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BenchLM
Anthropic logo
Model A
Claude Mythos 5

Anthropic

—

Evidence status unavailable

90% interval unavailable

Claude Mythos 5 vs GPT-5.4 mini

Updated September 4, 2026. Public scores include evidence status and uncertainty. They are not guarantees for a specific workload.

OpenAI logo
Model B
GPT-5.4 mini

OpenAI

62.63/100

Supported · Public rank #59

90% interval 54.6–70.7

Decision reading

At least one model is not scored in the current public ranking lane, so the page does not name an overall quality winner.

5 results are shared. Category rows resting on Estimated evidence or different benchmark sets are marked directional and do not name a winner.

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Which one for your work

Recommendations appear only when a shared evidence basis or an explicit operating constraint supports the call. Secondary and unsupported use cases stay disclosed below the initial list.

  • Long documents

    Prompts that approach the documented context limit

    Claude Mythos 5

    Claude Mythos 5 has the larger documented context window.

    Confidence: documented

  • Chat turn cost

    1K fresh input + 500 output tokens

    GPT-5.4 mini

    GPT-5.4 mini has the lower estimated token cost for this stated workload. Costs use the listed standard API rates.

    Confidence: listed-rates

  • Cache-heavy agent loop cost

    200K cached + 20K fresh input + 10K output tokens

    GPT-5.4 mini

    GPT-5.4 mini has the lower estimated token cost for this stated workload. Costs use the listed standard API rates.

    Confidence: listed-rates

Show secondary and unsupported calls

  • Repository review cost

    50K fresh input + 3K output tokens

    GPT-5.4 mini

    GPT-5.4 mini has the lower estimated token cost for this stated workload. Costs use the listed standard API rates.

    Confidence: listed-rates

  • Coding work

    Code generation, repair, and software-engineering tasks

    Not enough matched evidence

    Claude Mythos 5 is not ranked on the public lane for coding, so no winner is named for coding.

    Confidence: limited

  • Agentic work

    Tool use, computer use, and multi-step task completion

    Not enough matched evidence

    Claude Mythos 5 is not ranked on the public lane for agentic, so no winner is named for agentic.

    Confidence: limited

What is actually comparable

Shared results can support a head-to-head reading. Results present for only one model describe coverage, not superiority.

Shared results
5
Claude Mythos 5 only
10
GPT-5.4 mini only
14
Like-for-like categories
0 / 8

Category results, on a stated basis

Each row shows the public-lane category score for both models: the BenchAlign lane for agentic, coding, and knowledge, and the weighted public rows elsewhere, with the same rank each model page reports. A row is like-for-like only when both scores rest on Supported evidence or the same weighted set. Directional and not-comparable rows remain visible, but they never receive a winner.

Agentic

Not comparable
Claude Mythos 5
Not ranked
GPT-5.4 mini
42.4
Estimated · #113/151
Basis
BenchAlign lane · 4 vs 6 public rows
Reading
Not comparable

Coding

Not comparable
Claude Mythos 5
Not ranked
GPT-5.4 mini
42.9
Supported · #125/183
Basis
BenchAlign lane · 3 vs 4 public rows
Reading
Not comparable

Reasoning

Not comparable
Claude Mythos 5
Not ranked
GPT-5.4 mini
73.5
Unranked · 2 rankable rows
Basis
Provisional lane · 0 vs 0 weighted rows
Reading
Not comparable

Knowledge

Not comparable
Claude Mythos 5
Not ranked
GPT-5.4 mini
56.3
Supported · #53/181
Basis
BenchAlign lane · 3 vs 5 public rows
Reading
Not comparable

Math

Not comparable
Claude Mythos 5
Not ranked
GPT-5.4 mini
44.5
Unranked · 2 rankable rows
Basis
Provisional lane · 1 vs 2 weighted rows
Reading
Not comparable

Multilingual

Not comparable
Claude Mythos 5
Not ranked
GPT-5.4 mini
Not ranked
Basis
Provisional lane · 0 vs 0 weighted rows
Reading
Not comparable

Multimodal

Not comparable
Claude Mythos 5
85.1
Unranked · 3 rankable rows
GPT-5.4 mini
57.2
#31/48
Basis
Provisional lane · 1 vs 1 weighted rows
Reading
Not comparable

Instruction following

Not comparable
Claude Mythos 5
Not ranked
GPT-5.4 mini
89.6
#23/120
Basis
Provisional lane · 0 vs 0 weighted rows
Reading
Not comparable

Ranks count the models scored in each category’s lane, so the agentic, coding, and knowledge denominators (BenchAlign) differ from the provisional-lane categories. Unranked scores sit on the lane’s scale but never name a winner. Like-for-like rows within 0.5 points read as a practical tie.

Shape of the matched evidence

Only shared public evidence is shown. Sparse evidence stays a ruled list rather than being closed into a radar shape.

Too few matched category axes support a radar. The ruled list below shows only shared benchmark results; positions use each benchmark’s normalized display scale when available.

What each workload costs

Three fixed token mixes turn per-token rates into comparable decisions. Each scenario states context fit and whether cached input had to fall back to the published list-input rate.

Chat turn

1K fresh input + 500 output tokens

Claude Mythos 5
$0.035
Fits in one request
GPT-5.4 mini
$0.003
Fits in one request

GPT-5.4 mini has the lower modeled cost

Costs use the listed standard API rates.

Repository review

50K fresh input + 3K output tokens

Claude Mythos 5
$0.65
Fits in one request
GPT-5.4 mini
$0.051
Fits in one request

GPT-5.4 mini has the lower modeled cost

Costs use the listed standard API rates.

Cache-heavy agent loop

200K cached + 20K fresh input + 10K output tokens

Claude Mythos 5
$0.9
Fits in one request
GPT-5.4 mini
$0.075
Fits in one request

GPT-5.4 mini has the lower modeled cost

Costs use the listed standard API rates.

Specification differences

Sourced differences are shown directly. Missing facts stay explicit instead of being inferred from a model name or family.

Cached-input rate

A missing cached-input rate falls back to the listed input rate only in the stated workload estimate.

Claude Mythos 5

$1 per 1M cached input tokens

Claude API pricing

GPT-5.4 mini

$0.075 per 1M cached input tokens

OpenAI pricing

Reasoning profile

Claude Mythos 5

Reasoning

GPT-5.4 mini

Reasoning

Weight access

Claude Mythos 5

Proprietary

GPT-5.4 mini

Proprietary

License

Claude Mythos 5

Proprietary

GPT-5.4 mini

Proprietary

Release date

Claude Mythos 5

2026-06-09

GPT-5.4 mini

2026-03-17

If you already use one of these models
Deployment change
The models list different providers, so authentication, endpoint behavior, limits, and feature support may change.
Quality signal
At least one model is not scored in the current public ranking lane, so the page does not name an overall quality winner.
Workload cost
Repository review: $0.65 vs $0.051. Cache-heavy agent loop: $0.9 vs $0.075.
Context tradeoff
Claude Mythos 5 has the larger documented window (1M).

Run the same representative tasks against both endpoints before changing production traffic.

Benchmark evidence

The full public result ledger is available for audit without forcing a wide desktop table onto a phone.

Browse raw public benchmark evidence29 rows

Agentic

  • Terminal-Bench 2.0

    Claude Mythos 588%
    Source
    GPT-5.4 mini60%
    Source

    Claude Mythos 5 leads this result

  • OSWorld-Verified

    Claude Mythos 585%
    Source
    GPT-5.4 mini72.1%
    Source

    Claude Mythos 5 leads this result

  • BrowseComp

    Claude Mythos 588%
    Source
    GPT-5.4 mini—

    Not directly comparable

  • CyberGym

    Claude Mythos 583.8%
    Source
    GPT-5.4 mini—

    Not directly comparable

  • MCP Atlas

    Claude Mythos 5—
    GPT-5.4 mini57.7%
    Source

    Not directly comparable

  • Toolathlon

    Claude Mythos 5—
    GPT-5.4 mini42.9%
    Source

    Not directly comparable

  • τ²-bench results

    Claude Mythos 5—
    GPT-5.4 mini93.4%
    Source

    Not directly comparable

  • Terminal-Bench 2.1 (Vals)

    Claude Mythos 5—
    GPT-5.4 mini54.7%
    Source

    Not directly comparable

Coding

  • SWE-bench Verified

    Claude Mythos 595.5%
    Source
    GPT-5.4 mini—

    Not directly comparable

  • SWE-bench Pro

    Claude Mythos 580.3%
    Source
    GPT-5.4 mini—

    Not directly comparable

  • Terminal-Bench 2.0

    Claude Mythos 588.0%
    Source
    GPT-5.4 mini—

    Not directly comparable

  • Vibe Code Bench

    Claude Mythos 5—
    GPT-5.4 mini47.97%
    Source

    Not directly comparable

  • FrontierCode 1.1 Main

    Claude Mythos 5—
    GPT-5.4 mini27.0%
    Source

    Not directly comparable

  • LiveCodeBench (Vals)

    Claude Mythos 5—
    GPT-5.4 mini81.5%
    Source

    Not directly comparable

  • SWE-bench (Vals)

    Claude Mythos 5—
    GPT-5.4 mini73.0%
    Source

    Not directly comparable

Knowledge

  • GPQA

    Claude Mythos 594.1%
    Source
    GPT-5.4 mini88%
    Source

    Claude Mythos 5 leads this result

  • HLE

    Claude Mythos 564.5%
    Source
    GPT-5.4 mini41.5%
    Source

    Claude Mythos 5 leads this result

  • HLE w/o tools

    Claude Mythos 559%
    Source
    GPT-5.4 mini28.2%
    Source

    Claude Mythos 5 leads this result

  • GPQA Diamond (Vals)

    Claude Mythos 5—
    GPT-5.4 mini83.1%
    Source

    Not directly comparable

  • MMLU-Pro (Vals)

    Claude Mythos 5—
    GPT-5.4 mini84.6%
    Source

    Not directly comparable

Math

  • USAMO 2026

    Claude Mythos 597.6%
    Source
    GPT-5.4 mini—

    Not directly comparable

  • FrontierMath v2 (Tiers 1-3)

    Claude Mythos 5—
    GPT-5.4 mini28.280%
    Source

    Not directly comparable

  • FrontierMath v2 (Tier 4)

    Claude Mythos 5—
    GPT-5.4 mini2.080%
    Source

    Not directly comparable

Multilingual

  • SWE Multilingual

    Claude Mythos 592.2%
    Source
    GPT-5.4 mini—

    Not directly comparable

Multimodal

  • SWE-bench Multimodal

    Claude Mythos 554.9%
    Source
    GPT-5.4 mini—

    Not directly comparable

  • CharXiv

    Claude Mythos 593.5%
    Source
    GPT-5.4 mini—

    Not directly comparable

  • CharXiv w/o tools

    Claude Mythos 588.9%
    Source
    GPT-5.4 mini—

    Not directly comparable

  • MMMU-Pro

    Claude Mythos 5—
    GPT-5.4 mini76.6%
    Source

    Not directly comparable

  • MMMU-Pro w/ Python

    Claude Mythos 5—
    GPT-5.4 mini78%
    Source

    Not directly comparable

Frequently asked questions

Which is better, Claude Mythos 5 or GPT-5.4 mini?

At least one model is not scored in the current public ranking lane, so the page does not name an overall quality winner. The page therefore keeps the decision tied to the specific documented workload.

Which is better for coding, Claude Mythos 5 or GPT-5.4 mini?

Claude Mythos 5 is not ranked on the public lane for coding, so no winner is named for coding.

Which is better for agentic tasks, Claude Mythos 5 or GPT-5.4 mini?

Claude Mythos 5 is not ranked on the public lane for agentic tasks, so no winner is named for agentic tasks.

Which costs less, Claude Mythos 5 or GPT-5.4 mini?

For the stated presets, chat costs $0.035 on Claude Mythos 5 and $0.003 on GPT-5.4 mini; repository review costs $0.65 and $0.051; the cache-heavy agent loop costs $0.9 and $0.075. Costs use the listed standard API rates.

Which has the larger context window, Claude Mythos 5 or GPT-5.4 mini?

Claude Mythos 5 has the larger documented context window: 1M, compared with 400K.

Related comparisons

Compare API pricing Read the methodology Open the model selector

Last updated September 4, 2026

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