AI Flash Report

Claude Opus 4.8 vs GPT-5.3 Codex: Benchmarks, Pricing & Capabilities Compared

TL;DR — Claude Opus 4.8 wins for long-context · GPT-5.3 Codex wins for cost.

Claude Opus 4.8 Anthropic
Released
2026-05-28
Context window
1M tokens
Input price
$6.25 / Mtok
Output price
$25.00 / Mtok
GPT-5.3 Codex OpenAI
Released
2026-02-05
Context window
400K tokens
Input price
$1.25 / Mtok
Output price
$10.00 / Mtok
Key features
  • Self-improving agentic coding
  • 25% faster than GPT-5.2-Codex
  • 1,000+ tokens/sec generation

Benchmark comparison

Benchmark Claude Opus 4.8 GPT-5.3 Codex
GPQA Diamond 92.0% ✓ 91.5%
HLE 45.7% ✓ 39.9%
IF-Bench 62.2% 75.4% ✓
LiveCodeBench Reasoning 67.7% 74.0% ✓
SciCode 53.5% ✓ 53.2%
TAU2-bench 94.4% ✓ 86.0%
TerminalBench-Hard 58.3% ✓ 53.0%

Pricing comparison

Metric Claude Opus 4.8 GPT-5.3 Codex
Input ($/Mtok) $6.25 $1.25
Output ($/Mtok) $25.00 $10.00
Cached input ($/Mtok) — $0.13
Cost per 1M-token roundtrip (1M in + 1M out) $31.25 $11.25

Context window & modalities

Attribute Claude Opus 4.8 GPT-5.3 Codex
Context window 1M tokens 400K tokens
Input modalities text, image text, image
Output modalities text text
Knowledge cutoff — 2025-11

Verdict by use case

Coding
Insufficient data
Basis: SWE-bench

No shared coding benchmark.

Reasoning
→ Claude Opus 4.8
Basis: GPQA Diamond

Claude Opus 4.8 92% vs GPT-5.3 Codex 91.5% on GPQA Diamond.

Math
Insufficient data
Basis: MATH / AIME

No shared math benchmark.

Long context
→ Claude Opus 4.8
Basis: Context window

Claude Opus 4.8 1M tokens vs GPT-5.3 Codex 400K tokens.

Cost
→ GPT-5.3 Codex
Basis: Input $/Mtok

Claude Opus 4.8 $6.25/Mtok vs GPT-5.3 Codex $1.25/Mtok input.

Changelog & releases

Claude Opus 4.8
Released 2026-05-28
GPT-5.3 Codex
Released 2026-02-05
Predecessor: openai-gpt-5-2-codex
  • +4pt on SWE-bench Verified vs GPT-5.2 Codex
  • Native IDE tool-calling at reduced latency
  • Extended max output to 100K for multi-file patches

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