GPT-5.1-Codex vs Hermes 4 405B
GPT-5.1-Codex leads Hermes 4 405B on the Artificial Analysis Intelligence Index, 23.7 to 7.5, and Hermes 4 405B costs 3.3x less per output token ($3.00 vs $10.00 per million). Updated October 22, 2026; 1 benchmarks have a result for both.
GPT-5.1-Codex or Hermes 4 405B: which to pick
Only GPT-5.1-Codex has a coding score, 15.3 on the Vibe Coding Index; Hermes 4 405B has none, so the two cannot be ranked on coding.
Pick Hermes 4 405B for output tokens 3.3x cheaper ($3.00 vs $10.00 per million).
- Shared results
- 1
- GPT-5.1-Codex only
- 25
- Hermes 4 405B only
- 1
- Like-for-like categories
- 1 of 9
Only benchmarks that tested both models count toward a pick; a result only one model has is shown but not compared.
Which one for your work
Each card is decided by one number both models carry. Where only one has it, the card says so and makes no call.
Coding
Vibe Coding Index, six public coding benchmarks
No call
Only GPT-5.1-Codex has a coding score, so no call is made.
One side not measured
Intelligence
AA Intelligence Index
GPT-5.1-Codex
GPT-5.1-Codex leads, 23.7 against 7.5.
Same board, both measured
Web design
Design Arena: websites
No call
Only GPT-5.1-Codex has a Design Arena: websites result, 1161.
Directional only
Long documents
Listed context window
GPT-5.1-Codex
GPT-5.1-Codex takes 400K tokens against 131K.
Listed by OpenRouter
Everyday cost
1K input + 500 output tokens
Hermes 4 405B
GPT-5.1-Codex $0.0063, Hermes 4 405B $0.0025 per turn.
List prices
Cost per solved task
One SWE-bench Verified task, solved
No call
Only GPT-5.1-Codex has the number, $0.892.
Directional only
At a glance
- Coding index
- GPT-5.1-Codex 15.3 from 2 benchmarks, Hermes 4 405B not benchmarked.
- Widest category
- Intelligence, 16.2 points apart on average over 1 shared benchmark.
- Widest single gap
- AA Intelligence Index: GPT-5.1-Codex 23.7 against Hermes 4 405B 7.5, 16.2 points apart on a 0 to 100 scale.
- Output price
- GPT-5.1-Codex $10.00 against Hermes 4 405B $3.00 per million output tokens, 3.3x apart.
- Context window
- GPT-5.1-Codex takes 400K tokens, Hermes 4 405B 131K.
Benchmark by benchmark
First the score: boards each model leads, per category, where both have a result. Then every board, a category to a fold; bars are each result on a 0 to 100 scale, so compare the two in a row, not one row with another.
| Category | GPT-5.1-Codex | Bars | Hermes 4 405B | Ties |
|---|---|---|---|---|
| Intelligence | 1 | 0 | ||
| All shared boards | 1 | 0 |
CodingDirectional onlySix of these boards feed the Vibe Coding Index9 boards, none shared
| Benchmark | GPT-5.1-Codex | Hermes 4 405B | Leader |
|---|---|---|---|
| SWE-bench Verified | 66.0% | Not measured | Only GPT-5.1-Codex measured |
| LMArena WebDev | 1337 | Not measured | Only GPT-5.1-Codex measured |
| LiveCodeBench (Vals AI) | 85.5% | Not measured | Only GPT-5.1-Codex measured |
| Vibe Code Bench (Vals AI) | 13.1% | Not measured | Only GPT-5.1-Codex measured |
| LiveCodeBench (Artificial Analysis run) | 84.9% | Not measured | Only GPT-5.1-Codex measured |
| Terminal-Bench Hard (Artificial Analysis run) | 34.8% | Not measured | Only GPT-5.1-Codex measured |
| Terminal-Bench | 57.8% | Not measured | Only GPT-5.1-Codex measured |
| ALE-Bench | 1244.9 | Not measured | Only GPT-5.1-Codex measured |
| LMArena WebDev: HTML | 1346 | Not measured | Only GPT-5.1-Codex measured |
| Neither model has a result on the other 30 boards here | |||
IntelligenceLike-for-likePublic boards, shown as published, kept out of the index10
| Benchmark | GPT-5.1-Codex | Hermes 4 405B | Leader |
|---|---|---|---|
| AA Intelligence Index | 23.7 | 7.5 | GPT-5.1-Codex |
| Neither model has a result on the other 1 board here | |||
Agentic workDirectional onlyPublic boards, shown as published, kept out of the index4 boards, none shared
| Benchmark | GPT-5.1-Codex | Hermes 4 405B | Leader |
|---|---|---|---|
| Design Arena: agents building web apps | 1018 | Not measured | Only GPT-5.1-Codex measured |
| Design Arena: agents building full-stack apps | 1086 | Not measured | Only GPT-5.1-Codex measured |
| Design Arena: agents building mobile apps | 1191 | Not measured | Only GPT-5.1-Codex measured |
| τ²-Bench Telecom | 83.0% | Not measured | Only GPT-5.1-Codex measured |
| Neither model has a result on the other 37 boards here | |||
ReasoningDirectional onlyPublic boards, shown as published, kept out of the index3 boards, none shared
| Benchmark | GPT-5.1-Codex | Hermes 4 405B | Leader |
|---|---|---|---|
| GPQA Diamond (Artificial Analysis run) | 86.0% | Not measured | Only GPT-5.1-Codex measured |
| Humanity's Last Exam (Artificial Analysis run) | 25.7% | Not measured | Only GPT-5.1-Codex measured |
| Kagi LLM Benchmark | Not measured | 55.8% | Only Hermes 4 405B measured |
| Neither model has a result on the other 19 boards here | |||
MathDirectional onlyPublic boards, shown as published, kept out of the index2 boards, none shared
| Benchmark | GPT-5.1-Codex | Hermes 4 405B | Leader |
|---|---|---|---|
| AA Math Index | 95.7 | Not measured | Only GPT-5.1-Codex measured |
| AIME 2025 (Artificial Analysis run) | 95.7% | Not measured | Only GPT-5.1-Codex measured |
| Neither model has a result on the other 11 boards here | |||
KnowledgeDirectional onlyPublic boards, shown as published, kept out of the index1 board, none shared
| Benchmark | GPT-5.1-Codex | Hermes 4 405B | Leader |
|---|---|---|---|
| MMLU Pro (Artificial Analysis run) | 86.0% | Not measured | Only GPT-5.1-Codex measured |
| Neither model has a result on the other 17 boards here | |||
Web designDirectional onlyPublic boards, shown as published, kept out of the index5 boards, none shared
| Benchmark | GPT-5.1-Codex | Hermes 4 405B | Leader |
|---|---|---|---|
| Design Arena: websites | 1161 | Not measured | Only GPT-5.1-Codex measured |
| Design Arena: UI components | 1234 | Not measured | Only GPT-5.1-Codex measured |
| Design Arena: game dev | 1137 | Not measured | Only GPT-5.1-Codex measured |
| Design Arena: data viz | 1213 | Not measured | Only GPT-5.1-Codex measured |
| Design Arena: all code categories | 1152 | Not measured | Only GPT-5.1-Codex measured |
| Neither model has a result on the other 4 boards here | |||
GeneralDirectional onlyPublic boards, shown as published, kept out of the index2 boards, none shared
| Benchmark | GPT-5.1-Codex | Hermes 4 405B | Leader |
|---|---|---|---|
| IFBench | 70.0% | Not measured | Only GPT-5.1-Codex measured |
| Long context reasoning (AA-LCR) | 69.3% | Not measured | Only GPT-5.1-Codex measured |
| Neither model has a result on the other 44 boards here | |||
Image generationNot comparablePublic boards, shown as published, kept out of the index0 boards, none shared
| Benchmark | GPT-5.1-Codex | Hermes 4 405B | Leader |
|---|---|---|---|
| Neither model has a result on 5 boards here | |||
What each workload costs
Three fixed token mixes at each model's listed price, so per-token rates become a bill.
Chat turn
1K input + 500 output tokens
Hermes 4 405B costs less
Repository review
50K input + 3K output tokens
Hermes 4 405B costs less
Agent loop
200K input + 10K output tokens
Hermes 4 405B costs less
Listed OpenRouter rates, without cache or batch discounts. A workload that does not fit a model's context window would need splitting.
Specification differences
The leading value in a row is marked; a row with a missing value names no leader. Our two rows are marked in red.
| Specification | OpenAI GPT-5.1-Codex | Nous Hermes 4 405B |
|---|---|---|
| Maker | OpenAI | Nous Research |
| Weights | No public weights listed | Open weights |
| Released | November 13, 2025 | August 26, 2025 |
| Context window | 400K | 131K |
| Input $/Mtok | $1.25 | $1.00 |
| Output $/Mtok | $10.00 | $3.00 |
| Coding index | 15.3 | Not benchmarked |
| Independent measurements behind it | 2 | 0 |
| Cost per solved task | $0.892 | Not computable |
| Source | OpenRouter listing | OpenRouter listing |
Questions
Is GPT-5.1-Codex better than Hermes 4 405B for coding?
Only GPT-5.1-Codex has a coding score, 15.3 on the Vibe Coding Index; Hermes 4 405B has none, so the two cannot be ranked on coding. Pick Hermes 4 405B for output tokens 3.3x cheaper ($3.00 vs $10.00 per million).
Which is cheaper, GPT-5.1-Codex or Hermes 4 405B?
GPT-5.1-Codex costs $1.25 per million input tokens and $10.00 per million output tokens; Hermes 4 405B costs $1.00 and $3.00. Cost per solved task is known for GPT-5.1-Codex only.
Which has the bigger context window, GPT-5.1-Codex or Hermes 4 405B?
GPT-5.1-Codex, with 400K tokens against 131K.
How many benchmarks is the GPT-5.1-Codex vs Hermes 4 405B comparison based on?
1 benchmarks have a result for both models as of October 22, 2026. GPT-5.1-Codex's coding index rests on 2 independent benchmarks and Hermes 4 405B's on 0. Where only one model has a result, the page says so instead of naming a winner.