Claude Opus 4.6 vs GPT-5.2 Pro
Claude Opus 4.6 (Anthropic, released Feb 2026) and GPT-5.2 Pro (OpenAI, released Dec 2025) are both flagship reasoning models aimed at agentic coding and long-running tasks. They land two months apart but land very differently on price and context: Opus 4.6 costs a fraction of GPT-5.2 Pro per token and handles 2.5x more context. Both are available on OpenKey with one API key and a flat 3% fee over provider list price.
Spec vs spec
| Spec | Claude Opus 4.6 | GPT-5.2 Pro |
|---|---|---|
| Context window | 1M | 400K |
| Max output | 128K | 128K |
| Input modalities | text, image, file | image, text, file |
| Output modalities | text | text |
| Released | Feb 4, 2026 | Dec 10, 2025 |
| Reasoning | optional | always on |
Pricing
Per 1M tokens. Provider price plus the flat 3% fee — the sum is what you pay.
anthropic/claude-opus-4.6
Input · 1M tokens
$5.00 + 3%$5.15
Output · 1M tokens
$25.00 + 3%$25.75
Cache read · 1M tokens
$0.500 + 3%$0.515
Cache write · 1M tokens
$6.25 + 3%$6.44
FEE — FLAT, EVERY MODEL3%
openai/gpt-5.2-pro
Input · 1M tokens
$21.00 + 3%$21.63
Output · 1M tokens
$168.00 + 3%$173.04
FEE — FLAT, EVERY MODEL3%
One workload, priced on both
10M input + 2M output tokens at each model's price, flat 3% fee included.
anthropic/claude-opus-4.6Cheaper
$103.00
$100.00 provider + 3%
openai/gpt-5.2-pro
$562.38
$546.00 provider + 3%
Pricing math on a real workload
Provider list price: Opus 4.6 runs $5/M input, $25/M output. GPT-5.2 Pro runs $21/M input, $168/M output — 4.2x the input cost and 6.7x the output cost. On OpenKey, add the flat 3% fee: Opus 4.6 becomes $5.15/M input and $25.75/M output; GPT-5.2 Pro becomes $21.63/M input and $173.04/M output.
Run the numbers on a concrete job — 10M input tokens plus 2M output tokens, a decent chunk of agentic work or a big codebase review. Opus 4.6 costs $100.00 for that job. GPT-5.2 Pro costs $546.00 for the same job. That's a 5.46x difference for one run. If you're calling either model at scale, this gap compounds fast — Opus 4.6 also gives you cache read at $0.50/M and cache write at $6.25/M, discounts GPT-5.2 Pro doesn't list.
Context and long-document work
Opus 4.6 handles 1,000,000 tokens of context. GPT-5.2 Pro handles 400,000 — a 2.5x gap. Both cap max output at 128,000 tokens, so the difference is entirely about how much you can stuff into the input: full repos, long transcripts, multi-document research. If your workload regularly pushes past 400K input tokens, GPT-5.2 Pro simply can't take the job in one call and you're chunking or summarizing; Opus 4.6 can ingest it whole.
Coding and agent benchmarks
Opus 4.6 has published Design Arena results across both agent and model categories: rank 3 in codecategories (elo 1342, 63.9% win rate), rank 3 in uicomponent (elo 1350, 64.5%), rank 3 in mobileapps (elo 1261, 60.5%), rank 3 in website (elo 1338, 63.3%), and rank 4 in fullstack (elo 1288, 68.6% win rate) and webapps (elo 1266, 60.9%). These are consistently top-5 placements across a dozen categories spanning agentic coding, 3D, SVG, game dev, and data visualization.
GPT-5.2 Pro has no benchmark data in this dataset. That doesn't mean it's weaker — but you can't currently point to a number to justify its 5.46x price premium over Opus 4.6 on this workload.
Reasoning controls and parameters
Opus 4.6 supports optional reasoning with four effort levels (low, medium, high, max) and defaults to medium — you can dial it down for cheap, fast calls or up for hard problems. GPT-5.2 Pro makes reasoning mandatory, with three effort levels (medium, high, xhigh) and no low-effort escape hatch, meaning every call pays the reasoning-token tax. Opus 4.6 also exposes more tunable parameters overall — top_k, top_p, verbosity, temperature — versus GPT-5.2 Pro's smaller parameter set, which lacks temperature and top_p entirely. If you need fine control over output determinism, Opus 4.6 gives you more knobs.
When to pick each
Pick Opus 4.6 by default: it's cheaper, has a larger context window, has actual benchmark evidence backing its coding and agent performance, and gives you more parameter control. Pick GPT-5.2 Pro only if you have a task where you've already confirmed OpenAI's reasoning chain outperforms Opus 4.6 in your own tests — there's no benchmark in this data to make that case for you, so don't take it on price tag alone.
Which model for which job
| Use case | Pick | Why |
|---|---|---|
| Large codebase / long document analysis | Claude Opus 4.6 | 1M token context vs 400K — 2.5x more room before you have to chunk input |
| High-volume agentic coding at scale | Claude Opus 4.6 | $100 vs $546 on a 10M-in/2M-out workload — 5.46x cheaper per run |
| Fullstack / web app generation | Claude Opus 4.6 | Ranks 4th in fullstack (elo 1288, 68.6% win rate) and 4th in webapps (elo 1266) |
| UI component generation | Claude Opus 4.6 | Ranks 3rd in uicomponent category with elo 1350, 64.5% win rate |
| Cost-sensitive prompt caching workloads | Claude Opus 4.6 | Lists cache read at $0.50/M and cache write at $6.25/M; GPT-5.2 Pro has no cache pricing listed |
| Task requiring cutting reasoning cost on simple calls | Claude Opus 4.6 | Supports a 'low' reasoning effort tier; GPT-5.2 Pro's cheapest tier is medium, with reasoning always mandatory |
Questions
- How much cheaper is Claude Opus 4.6 than GPT-5.2 Pro?
- On provider list price, Opus 4.6 is $5/M input and $25/M output versus GPT-5.2 Pro's $21/M input and $168/M output. On a workload of 10M input tokens plus 2M output tokens, Opus 4.6 costs $100.00 total and GPT-5.2 Pro costs $546.00 — a 5.46x difference.
- Which model has more context?
- Claude Opus 4.6 supports 1,000,000 tokens of context. GPT-5.2 Pro supports 400,000 tokens — a 2.5x ratio in favor of Opus 4.6. Both cap max output at 128,000 tokens, so the gap is entirely on the input side.
- Does GPT-5.2 Pro have published benchmark scores?
- No benchmark data for GPT-5.2 Pro appears in current records. Claude Opus 4.6 has Design Arena results across 12 categories, including rank 3 in codecategories (elo 1342) and rank 3 in uicomponent (elo 1350), so any performance comparison currently favors documented evidence for Opus 4.6.
- Can I use both models with one API key?
- Yes — both Claude Opus 4.6 and GPT-5.2 Pro are available on OpenKey with a single API key, and pricing is provider list price plus a flat 3% fee (e.g., Opus 4.6's $5/M input becomes $5.15/M on OpenKey).