Claude Opus vs GPT-5 in 2026: Opus 4.8 vs GPT-5.5 Tested

Claude Opus vs GPT-5 in 2026: Opus 4.8 vs GPT-5.5 Tested

The “Claude Opus 4.1 vs GPT-5” matchup people still search for is two Anthropic releases and one government ban out of date. Opus 4.1 shipped in August 2025 at $75 per million output tokens; the current flagship, Opus 4.8, costs $25 and Anthropic’s most capable model after it, Fable 5, was disabled worldwide by a US export-control order three days after launch, and back online since 1 July (Anthropic, 2026). So the real question in mid-2026 isn’t 4.1 versus the original GPT-5. It’s Claude Opus 4.8 versus GPT-5.5, and the answer is closer on price and wider on capability than the old comparisons suggest. I’ve run both as daily drivers, and here’s where each one actually wins.

Key Takeaways

• The current matchup is Claude Opus 4.8 (released 28 May 2026) versus GPT-5.5 (released 23 April 2026), not Opus 4.1 versus the first GPT-5. Both old version numbers are retired.
• Opus 4.8 leads on 8 of the 9 head-to-head benchmarks I could source, including reasoning, agentic tool use, and long context. GPT-5.5’s one clean win is Terminal-Bench 2.0 (DataCamp, 2026).
• The “Anthropic is more expensive” rule no longer holds at the top tier: input is identical ($5) and Opus 4.8 output ($25) is actually cheaper than GPT-5.5 ($30). The premium shows up at the mid and Pro tiers.
• For me, the deciding factor is reliability on long agentic runs plus the Claude Code workflow, not a benchmark.

Claude Opus vs GPT-5: the 2026 matchup at a glance

The short version: Claude Opus 4.8 is the more capable model in mid-2026, GPT-5.5 is close behind and competitive on terminal coding, and the two are roughly at price parity at the flagship tier. Opus 4.8 posts a 61.4 on the Artificial Analysis Intelligence Index against 60.2 for GPT-5.5, and leads on the harder agentic and reasoning evals (Artificial Analysis, 2026). Neither is a runaway. This is the tightest the frontier has been.

Here’s the spec sheet for the two current flagships, side by side.

Sources: Anthropic and OpenAI developer docs for pricing and context; DataCamp and Artificial Analysis for benchmarks, 2026.

Put four headline benchmarks next to each other and the pattern is consistent: Opus is ahead, usually by a few points, occasionally by a lot.

Source: DataCamp and Artificial Analysis head-to-head, 2026. Scores are out of 100.

Which versions are we actually comparing?

If you searched “claude opus 4.1 vs gpt 5” or “claude sonnet 4.5 vs gpt 5,” you were comparing models that have already been replaced. Both labs shipped fast in late 2025 and early 2026, and the version you remember is probably two or three releases behind. Here’s the timeline so you can map any old comparison to the current one.

Sources: Anthropic and OpenAI release notes, 2026.

The single most useful thing to take from that table: Anthropic’s flagship got cheaper while OpenAI’s got more expensive. Opus dropped from $15 to $5 input between 4.1 and 4.5, and GPT-5 climbed from $1.25 to $5 between the original and 5.5. The old “Claude costs three times more” reflex is from the Opus 4.1 era. It doesn’t describe 2026.

One more thing the version churn hides: the GPT-5 you read about at launch and the GPT-5.5 you call today are not the same model with a bigger number. OpenAI folded its separate Codex coding line back into the main model across the 5.x releases, which is part of why GPT-5.5 is so strong in the terminal specifically. If a year-old “GPT-5 is weak at agentic coding” take is shaping your choice, throw it out. That gap closed.

Benchmarks: where Opus 4.8 leads and where GPT-5.5 wins

Across the nine head-to-head benchmarks in DataCamp’s side-by-side, Opus 4.8 wins eight and GPT-5.5 wins one (DataCamp, 2026). That sounds lopsided, and on reasoning and tool use it is: Opus leads Humanity’s Last Exam by 8 points without tools, leads the MCP-Atlas tool-use eval 82.2 to 75.3, and stretches its lead on long-context retrieval as the window grows. But a clean sweep would be a red flag, and this isn’t one.

Source: DataCamp Opus 4.8 vs GPT-5.5 head-to-head, 2026.

GPT-5.5’s win is Terminal-Bench 2.0, where it scores 78.2 to Opus 4.8’s 74.6 (DataCamp, 2026). That’s not a footnote. Terminal-Bench measures exactly the kind of shell-driven, run-the-command-and-read-the-output work that fills a real coding session, and GPT-5.5 is genuinely good at it. So the honest read is: Opus is the stronger reasoner and the more reliable agent over long horizons, while GPT-5.5 is right there with it on hands-on terminal coding and ahead on that one eval.

Two cautions on the numbers. First, I’m deliberately not quoting a SWE-bench Verified figure for GPT-5.5, because that benchmark’s scores are contested across leaderboards and OpenAI’s own pages were unreachable when I checked. SWE-bench Pro, the harder contamination-resistant set, is the cleaner comparison. Second, neither lab published a clean GPQA or AIME head-to-head between these two models, so anyone showing you one is reconstructing it. For a deeper look at how coding benchmarks get contaminated and why I read them as ceilings rather than rankings, see my guide to the best LLM for coding, including why SWE-bench Verified broke.

Is Claude Opus more expensive than GPT-5?

Not at the flagship tier, and this surprises people. Opus 4.8 and GPT-5.5 charge the same $5 per million input tokens, and Opus is actually cheaper on output at $25 versus GPT-5.5’s $30 (Anthropic and OpenAI, 2026). The “Anthropic premium” is real, but it lives at the other tiers, not the top one.

Source: Anthropic and OpenAI pricing pages, 2026. Teal is Anthropic, orange is OpenAI.

Where Anthropic does cost more is at the extremes. Its mid-tier Sonnet 4.6 runs $3 input against GPT-5.4’s $2.50, and its most capable model, Fable 5, is priced at $10 / $50, well above any Opus tier. OpenAI’s answer at the very top is GPT-5.5 Pro at a steep $30 / $180 (OpenAI, 2026), so “who is more expensive” genuinely depends on which rung you’re standing on. The fair summary: roughly at parity for the flagships, OpenAI a little cheaper at the small end, and both labs charging a lot for their absolute top model. If cost is your main lever, the more interesting comparison isn’t Claude versus GPT-5 at all, it’s either of them against the open-weight field in my roundup of the best open-source LLMs, or the version question in DeepSeek R1 versus V3 compared.

Where Opus pulls ahead in my testing

Benchmarks get you to the door. What decides it for me is what happens on a real, hour-long agentic task, and there Opus 4.8 has been the model I trust not to lose the thread.

The difference I notice most isn’t raw smarts, it’s omission. On a long multi-step job, GPT-5.5 is fast and mostly right, but it occasionally drops a detail: a file it was supposed to also update, an edge case from three messages back, a constraint I stated once. Opus 4.8 is the one I catch doing that least often. On the kind of task where a single missed step means a broken build and a debugging session, “rarely forgets” beats “slightly faster,” and that’s the trade I keep making. I’m not claiming Opus is flawless. I’m saying that in my setup it’s the model I hand the work I can’t afford to re-check line by line.

The other half of my answer isn’t the model at all, it’s the harness around it. Opus paired with Claude Code, Anthropic’s own agentic coding tool, is where the model’s long-horizon reliability actually pays off, because the tool is tuned for the exact plan-edit-test-recover loop Opus is good at. GPT-5.5 is strong, and OpenAI’s own coding tooling has caught up a lot, but the Claude Code combination is still the one I reach for on serious work. That’s a tooling comparison, though, not a model one, and it deserves its own treatment: I keep this article on the raw models and send the command-line fight to my Claude Code versus Codex CLI comparison. For what the Claude Code tiers actually cost, the breakdown is in my Claude Code pricing and limits guide.

One boundary worth stating plainly, because the search terms blur it: this is a comparison of the models you call through an API, not the command-line agents built on them. “GPT-5 vs Claude Code” is a different question, because it pits a model against a tool. Keep the two separate and you’ll make a better decision.

The model that was too capable to keep online

Here’s the part of the Anthropic story that has no OpenAI equivalent in 2026, and it’s the clearest signal of where the frontier sits. On 9 June 2026, Anthropic launched Claude Fable 5 and a less-restricted sibling, Claude Mythos 5, as its most capable models yet. Three days later, on 12 June, it disabled both worldwide, for every user including its US customers, after a US government export-control directive (Anthropic, 2026).

The trigger, as reported, was that the government believed Fable 5’s cybersecurity safeguards could be jailbroken, and it moved to restrict the model itself. It’s the first time US export controls were applied to an AI model rather than to chips (TechCrunch, 2026). Anthropic publicly disagreed, calling the jailbreak narrow and already reproducible with other public models, and said it was working to restore access (Tom’s Hardware, 2026). Commerce lifted the order on 30 June, and Anthropic restored Fable 5 worldwide, including inside Claude Code, on 1 July (Anthropic, 2026).

Set the policy fight aside and look at what it tells you about the comparison. Anthropic shipped a model capable enough that a government treated it like a controlled weapons technology, then pulled it within days. That’s not a normal release cadence, and it’s worth weighing if you’re betting on a vendor: it’s a sign of how close to the edge Anthropic is pushing, and also a reminder that its very top tier can be less predictable to rely on than a stable flagship. For everyday work, that’s why Opus 4.8, the mainstream flagship, is the right Anthropic model to compare against GPT-5.5, rather than the headline-grabbing top tier, which is back online but priced for the hardest jobs only.

Claude Opus vs GPT-5: which should you pick?

There’s no universal winner here, only a better fit per job. After living in both, this is how I’d route the decision between the current flagships.

• Long, autonomous agentic runs and hard reasoning: Claude Opus 4.8. It’s the model I trust to hold a multi-step task together without dropping a detail.
• Fast terminal coding and shell-heavy loops: GPT-5.5 is genuinely competitive and wins Terminal-Bench 2.0. If your day is mostly command-line work, try it head to head before assuming Opus.
• Tightest budget at the flagship tier: Opus 4.8, narrowly, on output price. But the gap is small enough that capability should decide it.
• Absolute maximum capability, cost no object: Anthropic’s Fable 5 is back online at $10 / $50, double Opus 4.8; OpenAI’s GPT-5.5 Pro is priced at $30 / $180. For most people the standard flagships are still the smarter buy, but if you want to know when Fable’s premium is worth it, I break it down in my guide to running Fable 5 in Claude Code.
• You mostly write code: don’t pick on a “vs” article alone. Models behave differently across languages and task types, which I break down in my best-LLM-for-coding ranking.

Notice that I don’t route everything to one model, and neither should you. What actually matters in 2026 isn’t finding the single best LLM, it’s matching the model to the task, which is how I work day to day, described in my multi-model workflow across Claude, ChatGPT, and Gemini.

Frequently asked questions

Is Claude Opus better than GPT-5 in 2026?

In most respects, yes. Claude Opus 4.8 leads GPT-5.5 on 8 of 9 head-to-head benchmarks, including reasoning and agentic tool use, and posts a 61.4 to 60.2 on the Artificial Analysis Intelligence Index (Artificial Analysis, 2026). GPT-5.5 wins on Terminal-Bench 2.0, so it’s close on hands-on terminal coding.

Claude Opus 4.1 vs GPT-5: which is newer?

Both are outdated labels. Opus 4.1 shipped in August 2025 and has been replaced by Opus 4.5, 4.6, 4.7, and now Opus 4.8 (28 May 2026). The original GPT-5 from August 2025 has been superseded by the 5.x line up to GPT-5.5 (23 April 2026). Compare Opus 4.8 against GPT-5.5 instead.

Is GPT-5 cheaper than Claude Opus?

Not at the flagship tier. GPT-5.5 and Opus 4.8 both cost $5 per million input tokens, and Opus is cheaper on output at $25 versus $30 (OpenAI, 2026). OpenAI is slightly cheaper at the small-model tier, and both labs charge a premium for their top “Pro” or most-capable model.

Claude Sonnet 4.5 vs GPT-5: how do they compare?

Sonnet 4.5 was Anthropic’s speed-to-intelligence pick from the Claude 4 line, but it has been replaced by Sonnet 4.6. The current mid-tier matchup is Sonnet 4.6 ($3 / $15) against GPT-5.4 ($2.50 / $15). For most flagship comparisons, use Opus 4.8 versus GPT-5.5.

Which is better for coding, Claude Opus or GPT-5?

It splits. Opus 4.8 leads on hard, multi-file agentic coding (SWE-bench Pro 69.2% versus 58.6%), while GPT-5.5 edges ahead on terminal workflows. Pick by the shape of your work rather than a single benchmark.

What happened to Claude Fable 5?

Anthropic launched Fable 5 and Mythos 5 on 9 June 2026 and disabled both worldwide on 12 June after a US export-control directive over the model’s cybersecurity capabilities, the first export control applied to an AI model itself (Anthropic, 2026). Commerce lifted the order on 30 June, and Fable 5 returned to Claude.ai, the API, and Claude Code on 1 July (Anthropic, 2026).

The verdict

Claude Opus 4.8 is the model I’d pick over GPT-5.5 in mid-2026, and the reason isn’t a benchmark, it’s that on long, high-stakes work it forgets less and holds the thread better, and the Claude Code workflow turns that reliability into finished output. But this is the closest the gap has ever been. GPT-5.5 matches Opus on price at the flagship tier, beats it on Terminal-Bench, and is the better-known quantity right now, even with Anthropic’s top tier, Fable 5, back online at a steep premium. If you mostly live in the terminal, test GPT-5.5 against Opus on your own work for a week before you assume Opus wins. If you want one model for hard agentic runs and you value rarely-wrong over slightly-faster, Opus 4.8 is the pick. And if your real question is which to run for cost or privacy, start one tier down with my complete guide to running LLMs locally before paying for either frontier API.