000-token context window, costs $19.90 per million input tokens and $95.47 per million output tokens, and averages 87.2 across the index's benchmark suite.

Input: $19.90 / 1M
Output: $95.47 / 1M
Context: 1,000,000
Avg score: 87.2
Open weights: No

Full Claude Sonnet 4.5 Max page

OpenAI

GPT-5.2

GPT-5.2 is a frontier model from OpenAI. It offers a 2,000,000-token context window, costs $19.71 per million input tokens and $85.71 per million output tokens, and averages 88.0 across the index's benchmark suite.

Input: $19.71 / 1M
Output: $85.71 / 1M
Context: 2,000,000
Avg score: 88.0
Open weights: No

Full GPT-5.2 page

Specification comparison

Spec	Claude Sonnet 4.5 Max	GPT-5.2	Edge
Input price / 1M	$19.90	$19.71	B
Output price / 1M	$95.47	$85.71	B
Context window	1,000,000	2,000,000	B
Max output	65,536	16,384	A
Average score	87.2	88.0	B
Arena Elo	1474.9	1478.0	B
Open weights	No	No	Tie

Benchmark comparison

Claude Sonnet 4.5 Max wins 4, GPT-5.2 wins 7, and 1 benchmarks are tied. The table shows the modelled score for each model and the gap.

Benchmark	Claude Sonnet 4.5 Max	GPT-5.2	Gap	Winner
MMLU-Pro	86.1	89.9	3.8	GPT-5.2
GPQA Diamond	84.4	84.9	0.5	GPT-5.2
SWE-bench Verified	80.2	80.2	0.0	Tie
HumanEval	92.4	91.0	1.4	Claude Sonnet 4.5 Max
MATH-500	92.8	90.6	2.2	Claude Sonnet 4.5 Max
AIME 2025	85.4	90.6	5.2	GPT-5.2
LiveCodeBench	82.8	79.7	3.1	Claude Sonnet 4.5 Max
IFEval	92.9	93.6	0.7	GPT-5.2
TruthfulQA	87.3	89.7	2.4	GPT-5.2
HellaSwag	93.1	92.6	0.5	Claude Sonnet 4.5 Max
MMMU	82.0	85.3	3.3	GPT-5.2
Arena Elo	1474.9	1478.0	3.1	GPT-5.2

Price analysis

On a blended 3:1 input-to-output basis, Claude Sonnet 4.5 Max costs about $38.79 per million tokens and GPT-5.2 costs about $36.21. GPT-5.2 is roughly 7% cheaper than Claude Sonnet 4.5 Max. At high volume, that gap compounds quickly, so price should carry real weight unless the quality difference is decisive.

GPT-5.2 has the larger context window at 2,000,000 tokens, compared with 1,000,000 for Claude Sonnet 4.5 Max. That matters for long documents, large codebases and multi-step agent traces.

Verdict

Across 12 shared benchmarks, Claude Sonnet 4.5 Max wins 4, GPT-5.2 wins 7, and 1 are tied. On the index average, GPT-5.2 leads Claude Sonnet 4.5 Max by 0.8 points (88.0 versus 87.2).

The price picture favours GPT-5.2. The context picture favours GPT-5.2. Those two dimensions often matter more than a few benchmark points once a model is good enough for the task.

If you need a single default, start with GPT-5.2 for quality-sensitive work, and check whether its price holds at your expected volume before committing.

Choose Claude Sonnet 4.5 Max if

You need the larger 65,536-token output limit.

Choose GPT-5.2 if

You want the higher average benchmark score in this index.
Unit cost matters and you want the cheaper blended price.
You need the larger 2,000,000-token context window.

FAQ

Is Claude Sonnet 4.5 Max better than GPT-5.2?

On the index average, GPT-5.2 leads Claude Sonnet 4.5 Max by 0.8 points (88.0 versus 87.2). The better choice depends on price, context and your task. Claude Sonnet 4.5 Max wins 4 benchmarks, GPT-5.2 wins 7.

Which is cheaper, Claude Sonnet 4.5 Max or GPT-5.2?

GPT-5.2 is cheaper on a blended 3:1 basis at about $36.21 per million tokens, versus $38.79 for Claude Sonnet 4.5 Max.

Which has the larger context window?

GPT-5.2 has the larger context window at 2,000,000 tokens. Claude Sonnet 4.5 Max has 1,000,000 tokens.

Are these models open weights?

Claude Sonnet 4.5 Max is proprietary; GPT-5.2 is proprietary.

Which should I choose for production?