Claude Mythos 5 wins on coding (100 vs 96). GPT-5.5 wins on price ($5 vs $10/1M input). For most workflows, Claude Mythos 5 is the stronger default — superseded by mythos 5.1 — same model as fable 5, safeguards lifted, partner-only.
The safest Claude Mythos 5 vs GPT-5.5 default, the cheaper option worth trying first, and the specialist pick — before you read the detail below.
Claude Mythos 5 is the strongest answer here for Claude Mythos 5 vs GPT-5.5 — pick it when quality of output matters more than the $10.00/1M/1M input you pay for it.
GPT-5.5 handles the same job for about 42% less per token. Start here and only move up if the output is not good enough.
GPT-5.5 is the fastest of these for Claude Mythos 5 vs GPT-5.5 — worth it when latency is what the reader notices, not the last few points of reasoning depth.
Claude Mythos 5 leads on coding with a score of 100 vs 96 for GPT-5.5.
GPT-5.5 is cheaper at $5/1M input tokens vs $10/1M for Claude Mythos 5.
Claude Mythos 5 is the stronger default for coding tasks.
Go with Claude Mythos 5 if you want one model to handle coding and research — it targets frontier cybersecurity research, autonomous vulnerability discovery, and the absolute capability ceiling.
Switch to GPT-5.5 when your work is mostly agentic coding and computer-use workflows; on that narrower brief it is the better tool.
GPT-5.5 is the more cost-efficient option at $5/1M input — Claude Mythos 5 costs 2x more per input token, so the gap is worth taking seriously wherever token volume rather than peak quality drives the bill.
Switch the scoring lens to see whether the Claude Mythos 5 vs GPT-5.5 answer changes when cost, speed, or long-document depth leads the decision.
Anthropic / Premium / Jun 9, 2026
The frontier ceiling — same model as Fable 5, safeguards lifted, partner-only.
Ranks models by the broadest mix of coding, writing, research, and long-context usefulness.
You don't have vetted-partner access or don't need lifted safeguards — Fable 5 is the same model, generally available, at the same price.
Where the Claude Mythos 5 vs GPT-5.5 recommendation shifts once you weigh price or latency differently.
The frontier ceiling — same model as Fable 5, safeguards lifted, partner-only.
Best OpenAI flagship for agentic coding, research, and computer-use work.
List prices and published scores — the numbers this page's pick is built from.
| Model | Input | Output | Est. month | Context | Speed | Coding | Writing | Research |
|---|---|---|---|---|---|---|---|---|
| Claude Mythos 5Anthropic | $10.00/1M | $50.00/1M | $200 | 1M tokens | Deliberate | 100 | 97 | 99 |
| GPT-5.5OpenAI | $5.00/1M | $30.00/1M | $110 | 1M tokens | Balanced | 96 | 92 | 94 |
Scores out of 100 — how we evaluate models. “Est. month” is 10M in / 2M out at list price: a ceiling, no discounts.
Why each one is on the shortlist for Claude Mythos 5 vs GPT-5.5, what it is genuinely good at, and where we would steer you away from it.
The default answer for Claude Mythos 5 vs GPT-5.5 — 100/100 on the coding axis, and the model we would start with unless the price below rules it out.
Anthropic's most powerful frontier model — the same underlying model as Fable 5 with safeguards lifted in some areas, restricted to vetted enterprise and research partners. The capability ceiling of mid-2026.
You don't have vetted-partner access or don't need lifted safeguards — Fable 5 is the same model, generally available, at the same price.
The most capable model Anthropic has ever shipped — but access is gated to vetted partners because its safeguards are lifted in high-risk areas. For everyone else, Fable 5 is the same model at the same price with standard safety controls. Choose Mythos 5 only if you have partner access and need its security ceiling.
Full pricing, benchmark table and release notes on the Claude Mythos 5 page.
The cost-conscious pick for Claude Mythos 5 vs GPT-5.5, about 42% less per token than Claude Mythos 5 than the top choice while holding 96/100 on coding.
OpenAI's latest agentic flagship for coding, research, computer-use workflows, and long multi-step knowledge work.
You only care about the highest public coding benchmark score or need a cheaper high-volume model.
The strongest OpenAI pick for agentic coding and knowledge work. Claude Opus 4.7 still wins on the public SWE-Bench Pro coding number, but GPT-5.5 is the better OpenAI default when ecosystem, Codex, or computer-use workflows matter.
Full pricing, benchmark table and release notes on the GPT-5.5 page.
UseRightAI recommendations are based on practical decision factors people actually feel in day-to-day use.
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Claude Mythos 5 wins on more of the categories we score — coding, research, long context — so it is the better default of the two. GPT-5.5 is the better pick when your work is mostly agentic coding and computer-use workflows. Neither is universally "better": Claude Mythos 5 is aimed at frontier cybersecurity research and autonomous vulnerability discovery, GPT-5.5 at agentic coding and computer-use workflows.
GPT-5.5 is cheaper at $5/1M input and $30/1M output. Claude Mythos 5 costs $10/1M input and $50/1M output.
Both Claude Mythos 5 and GPT-5.5 have the same 1M context window.
Claude Mythos 5 is better for coding with a score of 100 vs GPT-5.5's 96 (out of 100). GPT-6 Astra is the overall coding leader in this directory at 100/100.
GPT-5.5 is faster with a balanced speed rating (score: 3) vs Claude Mythos 5's deliberate rating (score: 2). Speed matters most for interactive and high-throughput work; for batch jobs the Claude Mythos 5 latency penalty is usually invisible.
Not generally available — limited to vetted partners after Project Glasswing's private preview. Most teams should use Fable 5, which is the same model with standard safeguards. Premium $10/$50 pricing and a deliberate, high-latency profile. Avoid it if you don't have vetted-partner access or don't need lifted safeguards — Fable 5 is the same model, generally available, at the same price. That is the main case for looking at GPT-5.5 instead.
Claude Opus 4.7 leads GPT-5.5 on SWE-Bench Pro for pure coding ceiling. Premium API pricing makes it less attractive for high-volume low-risk work. Avoid it if you only care about the highest public coding benchmark score or need a cheaper high-volume model. Against Claude Mythos 5 specifically, the gap shows up most on coding (100 vs 96).
Take a moderate workload of 10M input and 2M output tokens a month. Claude Mythos 5 runs $200.00 (at $10/1M in and $50/1M out); GPT-5.5 runs $110.00 (at $5/1M in and $30/1M out). That is a $90.00/month difference — GPT-5.5 is the cheaper of the two at this volume, and the gap scales linearly as you send more. Output tokens dominate the bill on both, so prompt length matters far less than response length.
Yes, and for most teams that beats picking one. A common split is Claude Mythos 5 for frontier cybersecurity research and autonomous vulnerability discovery, with GPT-5.5 handling agentic coding and computer-use workflows. Routing high-volume, low-stakes calls to GPT-5.5 at $5/1M and reserving Claude Mythos 5 for the hard cases is usually the cheapest arrangement that does not cost you quality.