Claude Sonnet 4.5
VS
GPT-5.5
Claude Sonnet 4.5 vs GPT-5.5: which wins at real work?
22 task areas · same graded test runs · rank comparison only, so 0–100 and Elo collections never mix raw scores.
GPT-5.5 wins 18 of 22 task areas we tested; Claude Sonnet 4.5 takes 4. Claude Sonnet 4.5 costs 1.9× less per token ($18 vs $35 per 1M).
Claude Sonnet 4.5 costs 1.9× less per token ($18 vs $35 per 1M).
Task by task
| Task area | Claude Sonnet 4.5 | GPT-5.5 | Winner |
|---|---|---|---|
| Structured Output |
#80
/ 113
Strong
|
#3
/ 113
Excellent
|
GPT-5.5 |
| Chef / Home Cooking |
#80
/ 126
Usable
|
#4
/ 126
Strong
|
GPT-5.5 |
| Content & Brand |
#74
/ 124
Usable
|
#4
/ 124
Strong
|
GPT-5.5 |
| Creative & Comedy | #66 / 110 | #2 / 110 | GPT-5.5 |
| Product & Project Management |
#71
/ 110
Strong
|
#8
/ 110
Excellent
|
GPT-5.5 |
| Coding |
#62
/ 115
Strong
|
#1
/ 115
Excellent
|
GPT-5.5 |
| Legal & HR |
#69
/ 110
Strong
|
#9
/ 110
Excellent
|
GPT-5.5 |
| Customer Support |
#43
/ 113
Strong
|
#3
/ 113
Strong
|
GPT-5.5 |
| Presentations & Decks |
#43
/ 110
Excellent
|
#3
/ 110
Excellent
|
GPT-5.5 |
| Research & Competitive Analysis |
#39
/ 110
Strong
|
#7
/ 110
Excellent
|
GPT-5.5 |
| Sales |
#10
/ 110
Strong
|
#42
/ 110
Usable
|
Claude Sonnet 4.5 |
| Investor & Pitch |
#42
/ 66
Usable
|
#16
/ 66
Strong
|
GPT-5.5 |
| Knowledge & Docs |
#28
/ 110
Strong
|
#5
/ 110
Excellent
|
GPT-5.5 |
| RAG, Safety & Grounding |
#39
/ 113
Excellent
|
#16
/ 113
Excellent
|
GPT-5.5 |
| Translation & Localization |
#25
/ 110
Excellent
|
#3
/ 110
Excellent
|
GPT-5.5 |
| Landing Pages |
#30
/ 72
Strong
|
#9
/ 72
Strong
|
GPT-5.5 |
| Executive Assistant |
#31
/ 112
Strong
|
#11
/ 112
Strong
|
GPT-5.5 |
| Frontend & Landing Pages |
#29
/ 109
Needs editing
|
#13
/ 109
Needs editing
|
GPT-5.5 |
| Data & Analytics |
#33
/ 110
Excellent
|
#48
/ 110
Excellent
|
Claude Sonnet 4.5 |
| Training & Education |
#51
/ 110
Excellent
|
#63
/ 110
Excellent
|
Claude Sonnet 4.5 |
| Summarization & Meeting Notes |
#2
/ 110
Excellent
|
#10
/ 110
Excellent
|
Claude Sonnet 4.5 |
| AI Strategy |
#67
/ 126
Strong
|
#62
/ 126
Strong
|
GPT-5.5 |
Rank = position among every model config we tested in that task area (lower is better). Sorted by biggest gap first.
Same task, both models — judged
Both models answered the same test case; an independent judge graded each. Quotes are the judge's actual rationale.
Content & Brand
Founder newsletter intro about product lessons (Generic Copy Index)
“The response invents highly specific facts and fabricated anecdotes not present in the brief, requiring heavy editing.”
“The response perfectly executes the prompt, adhering to all constraints. It provides a highly specific, non-obvious lesson with realistic, technical examples. The tone is authentic and punchy, with zero generic filler.”
Frequently asked
Is Claude Sonnet 4.5 better than GPT-5.5?
Across 22 task areas we benchmarked, GPT-5.5 ranks higher in 18 and Claude Sonnet 4.5 in 4.
Which is cheaper, Claude Sonnet 4.5 or GPT-5.5?
Claude Sonnet 4.5 costs 1.9× less per token ($18 vs $35 per 1M).
What is Claude Sonnet 4.5 better at?
Claude Sonnet 4.5 out-ranks GPT-5.5 at Sales, Data & Analytics, Training & Education.
What is GPT-5.5 better at?
GPT-5.5 out-ranks Claude Sonnet 4.5 at Structured Output, Chef / Home Cooking, Content & Brand.
More comparisons
This page is Spring Prompt, running in public
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Prompt × model results
12 test cases · 3 evals