All benchmarks

Head-to-head analysis

Claude Opus 4.8 vs GPT-5.5

Blind preference, cited external data, live API pricing, and observed evaluation latency in one auditable view.

Pair votes0
Cited sources1
PublicationQualified

Comparison matrix

Signal, speed, and price.

Metric
Claude Opus 4.8
GPT-5.5
Combined quality
91.5
95.5
Arena score
51.2
Pending
External score
94.5
95.5
Median latency
11889ms
Pending
Input / 1M
$5
$5
Output / 1M
$25
$30
Context
1M
256K

Blind preference.

No direct RouterPlex Arena votes are published for this pair yet. The quality comparison currently relies on the cited external snapshot below.

Decision note.

GPT-5.5 currently leads the combined quality signal. That does not settle every workload: compare category results, token price, and observed latency before choosing.

Evidence ledger

Source and freshness.

External scores preserve the original rating, rank, vote count, and confidence interval. RouterPlex converts source rank to a within-category percentile for the common 0-100 display scale.

LMArena Text Leaderboard

2026-08-03 text_style_control 0fdff69b4fd7 / 2026-08-07

Bradley-Terry ratings from LMArena's style-controlled text leaderboard. RouterPlex preserves the raw rating, source rank, confidence interval, vote count, and publish date. The displayed external score is the source-rank percentile within each source category.

LMArena leaderboard dataset, licensed CC BY 4.0. RouterPlex includes only exact case-insensitive model-ID matches. Official leaderboard: https://arena.ai/leaderboard. Dataset: https://huggingface.co/datasets/lmarena-ai/leaderboard-dataset. Dataset commit: 4e52c8e709c90a4cad8498d9db5aad11709b04e0. LMArena is not affiliated with RouterPlex.

Your prompt, blind result

Put both models on the same task.

RouterPlex reveals the model names only after your vote.

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Claude Opus 4.8 vs GPT-5.5: Benchmarks · RouterPlex