Grok 4.20 vs Nemotron 3.5 Lightning
Grok 4.20 leads Nemotron 3.5 Lightning on coding, 33.3 to 22.6 on the Vibe Coding Index, and Nemotron 3.5 Lightning costs 17.0x less per output token ($0.147 vs $2.50 per million). Updated October 22, 2026; 14 benchmarks have a result for both.
Grok 4.20 or Nemotron 3.5 Lightning: which to pick
Pick Grok 4.20 for coding: it scores 33.3 on the Vibe Coding Index against 22.6 for Nemotron 3.5 Lightning.
Pick Nemotron 3.5 Lightning for output tokens 17.0x cheaper ($0.147 vs $2.50 per million) and a lower cost per solved task ($0.06 against $0.72).
- Shared results
- 14
- Grok 4.20 only
- 41
- Nemotron 3.5 Lightning only
- 6
- Like-for-like categories
- 6 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
Grok 4.20
Grok 4.20 scores 33.3 against 22.6.
2 benchmarks behind each score
Intelligence
AA Intelligence Index
Grok 4.20
Grok 4.20 leads, 25.7 against 12.9.
Same board, both measured
Agentic work
AA Agentic Index
No call
Only Nemotron 3.5 Lightning has a AA Agentic Index result, 3.5.
Directional only
Reasoning
GPQA Diamond
No call
Only Grok 4.20 has a GPQA Diamond result, 88.6%.
Directional only
Math
AIME
No call
Only Grok 4.20 has a AIME result, 96.5%.
Directional only
Knowledge
MMLU Pro
No call
Only Grok 4.20 has a MMLU Pro result, 86.3%.
Directional only
Web design
Design Arena: websites
No call
Only Grok 4.20 has a Design Arena: websites result, 1229.
Directional only
Long documents
Listed context window
Grok 4.20
Grok 4.20 takes 2M tokens against 262K.
Listed by OpenRouter
Everyday cost
1K input + 500 output tokens
Nemotron 3.5 Lightning
Grok 4.20 $0.0025, Nemotron 3.5 Lightning $0.0001 per turn.
List prices
Cost per solved task
One SWE-bench Verified task, solved
Nemotron 3.5 Lightning
Grok 4.20 $0.72, Nemotron 3.5 Lightning $0.06.
Published attempt cost and pass rate
At a glance
- Coding index
- Grok 4.20 33.3 from 2 benchmarks, Nemotron 3.5 Lightning 22.6 from 2 benchmarks.
- Widest category
- General, 33.9 points apart on average over 2 shared benchmarks.
- Widest single gap
- MedScribe (Vals AI): Grok 4.20 63.4% against Nemotron 3.5 Lightning 4.3%, 59.1 points apart on a 0 to 100 scale.
- Output price
- Grok 4.20 $2.50 against Nemotron 3.5 Lightning $0.147 per million output tokens, 17.0x apart.
- Context window
- Grok 4.20 takes 2M tokens, Nemotron 3.5 Lightning 262K.
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 | Grok 4.20 | Bars | Nemotron 3.5 Lightning | Ties |
|---|---|---|---|---|
| Coding | 3 | 1 | ||
| Intelligence | 1 | 0 | ||
| Agentic work | 3 | 1 | ||
| Reasoning | 2 | 0 | ||
| Knowledge | 1 | 0 | ||
| General | 2 | 0 | ||
| All shared boards | 12 | 2 |
CodingLike-for-likeSix of these boards feed the Vibe Coding Index31
| Benchmark | Grok 4.20 | Nemotron 3.5 Lightning | Leader |
|---|---|---|---|
| AA Coding Index | Not measured | 26.8 | Only Nemotron 3.5 Lightning measured |
| LiveCodeBench (Vals AI) | 84.3% | Not measured | Only Grok 4.20 measured |
| SWE-bench Verified (Vals AI) | 72.2% | 52.8% | Grok 4.20 |
| Vibe Code Bench (Vals AI) | 4.1% | 0.0% | Grok 4.20 |
| Code migration (Vals AI) | 0.3% | 3.0% | Nemotron 3.5 Lightning |
| ProgramBench (Vals AI) | Not measured | 0.0% | Only Nemotron 3.5 Lightning measured |
| Terminal-Bench 2.1 (Vals AI) | 44.2% | 10.9% | Grok 4.20 |
| CyberBench (Vals AI) | Not measured | 29.5% | Only Nemotron 3.5 Lightning measured |
| SciCode | Not measured | 32.1% | Only Nemotron 3.5 Lightning measured |
| Terminal-Bench Hard (Artificial Analysis run) | 37.9% | Not measured | Only Grok 4.20 measured |
| Terminal-Bench | 57.3% | Not measured | Only Grok 4.20 measured |
| WeirdML | 52.3% | Not measured | Only Grok 4.20 measured |
| ALE-Bench | Not measured | 769.2 | Only Nemotron 3.5 Lightning measured |
| Neither model has a result on the other 26 boards here | |||
IntelligenceLike-for-likePublic boards, shown as published, kept out of the index10
| Benchmark | Grok 4.20 | Nemotron 3.5 Lightning | Leader |
|---|---|---|---|
| AA Intelligence Index | 25.7 | 12.9 | Grok 4.20 |
| Epoch Capabilities Index | 152.1 | Not measured | Only Grok 4.20 measured |
Agentic workLike-for-likePublic boards, shown as published, kept out of the index31
| Benchmark | Grok 4.20 | Nemotron 3.5 Lightning | Leader |
|---|---|---|---|
| AA Agentic Index | Not measured | 3.5 | Only Nemotron 3.5 Lightning measured |
| Design Arena: agents building web apps | 1144 | Not measured | Only Grok 4.20 measured |
| Design Arena: agents building full-stack apps | 1054 | Not measured | Only Grok 4.20 measured |
| Design Arena: agents building mobile apps | 1090 | Not measured | Only Grok 4.20 measured |
| Design Arena: agents building Android apps | 1045 | Not measured | Only Grok 4.20 measured |
| Design Arena: agents building Godot games | 1089 | Not measured | Only Grok 4.20 measured |
| Design Arena: HTML slides | 1180 | Not measured | Only Grok 4.20 measured |
| Finance Agent (Vals AI) | 28.5% | 18.5% | Grok 4.20 |
| Tax Agent Bench (Vals AI) | 7.0% | 2.6% | Grok 4.20 |
| Legal Research Bench (Vals AI) | 13.9% | 2.9% | Grok 4.20 |
| Excel Modeling Benchmark (Vals AI) | 11.7% | 17.0% | Nemotron 3.5 Lightning |
| τ²-Bench Telecom | 93.0% | Not measured | Only Grok 4.20 measured |
| Vending-Bench 2 | $4,663 | Not measured | Only Grok 4.20 measured |
| Neither model has a result on the other 28 boards here | |||
ReasoningLike-for-likePublic boards, shown as published, kept out of the index20
| Benchmark | Grok 4.20 | Nemotron 3.5 Lightning | Leader |
|---|---|---|---|
| GPQA Diamond | 88.6% | Not measured | Only Grok 4.20 measured |
| MMMU Pro (Vals AI) | 83.5% | Not measured | Only Grok 4.20 measured |
| GPQA Diamond (Artificial Analysis run) | 91.1% | 74.3% | Grok 4.20 |
| Humanity's Last Exam (Artificial Analysis run) | 34.5% | 10.6% | Grok 4.20 |
| ARC-AGI | 89.5% | Not measured | Only Grok 4.20 measured |
| ARC-AGI-2 | 65.1% | Not measured | Only Grok 4.20 measured |
| Kagi LLM Benchmark | 75.0% | Not measured | Only Grok 4.20 measured |
| Neither model has a result on the other 15 boards here | |||
MathDirectional onlyPublic boards, shown as published, kept out of the index1 board, none shared
| Benchmark | Grok 4.20 | Nemotron 3.5 Lightning | Leader |
|---|---|---|---|
| AIME | 96.5% | Not measured | Only Grok 4.20 measured |
| Neither model has a result on the other 12 boards here | |||
KnowledgeLike-for-likePublic boards, shown as published, kept out of the index10
| Benchmark | Grok 4.20 | Nemotron 3.5 Lightning | Leader |
|---|---|---|---|
| MMLU Pro | 86.3% | Not measured | Only Grok 4.20 measured |
| LegalBench (Vals AI) | 77.7% | Not measured | Only Grok 4.20 measured |
| CaseLaw (Vals AI) | 54.4% | Not measured | Only Grok 4.20 measured |
| CorpFin (Vals AI) | 63.7% | 54.2% | Grok 4.20 |
| TaxEval (Vals AI) | 74.1% | Not measured | Only Grok 4.20 measured |
| MortgageTax (Vals AI) | 45.4% | Not measured | Only Grok 4.20 measured |
| MedQA (Vals AI) | 94.5% | Not measured | Only Grok 4.20 measured |
| MedCode (Vals AI) | 32.2% | Not measured | Only Grok 4.20 measured |
| Neither model has a result on the other 10 boards here | |||
Web designDirectional onlyPublic boards, shown as published, kept out of the index8 boards, none shared
| Benchmark | Grok 4.20 | Nemotron 3.5 Lightning | Leader |
|---|---|---|---|
| Design Arena: websites | 1229 | Not measured | Only Grok 4.20 measured |
| Design Arena: UI components | 1200 | Not measured | Only Grok 4.20 measured |
| Design Arena: game dev | 1193 | Not measured | Only Grok 4.20 measured |
| Design Arena: data viz | 1217 | Not measured | Only Grok 4.20 measured |
| Design Arena: 3D | 1193 | Not measured | Only Grok 4.20 measured |
| Design Arena: all code categories | 1221 | Not measured | Only Grok 4.20 measured |
| Design Arena: SVG | 1165 | Not measured | Only Grok 4.20 measured |
| Design Arena: ASCII art | 1175 | Not measured | Only Grok 4.20 measured |
| Neither model has a result on the other 1 board here | |||
GeneralLike-for-likePublic boards, shown as published, kept out of the index20
| Benchmark | Grok 4.20 | Nemotron 3.5 Lightning | Leader |
|---|---|---|---|
| SAGE (Vals AI) | 38.2% | Not measured | Only Grok 4.20 measured |
| MedScribe (Vals AI) | 63.4% | 4.3% | Grok 4.20 |
| Vals Multimodal Index | 39.1% | Not measured | Only Grok 4.20 measured |
| IFBench | 81.2% | Not measured | Only Grok 4.20 measured |
| Long context reasoning (AA-LCR) | 69.0% | 60.3% | Grok 4.20 |
| DTBench | 90.1% | Not measured | Only Grok 4.20 measured |
| LMCA | 38.7% | Not measured | Only Grok 4.20 measured |
| CL-bench | 22.2% | Not measured | Only Grok 4.20 measured |
| CL-bench Life | 11.9% | Not measured | Only Grok 4.20 measured |
| Neither model has a result on the other 37 boards here | |||
Image generationNot comparablePublic boards, shown as published, kept out of the index0 boards, none shared
| Benchmark | Grok 4.20 | Nemotron 3.5 Lightning | 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
Nemotron 3.5 Lightning costs less
Repository review
50K input + 3K output tokens
Nemotron 3.5 Lightning costs less
Agent loop
200K input + 10K output tokens
Nemotron 3.5 Lightning 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 | SpaceXAI Grok 4.20 | NVIDIA Nemotron 3.5 Lightning |
|---|---|---|
| Maker | xAI | NVIDIA |
| Weights | No public weights listed | Open weights |
| Released | March 31, 2026 | August 11, 2026 |
| Context window | 2M | 262K |
| Input $/Mtok | $1.25 | $0.0534 |
| Output $/Mtok | $2.50 | $0.147 |
| Coding index | 33.3 | 22.6 |
| Independent measurements behind it | 2 | 2 |
| Cost per solved task | $0.72 | $0.06 |
| Source | OpenRouter listing | OpenRouter listing |
Questions
Is Grok 4.20 better than Nemotron 3.5 Lightning for coding?
Pick Grok 4.20 for coding: it scores 33.3 on the Vibe Coding Index against 22.6 for Nemotron 3.5 Lightning. Pick Nemotron 3.5 Lightning for output tokens 17.0x cheaper ($0.147 vs $2.50 per million) and a lower cost per solved task ($0.06 against $0.72).
Which is cheaper, Grok 4.20 or Nemotron 3.5 Lightning?
Grok 4.20 costs $1.25 per million input tokens and $2.50 per million output tokens; Nemotron 3.5 Lightning costs $0.0534 and $0.147. Per solved SWE-bench Verified task, Grok 4.20 costs $0.72 and Nemotron 3.5 Lightning $0.06.
Which has the bigger context window, Grok 4.20 or Nemotron 3.5 Lightning?
Grok 4.20, with 2M tokens against 262K.
How many benchmarks is the Grok 4.20 vs Nemotron 3.5 Lightning comparison based on?
14 benchmarks have a result for both models as of October 22, 2026. Grok 4.20's coding index rests on 2 independent benchmarks and Nemotron 3.5 Lightning's on 2. Where only one model has a result, the page says so instead of naming a winner.