Capability · Comparison
Claude 3 Opus vs GPT-4o
Claude 3 Opus (Anthropic, March 2024) and GPT-4o (OpenAI, May 2024) were the two dominant frontier models of 2024. Both are now legacy — Claude 4.7 and GPT-5 have long surpassed them — but many production systems still run on them. This comparison is primarily for teams deciding whether to migrate, and which direction to go.
Side-by-side
| Criterion | Claude 3 Opus | GPT-4o |
|---|---|---|
| Release | March 2024 | May 2024 |
| Context window | 200k tokens | 128k tokens |
| Multimodal | Text + vision | Text + vision + audio (native) |
| MMLU | ≈86.8% | ≈88.7% |
| Writing quality (human pref) | Leader in 2024 | Close second |
| Pricing ($/M input) | $15 | $5 (at deprecation) |
| Status in 2026 | Legacy — superseded by Opus 4.x | Legacy — superseded by GPT-4.1 / GPT-5 |
| Tool use reliability | Good for 2024 | Better for 2024, especially structured outputs |
Verdict
Both are legacy. For new builds, do not choose either — go Claude Opus 4.7 / Sonnet 4.6 or GPT-5 / GPT-5 Mini. For existing systems: Claude 3 Opus users migrate upward to Claude Sonnet 4.6 (cheaper, stronger) or Opus 4.7 (same family, much better). GPT-4o users migrate to GPT-4.1 for a drop-in upgrade or GPT-5 for a real capability jump. Do not migrate Claude 3 Opus to GPT-4o or vice versa in 2026 — that's a sideways move.
When to choose each
Choose Claude 3 Opus if…
- Only if you're pinned to Claude 3 Opus for eval/compliance reasons.
- You need the 200k window and can't upgrade yet.
- You're stuck on a Bedrock region that hasn't rolled Opus 4.x yet.
- Otherwise: upgrade to Sonnet 4.6 or Opus 4.7.
Choose GPT-4o if…
- Only if you're pinned to GPT-4o for eval stability.
- You need the native audio features that GPT-4.1 initially lacked.
- Legacy Assistants API workloads that haven't migrated.
- Otherwise: upgrade to GPT-4.1 or GPT-5.
Frequently asked questions
Should I still start a new project on Claude 3 Opus or GPT-4o?
No. Both are legacy and slower/costlier than their successors for equivalent quality. New projects should start on Claude Sonnet 4.6 / Opus 4.7 or GPT-5 / GPT-5 Mini.
What's the equivalent of Claude 3 Opus in 2026?
Claude Sonnet 4.6 matches or exceeds Claude 3 Opus on almost all benchmarks at roughly a third of the cost. Claude Opus 4.7 is the direct successor at the top of the family.
What's the equivalent of GPT-4o in 2026?
GPT-4.1 is the direct drop-in upgrade. GPT-5 is the current flagship. GPT-5 Mini is roughly GPT-4o-tier quality at much lower cost and latency.
Sources
- Anthropic — Model deprecations — accessed 2026-04-20
- OpenAI — Models — accessed 2026-04-20