Which is better, Claude Opus 4.8 or Claude Sonnet 4.5?

Across 45 shared benchmarks tracked on Vector Wire, Claude Opus 4.8 leads on 43 and Claude Sonnet 4.5 leads on 2 — Claude Opus 4.8 leads on more. Strengths differ by axis; the table below shows every head-to-head number with provenance.

SEEDRefresh Models —Deals —Regulatory —Sources —

Claude Opus 4.8 vs Claude Sonnet 4.5

AnthropicvsAnthropic45 shared benchmarks43–2 head-to-head

Benchmark	Claude Opus 4.8	Claude Sonnet 4.5
AA Agentic Index	49.4	50.6
AA Intelligence	57.3	37.4
AA-LCR	73	68.3
AA-Omniscience	28.8	-0.1
arc_agi_1	92.5	63.7
ARC-AGI-2	72.1	13.6
arena_elo	1482	1456
arena_text_factuality	1464	1448
Artificial Analysis Coding Index	74.3	52.1
browsecomp	88.5	24.1
charxiv_rq	80.5	67.2
coding_arena_elo	1539	1392
critpt	20.9	1.1
Fortress	18.2	17
frontiermath_tier_4	31.3	4.2
gdpval	54.2	40.4
GPQA Diamond	93.6	83.4
HealthBench	59.3	44.2
HLE	57.9	19.8
HLE (with tools)	57.9	32
hmmt_nov_2025	96.5	81.7
IFBench	62.2	57.3
imo_answer_bench	83.5	65.9
longbench_v2	69.1	61.8
matharena_visual_math_overall	81.6	75.8
MCP Atlas	83.6	59.5
MMMU-Pro	78.9	68.7
OmniScience Accuracy	48.8	32.9
OmniScience Non-Hallucination	60.7	50.9
OSWorld-Verified	83.4	61.4
scicode	53.5	45
simplebench	64.8	54.3
simpleqa_verified	39.5	23.6
SWE-bench Multilingual	84.4	68
SWE-bench Pro	69.2	43.6
SWE-bench Verified	88.6	82
TauBench V3 - Banking	34.2	24.5
Terminal-Bench 2.0	74.6	50
Terminal-Bench 2.1	85	55.8
Terminal-Bench Hard	58.3	35.6
toolathlon	59.9	41
Toolathlon Avg turns	24.5	32
Toolathlon Pass@∞	48.1	28.7
τ²-Bench Telecom (AA run)	94.4	78.1
τ³-Bench	27.6	19

Best tracked score per model per benchmark (default configuration; source-attributed). ↓ marks lower-is-better metrics. Open either model for its full surface, provenance and pricing.