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A · closed · Claude Opus

Claude Opus 4.8

Anthropic

B · closed · GPT-5.x

GPT-5.5

OpenAI

7:11

overall capability wins (1 ties across 19 scored). GPT-5.5 leads overall.

  • Reasoning1:5
  • Coding4:3
  • Arena0:1
  • Agents1:0
  • Tool use1:1
  • Composite indices2:0
  • Pricing2:0
  • Speed1:1
  • Specs0:1

Verdict

Claude Opus 4.8 leads coding (widest gap: +28.7 on WebDev Elo); GPT-5.5 edges reasoning & knowledge; GPT-5.5 offers larger context (1.1M vs 1M).

  • Claude Opus 4.8 leads coding (widest gap: +28.7 on WebDev Elo)
  • GPT-5.5 edges reasoning & knowledge
  • GPT-5.5 offers larger context (1.1M vs 1M)

Cost for 1M in + 250K out

Illustrative chat workload at primary-provider list prices.

Claude Opus 4.8
$11.25
GPT-5.5
$12.50

Claude Opus 4.8 is about 1.1x cheaper on this workload.

Price per 1M tokens

Full comparison

Organization

Anthropic

OpenAI

Family

Claude Opus

GPT-5.x

License

Proprietary

Proprietary

Open weights

No

No

Release

May 28, 2026

Apr 23, 2026

Knowledge cutoff

-

-

API / provider

Anthropic

OpenAI

Modalities

text, image → text

text, image → text

Specs

Context window

1M

1.1M

B +50K

Max output

128K

128K

tie

Parameters

—

—

—

Pricing

Input $/1M

$5

$5

tie

Output $/1M

$25

$30

A +$5

Blended $/1M (3∶1)

$10

$11.25

A +$1.25

Speed

tok/s

72

70

A +2.00

TTFT (s)

0.55

0.5

B +0.05

Reasoning

MMLU-Pro

—

—

—

GPQA Diamond

92.0

93.5

B +1.5 pts

Humanity's Last Exam

48.7

45.8

A +2.9 pts

AIME 2025

—

—

—

MATH-500

—

—

—

Humanity's Last Exam (with tools)

—

—

—

AA-Omniscience Accuracy

48.8

58.0

B +9.2 pts

AA-LCR v1.1

77.7

84.3

B +6.6 pts

CritPt

20.9

27.1

B +6.2 pts

MMMU-Pro

—

79.9

—

IFBench

62.2

75.9

B +13.7 pts

Chartography

—

—

—

Chartography (With Tools)

—

—

—

Coding

SWE-bench Verified

—

—

—

SWE-bench Pro

69.2

58.6

A +10.6 pts

SWE-bench Multilingual

—

—

—

LiveCodeBench

—

—

—

Terminal-Bench 2.1

84.6

84.3

A +0.3 pts

Aider Polyglot

—

—

—

Terminal-Bench 3

21.1

—

—

BigCodeBench

—

—

—

SciCode

54.4

55.8

B +1.4 pts

CursorBench

62.3

58.4

A +3.9 pts

SWE-Rebench

56.5

62.7

B +6.2 pts

NL2Repo-Bench

—

—

—

DeepSWE

59.0

67.0

B +8.0 pts

WebDev Arena

1,539

1,510

A +29 Elo

Terminal-Bench 4.0

23.6

—

—

CursorBench 4.0

—

—

—

FrontierCode v1.1 (Main)

—

—

—

Arena

LMArena Elo

1,473

1,476

B +3 Elo

Claude Opus 4.8

Context
1M / 128K out
Parameters
—
Price
$5 / $25
Speed
72 tok/s · 0.55s TTFT
Modalities
text, image → text
License
Proprietary

Previous Opus flagship with 1M context; still competitive for coding agents and computer use.

GPT-5.5

Context
1.1M / 128K out
Parameters
—
Price
$5 / $30
Speed
70 tok/s · 0.5s TTFT
Modalities
text, image → text
License
Proprietary

Prior OpenAI flagship with strong coding and long context; still widely used alongside the newer 5.6 family.

Benchmark charts

Winner bars are emphasized. Per-benchmark deltas sit above each chart.

Reasoning & knowledge

GPQA: B +1.5HLE: A +2.9CritPt: B +6.2AA-LCR: B +6.6Omniscience Acc.: B +9.2IFBench: B +13.7

Coding

SWE-Pro: A +10.6TermBench: A +0.3SciCode: B +1.4CursorBench: A +3.9SWE-Rebench: B +6.2DeepSWE: B +8.0WebDev Elo: A +29

Tool use & function calling

Toolathlon V.: A +2.7τ³-Banking: B +4.8

Agents & computer use

GDPval-AA: A +96

Arena

Arena Elo: B +3

Composite indices

AA Index: A +3.4AA Index v4.3: A +3.4

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