Claude Opus 5.5 vs Claude Opus 5

Claude Opus 5.5 by Anthropic · Claude Opus 5 by Anthropic · 27 shared benchmarks

Claude Opus 5.5

78.4

#2 · 100%

Claude Opus 5

74.9

#5 · 100%

SI Score, rank and confidence side by side

Pillars — Claude Opus 5.5

Coding 72.5 / 69.7

Math 91.5 / 86.9

Preference 82.6 / 81.9

Reasoning 91.4 / 84.3

Right-hand value is Claude Opus 5.

The basics

Attribute	Claude Opus 5.5	Claude Opus 5
Input price / 1M	$4.00	$5.00
Output price / 1M	$20.00	$25.00
Context window	1M	1M
Released	Sep 22, 2026	Jul 24, 2026
Open weights	Closed	Closed

Shared benchmarks

27 in common

Only benchmarks both models have are compared. Raw values are in each benchmark's own unit; a direct comparison requires matching evaluation conditions. All reported source/variant rows are shown; no raw-result winner is assigned across unmatched harnesses. Sources and dates sit behind every dotted number.

Which should you choose?

What the data says — heuristics from the numbers above, not a verdict:

For reasoning, Claude Opus 5.5 leads by 7.0 normalized points.
For math, Claude Opus 5.5 leads by 4.6 normalized points.
Claude Opus 5.5 has the lower input-token price ($4.00 vs $5.00 per 1M).
Confidence differs: Claude Opus 5.5 100% vs Claude Opus 5 100% — pending sources can still move either score.

Benchmark	Claude Opus 5.5	Claude Opus 5	Conditions
arc agi v1 public eval	98.3%ARC Prize steward-published result; exact edition/subset; publication time is HTTP Last-Modified of the aggregate export, not the evaluation date. Evaluation conducted with 'high' reasoning effort using the standard harness. [variant] anthropic-claude-opus-5-5-high 92.3%ARC Prize steward-published result; exact edition/subset; publication time is HTTP Last-Modified of the aggregate export, not the evaluation date. Evaluation conducted with 'low' reasoning effort using the standard harness. [variant] anthropic-claude-opus-5-5-low 98.3%ARC Prize steward-published result; exact edition/subset; publication time is HTTP Last-Modified of the aggregate export, not the evaluation date. Evaluation conducted with 'max' reasoning effort using the standard harness. Partial dataset coverage: scores use full catalog denominators; costs include recorded usage only, excluding unrecorded attempts. [variant] anthropic-claude-opus-5-5-max 98.3%ARC Prize steward-published result; exact edition/subset; publication time is HTTP Last-Modified of the aggregate export, not the evaluation date. Evaluation conducted with 'medium' reasoning effort using the standard harness. [variant] anthropic-claude-opus-5-5-medium 98.6%ARC Prize steward-published result; exact edition/subset; publication time is HTTP Last-Modified of the aggregate export, not the evaluation date. Evaluation conducted with 'xhigh' reasoning effort using the standard harness. [variant] anthropic-claude-opus-5-5-xhigh	99%ARC Prize steward-published result; exact edition/subset; publication time is HTTP Last-Modified of the aggregate export, not the evaluation date. Evaluation conducted with 'high' output effort. [variant] anthropic-claude-opus-5-high 99%ARC Prize steward-published result; exact edition/subset; publication time is HTTP Last-Modified of the aggregate export, not the evaluation date. Evaluation conducted with 'max' output effort. [variant] anthropic-claude-opus-5-max	Check variant and harness
arc agi v1 semi private	98.5%ARC Prize steward-published result; exact edition/subset; publication time is HTTP Last-Modified of the aggregate export, not the evaluation date. Evaluation conducted with 'high' reasoning effort using the standard harness. [variant] anthropic-claude-opus-5-5-high 88.5%ARC Prize steward-published result; exact edition/subset; publication time is HTTP Last-Modified of the aggregate export, not the evaluation date. Evaluation conducted with 'low' reasoning effort using the standard harness. [variant] anthropic-claude-opus-5-5-low 97.5%ARC Prize steward-published result; exact edition/subset; publication time is HTTP Last-Modified of the aggregate export, not the evaluation date. Evaluation conducted with 'max' reasoning effort using the standard harness. Partial dataset coverage: scores use full catalog denominators; costs include recorded usage only, excluding unrecorded attempts. [variant] anthropic-claude-opus-5-5-max 97.5%ARC Prize steward-published result; exact edition/subset; publication time is HTTP Last-Modified of the aggregate export, not the evaluation date. Evaluation conducted with 'medium' reasoning effort using the standard harness. [variant] anthropic-claude-opus-5-5-medium 97.5%ARC Prize steward-published result; exact edition/subset; publication time is HTTP Last-Modified of the aggregate export, not the evaluation date. Evaluation conducted with 'xhigh' reasoning effort using the standard harness. [variant] anthropic-claude-opus-5-5-xhigh	97.5%ARC Prize steward-published result; exact edition/subset; publication time is HTTP Last-Modified of the aggregate export, not the evaluation date. Evaluation conducted with 'high' output effort. [variant] anthropic-claude-opus-5-high 97.5%ARC Prize steward-published result; exact edition/subset; publication time is HTTP Last-Modified of the aggregate export, not the evaluation date. Evaluation conducted with 'max' output effort. [variant] anthropic-claude-opus-5-max	Check variant and harness
arc agi v2 public eval	93.5%ARC Prize steward-published result; exact edition/subset; publication time is HTTP Last-Modified of the aggregate export, not the evaluation date. Evaluation conducted with 'high' reasoning effort using the standard harness. [variant] anthropic-claude-opus-5-5-high 67.8%ARC Prize steward-published result; exact edition/subset; publication time is HTTP Last-Modified of the aggregate export, not the evaluation date. Evaluation conducted with 'low' reasoning effort using the standard harness. [variant] anthropic-claude-opus-5-5-low 97.9%ARC Prize steward-published result; exact edition/subset; publication time is HTTP Last-Modified of the aggregate export, not the evaluation date. Evaluation conducted with 'max' reasoning effort using the standard harness. Partial dataset coverage: scores use full catalog denominators; costs include recorded usage only, excluding unrecorded attempts. [variant] anthropic-claude-opus-5-5-max 93.5%ARC Prize steward-published result; exact edition/subset; publication time is HTTP Last-Modified of the aggregate export, not the evaluation date. Evaluation conducted with 'medium' reasoning effort using the standard harness. [variant] anthropic-claude-opus-5-5-medium 97.6%ARC Prize steward-published result; exact edition/subset; publication time is HTTP Last-Modified of the aggregate export, not the evaluation date. Evaluation conducted with 'xhigh' reasoning effort using the standard harness. [variant] anthropic-claude-opus-5-5-xhigh	93.2%ARC Prize steward-published result; exact edition/subset; publication time is HTTP Last-Modified of the aggregate export, not the evaluation date. Evaluation conducted with 'high' output effort. [variant] anthropic-claude-opus-5-high 97.1%ARC Prize steward-published result; exact edition/subset; publication time is HTTP Last-Modified of the aggregate export, not the evaluation date. Evaluation conducted with 'max' output effort. [variant] anthropic-claude-opus-5-max	Check variant and harness
arc agi v2 semi private	93.3%ARC Prize steward-published result; exact edition/subset; publication time is HTTP Last-Modified of the aggregate export, not the evaluation date. Evaluation conducted with 'high' reasoning effort using the standard harness. [variant] anthropic-claude-opus-5-5-high 70.1%ARC Prize steward-published result; exact edition/subset; publication time is HTTP Last-Modified of the aggregate export, not the evaluation date. Evaluation conducted with 'low' reasoning effort using the standard harness. [variant] anthropic-claude-opus-5-5-low 91.7%ARC Prize steward-published result; exact edition/subset; publication time is HTTP Last-Modified of the aggregate export, not the evaluation date. Evaluation conducted with 'max' reasoning effort using the standard harness. Partial dataset coverage: scores use full catalog denominators; costs include recorded usage only, excluding unrecorded attempts. [variant] anthropic-claude-opus-5-5-max 87.5%ARC Prize steward-published result; exact edition/subset; publication time is HTTP Last-Modified of the aggregate export, not the evaluation date. Evaluation conducted with 'medium' reasoning effort using the standard harness. [variant] anthropic-claude-opus-5-5-medium 92.5%ARC Prize steward-published result; exact edition/subset; publication time is HTTP Last-Modified of the aggregate export, not the evaluation date. Evaluation conducted with 'xhigh' reasoning effort using the standard harness. [variant] anthropic-claude-opus-5-5-xhigh	88.3%ARC Prize steward-published result; exact edition/subset; publication time is HTTP Last-Modified of the aggregate export, not the evaluation date. Evaluation conducted with 'high' output effort. [variant] anthropic-claude-opus-5-high 90.4%ARC Prize steward-published result; exact edition/subset; publication time is HTTP Last-Modified of the aggregate export, not the evaluation date. Evaluation conducted with 'max' output effort. [variant] anthropic-claude-opus-5-max	Check variant and harness
frontiermath tier 4 v2	95%Epoch-owned evaluation mean score; scores only, no benchmark questions [variant] max	73.2%Epoch-owned evaluation mean score; scores only, no benchmark questions [variant] max	Check variant and harness
frontiermath tiers 1 3 v2	91.2%Epoch-owned evaluation mean score; scores only, no benchmark questions [variant] max	85.6%Epoch-owned evaluation mean score; scores only, no benchmark questions [variant] max	Check variant and harness
gpqa diamond	90.6%Epoch-owned evaluation mean score; scores only, no benchmark questions [variant] max	92.9%Epoch-owned evaluation mean score; scores only, no benchmark questions [variant] 87.9%Epoch-owned evaluation mean score; scores only, no benchmark questions [variant] low 93.9%Epoch-owned evaluation mean score; scores only, no benchmark questions [variant] max	Check variant and harness
hle tools	67.7%Lab-reported; metric score; transcribed by MIT models.dev catalog; not independently evaluated [variant] max effort; with tools; production safeguards with fallback	64.7%Lab-reported; metric accuracy; transcribed by MIT models.dev catalog; not independently evaluated [variant] with tools	Check variant and harness
livebench coding code completion 2026_06_25	87.0%LiveBench subtask result; dataset edition 2026_06_25; publication time is HTTP Last-Modified of the score CSV, not the dataset edition or individual evaluation date [variant] 2026_06_25	82.6%LiveBench subtask result; dataset edition 2026_06_25; publication time is HTTP Last-Modified of the score CSV, not the dataset edition or individual evaluation date [variant] 2026_06_25	Check variant and harness
livebench coding code generation 2026_06_25	91.5%LiveBench subtask result; dataset edition 2026_06_25; publication time is HTTP Last-Modified of the score CSV, not the dataset edition or individual evaluation date [variant] 2026_06_25	80.3%LiveBench subtask result; dataset edition 2026_06_25; publication time is HTTP Last-Modified of the score CSV, not the dataset edition or individual evaluation date [variant] 2026_06_25	Check variant and harness
livebench coding javascript 2026_06_25	72.7%LiveBench subtask result; dataset edition 2026_06_25; publication time is HTTP Last-Modified of the score CSV, not the dataset edition or individual evaluation date [variant] 2026_06_25	77.3%LiveBench subtask result; dataset edition 2026_06_25; publication time is HTTP Last-Modified of the score CSV, not the dataset edition or individual evaluation date [variant] 2026_06_25	Check variant and harness
livebench coding python 2026_06_25	70%LiveBench subtask result; dataset edition 2026_06_25; publication time is HTTP Last-Modified of the score CSV, not the dataset edition or individual evaluation date [variant] 2026_06_25	75%LiveBench subtask result; dataset edition 2026_06_25; publication time is HTTP Last-Modified of the score CSV, not the dataset edition or individual evaluation date [variant] 2026_06_25	Check variant and harness
livebench coding typescript 2026_06_25	53.3%LiveBench subtask result; dataset edition 2026_06_25; publication time is HTTP Last-Modified of the score CSV, not the dataset edition or individual evaluation date [variant] 2026_06_25	43.3%LiveBench subtask result; dataset edition 2026_06_25; publication time is HTTP Last-Modified of the score CSV, not the dataset edition or individual evaluation date [variant] 2026_06_25	Check variant and harness
livebench math amps hard 2026_06_25	99%LiveBench subtask result; dataset edition 2026_06_25; publication time is HTTP Last-Modified of the score CSV, not the dataset edition or individual evaluation date [variant] 2026_06_25	99.0%LiveBench subtask result; dataset edition 2026_06_25; publication time is HTTP Last-Modified of the score CSV, not the dataset edition or individual evaluation date [variant] 2026_06_25	Check variant and harness
livebench math integrals with game 2026_06_25	99%LiveBench subtask result; dataset edition 2026_06_25; publication time is HTTP Last-Modified of the score CSV, not the dataset edition or individual evaluation date [variant] 2026_06_25	97%LiveBench subtask result; dataset edition 2026_06_25; publication time is HTTP Last-Modified of the score CSV, not the dataset edition or individual evaluation date [variant] 2026_06_25	Check variant and harness
livebench math math comp 2026_06_25	97.1%LiveBench subtask result; dataset edition 2026_06_25; publication time is HTTP Last-Modified of the score CSV, not the dataset edition or individual evaluation date [variant] 2026_06_25	94.1%LiveBench subtask result; dataset edition 2026_06_25; publication time is HTTP Last-Modified of the score CSV, not the dataset edition or individual evaluation date [variant] 2026_06_25	Check variant and harness
livebench math olympiad 2026_06_25	92.2%LiveBench subtask result; dataset edition 2026_06_25; publication time is HTTP Last-Modified of the score CSV, not the dataset edition or individual evaluation date [variant] 2026_06_25	92.8%LiveBench subtask result; dataset edition 2026_06_25; publication time is HTTP Last-Modified of the score CSV, not the dataset edition or individual evaluation date [variant] 2026_06_25	Check variant and harness
livebench math simplify 2026_06_25	63%LiveBench subtask result; dataset edition 2026_06_25; publication time is HTTP Last-Modified of the score CSV, not the dataset edition or individual evaluation date [variant] 2026_06_25	61.6%LiveBench subtask result; dataset edition 2026_06_25; publication time is HTTP Last-Modified of the score CSV, not the dataset edition or individual evaluation date [variant] 2026_06_25	Check variant and harness
livebench reasoning connections 2026_06_25	99.3%LiveBench subtask result; dataset edition 2026_06_25; publication time is HTTP Last-Modified of the score CSV, not the dataset edition or individual evaluation date [variant] 2026_06_25	99.3%LiveBench subtask result; dataset edition 2026_06_25; publication time is HTTP Last-Modified of the score CSV, not the dataset edition or individual evaluation date [variant] 2026_06_25	Check variant and harness
livebench reasoning consecutive events 2026_06_25	90.4%LiveBench subtask result; dataset edition 2026_06_25; publication time is HTTP Last-Modified of the score CSV, not the dataset edition or individual evaluation date [variant] 2026_06_25	77.6%LiveBench subtask result; dataset edition 2026_06_25; publication time is HTTP Last-Modified of the score CSV, not the dataset edition or individual evaluation date [variant] 2026_06_25	Check variant and harness
livebench reasoning logic with navigation 2026_06_25	80%LiveBench subtask result; dataset edition 2026_06_25; publication time is HTTP Last-Modified of the score CSV, not the dataset edition or individual evaluation date [variant] 2026_06_25	86%LiveBench subtask result; dataset edition 2026_06_25; publication time is HTTP Last-Modified of the score CSV, not the dataset edition or individual evaluation date [variant] 2026_06_25	Check variant and harness
livebench reasoning spatial 2026_06_25	98%LiveBench subtask result; dataset edition 2026_06_25; publication time is HTTP Last-Modified of the score CSV, not the dataset edition or individual evaluation date [variant] 2026_06_25	100%LiveBench subtask result; dataset edition 2026_06_25; publication time is HTTP Last-Modified of the score CSV, not the dataset edition or individual evaluation date [variant] 2026_06_25	Check variant and harness
livebench reasoning theory of mind 2026_06_25	84.6%LiveBench subtask result; dataset edition 2026_06_25; publication time is HTTP Last-Modified of the score CSV, not the dataset edition or individual evaluation date [variant] 2026_06_25	78.8%LiveBench subtask result; dataset edition 2026_06_25; publication time is HTTP Last-Modified of the score CSV, not the dataset edition or individual evaluation date [variant] 2026_06_25	Check variant and harness
livebench reasoning zebra puzzle 2026_06_25	100%LiveBench subtask result; dataset edition 2026_06_25; publication time is HTTP Last-Modified of the score CSV, not the dataset edition or individual evaluation date [variant] 2026_06_25	100%LiveBench subtask result; dataset edition 2026_06_25; publication time is HTTP Last-Modified of the score CSV, not the dataset edition or individual evaluation date [variant] 2026_06_25	Check variant and harness
lmarena text	1511.7 eloPublished source fact [variant] text / overall	1502.1 eloPublished source fact [variant] text / overall	Check variant and harness
otis mock aime 2024 2025	100%Epoch-owned evaluation mean score; scores only, no benchmark questions [variant] max	97.8%Epoch-owned evaluation mean score; scores only, no benchmark questions [variant] 93.3%Epoch-owned evaluation mean score; scores only, no benchmark questions [variant] low 98.9%Epoch-owned evaluation mean score; scores only, no benchmark questions [variant] max	Check variant and harness
terminal bench v4 0	66.4%Lab-reported; metric score; transcribed by MIT models.dev catalog; not independently evaluated [variant] xhigh effort; production safeguards with fallback; 4.0 64.8%Terminal-Bench 4.0; published harness submission, 95% CI retained at source [variant] Claude Code; max	50.3%Terminal-Bench 4.0; published harness submission, 95% CI retained at source [variant] Claude Code; high 34.9%Terminal-Bench 4.0; published harness submission, 95% CI retained at source [variant] Claude Code; low 51.8%Terminal-Bench 4.0; published harness submission, 95% CI retained at source [variant] Claude Code; max 44.9%Terminal-Bench 4.0; published harness submission, 95% CI retained at source [variant] Claude Code; medium 53.9%Terminal-Bench 4.0; published harness submission, 95% CI retained at source [variant] Claude Code; xhigh	Check variant and harness