GPT-5 Mini vs Grok 4.20
GPT-5 Mini leads Grok 4.20 on coding, 34.2 to 33.3 on the Vibe Coding Index, and GPT-5 Mini costs 1.3x less per output token ($2.00 vs $2.50 per million). Updated October 21, 2026; 39 benchmarks have a result for both.
GPT-5 Mini or Grok 4.20: which to pick
GPT-5 Mini and Grok 4.20 are level for coding, 34.2 against 33.3 on the Vibe Coding Index, so price and context decide.
Pick Grok 4.20 for a larger context window (2M against 400K tokens) and work measured by SWE-bench Verified (Vals AI) or Terminal-Bench Hard (Artificial Analysis run), where it leads. Pick GPT-5 Mini for output tokens 1.3x cheaper ($2.00 vs $2.50 per million) and a lower cost per solved task ($0.08 against $0.72).
- Shared results
- 39
- GPT-5 Mini only
- 59
- Grok 4.20 only
- 15
- Like-for-like categories
- 8 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
Level: 34.2 against 33.3, inside 2 points.
2 benchmarks behind each score
Intelligence
AA Intelligence Index
Grok 4.20
Grok 4.20 leads, 25.7 against 20.6.
Same board, both measured
Reasoning
GPQA Diamond
Grok 4.20
Grok 4.20 leads, 88.6% against 80.3%.
Same board, both measured
Math
AIME
Grok 4.20
Grok 4.20 leads, 96.5% against 91.5%.
Same board, both measured
Knowledge
MMLU Pro
Grok 4.20
Grok 4.20 leads, 86.3% against 82.2%.
Same board, both measured
Web design
Design Arena: websites
Grok 4.20
Grok 4.20 leads, 1229 against 1125.
Same board, both measured
Long documents
Listed context window
Grok 4.20
Grok 4.20 takes 2M tokens against 400K.
Listed by OpenRouter
Everyday cost
1K input + 500 output tokens
GPT-5 Mini
GPT-5 Mini $0.0013, Grok 4.20 $0.0025 per turn.
List prices
Cost per solved task
One SWE-bench Verified task, solved
GPT-5 Mini
GPT-5 Mini $0.08, Grok 4.20 $0.72.
Published attempt cost and pass rate
At a glance
- Coding index
- GPT-5 Mini 34.2 from 2 benchmarks, Grok 4.20 33.3 from 2 benchmarks.
- Widest category
- Agentic work, 25.5 points apart on average over 2 shared benchmarks.
- Widest single gap
- ARC-AGI-2: GPT-5 Mini 4.4% against Grok 4.20 65.1%, 60.7 points apart on a 0 to 100 scale.
- Output price
- GPT-5 Mini $2.00 against Grok 4.20 $2.50 per million output tokens, 1.3x apart.
- Context window
- GPT-5 Mini takes 400K tokens, Grok 4.20 2M.
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 Mini | Bars | Grok 4.20 | Ties |
|---|---|---|---|---|
| Coding | 3 | 3 | ||
| Intelligence | 0 | 2 | ||
| Agentic work | 0 | 2 | ||
| Reasoning | 0 | 6 | ||
| Math | 0 | 1 | ||
| Knowledge | 6 | 2 | ||
| Web design | 0 | 8 | ||
| General | 3 | 3 | ||
| All shared boards | 12 | 27 |
CodingLike-for-likeSix of these boards feed the Vibe Coding Index33
| Benchmark | GPT-5 Mini | Grok 4.20 | Leader |
|---|---|---|---|
| SWE-bench Verified | 59.8% | Not measured | Only GPT-5 Mini measured |
| SWE-bench Multilingual | 39.7% | Not measured | Only GPT-5 Mini measured |
| LiveCodeBench (Vals AI) | 86.6% | 84.3% | GPT-5 Mini |
| SWE-bench Verified (Vals AI) | 60.8% | 72.2% | Grok 4.20 |
| Vibe Code Bench (Vals AI) | 14.2% | 4.1% | GPT-5 Mini |
| Code migration (Vals AI) | Not measured | 0.3% | Only Grok 4.20 measured |
| Terminal-Bench 2.1 (Vals AI) | Not measured | 44.2% | Only Grok 4.20 measured |
| LiveCodeBench (Artificial Analysis run) | 83.8% | Not measured | Only GPT-5 Mini measured |
| SciCode | 39.0% | Not measured | Only GPT-5 Mini measured |
| Terminal-Bench Hard (Artificial Analysis run) | 33.3% | 37.9% | Grok 4.20 |
| Terminal-Bench | 34.8% | 57.3% | Grok 4.20 |
| WeirdML | 52.7% | 52.3% | GPT-5 Mini |
| LMArena Text: coding | 1406 | Not measured | Only GPT-5 Mini measured |
| LMArena Text: software and IT | 1394 | Not measured | Only GPT-5 Mini measured |
| Neither model has a result on the other 24 boards here | |||
IntelligenceLike-for-likePublic boards, shown as published, kept out of the index02
| Benchmark | GPT-5 Mini | Grok 4.20 | Leader |
|---|---|---|---|
| AA Intelligence Index | 20.6 | 25.7 | Grok 4.20 |
| Epoch Capabilities Index | 145.3 | 152.1 | Grok 4.20 |
Agentic workLike-for-likePublic boards, shown as published, kept out of the index02
| Benchmark | GPT-5 Mini | Grok 4.20 | Leader |
|---|---|---|---|
| Design Arena: agents building web apps | Not measured | 1144 | Only Grok 4.20 measured |
| Design Arena: agents building full-stack apps | Not measured | 1054 | Only Grok 4.20 measured |
| Design Arena: agents building mobile apps | Not measured | 1090 | Only Grok 4.20 measured |
| Design Arena: agents building Android apps | Not measured | 1052 | Only Grok 4.20 measured |
| Design Arena: agents building Godot games | Not measured | 1089 | Only Grok 4.20 measured |
| Design Arena: HTML slides | Not measured | 1180 | Only Grok 4.20 measured |
| Finance Agent (Vals AI) | Not measured | 28.5% | Only Grok 4.20 measured |
| Tax Agent Bench (Vals AI) | Not measured | 7.0% | Only Grok 4.20 measured |
| Legal Research Bench (Vals AI) | Not measured | 13.9% | Only Grok 4.20 measured |
| Excel Modeling Benchmark (Vals AI) | Not measured | 11.7% | Only Grok 4.20 measured |
| τ²-Bench Telecom | 71.1% | 93.0% | Grok 4.20 |
| Vending-Bench 2 | -$31 | $4,663 | Grok 4.20 |
| Neither model has a result on the other 27 boards here | |||
ReasoningLike-for-likePublic boards, shown as published, kept out of the index06
| Benchmark | GPT-5 Mini | Grok 4.20 | Leader |
|---|---|---|---|
| GPQA Diamond | 80.3% | 88.6% | Grok 4.20 |
| MMMU Pro (Vals AI) | 78.9% | 83.5% | Grok 4.20 |
| GPQA Diamond (Artificial Analysis run) | 82.8% | 91.1% | Grok 4.20 |
| Humanity's Last Exam (Artificial Analysis run) | 21.5% | 34.5% | Grok 4.20 |
| GPQA Diamond (Epoch AI run) | 75.0% | Not measured | Only GPT-5 Mini measured |
| ARC-AGI | 54.3% | 89.5% | Grok 4.20 |
| ARC-AGI-2 | 4.4% | 65.1% | Grok 4.20 |
| Chess puzzles | 24.0% | Not measured | Only GPT-5 Mini measured |
| Mystery game puzzles | 10.0% | Not measured | Only GPT-5 Mini measured |
| VPCT | 40.2% | Not measured | Only GPT-5 Mini measured |
| LMArena Text: hard prompts | 1380 | Not measured | Only GPT-5 Mini measured |
| LMArena Text: expert | 1379 | Not measured | Only GPT-5 Mini measured |
| LMArena Text: hard prompts in English | 1383 | Not measured | Only GPT-5 Mini measured |
| LMArena Vision: diagrams | 1202 | Not measured | Only GPT-5 Mini measured |
| LMArena Vision: homework | 1210 | Not measured | Only GPT-5 Mini measured |
| Neither model has a result on the other 6 boards here | |||
MathLike-for-likePublic boards, shown as published, kept out of the index01
| Benchmark | GPT-5 Mini | Grok 4.20 | Leader |
|---|---|---|---|
| AIME | 91.5% | 96.5% | Grok 4.20 |
| MATH 500 (Vals AI) | 94.8% | Not measured | Only GPT-5 Mini measured |
| MGSM (Vals AI) | 92.6% | Not measured | Only GPT-5 Mini measured |
| AA Math Index | 90.7 | Not measured | Only GPT-5 Mini measured |
| AIME 2025 (Artificial Analysis run) | 90.7% | Not measured | Only GPT-5 Mini measured |
| OTIS Mock AIME | 86.7% | Not measured | Only GPT-5 Mini measured |
| FrontierMath, tiers 1 to 3 | 46.7% | Not measured | Only GPT-5 Mini measured |
| FrontierMath, tier 4 | 12.2% | Not measured | Only GPT-5 Mini measured |
| ProofBench | 9.0% | Not measured | Only GPT-5 Mini measured |
| MATH level 5 | 97.8% | Not measured | Only GPT-5 Mini measured |
| LMArena Text: math | 1378 | Not measured | Only GPT-5 Mini measured |
| LMArena Text: mathematical work | 1380 | Not measured | Only GPT-5 Mini measured |
| Neither model has a result on the other 1 board here | |||
KnowledgeLike-for-likePublic boards, shown as published, kept out of the index62
| Benchmark | GPT-5 Mini | Grok 4.20 | Leader |
|---|---|---|---|
| MMLU Pro | 82.2% | 86.3% | Grok 4.20 |
| LegalBench (Vals AI) | 81.8% | 77.7% | GPT-5 Mini |
| CaseLaw (Vals AI) | 68.5% | 54.4% | GPT-5 Mini |
| CorpFin (Vals AI) | 60.2% | 63.7% | Grok 4.20 |
| TaxEval (Vals AI) | 75.2% | 74.1% | GPT-5 Mini |
| MortgageTax (Vals AI) | 66.9% | 45.4% | GPT-5 Mini |
| MedQA (Vals AI) | 96.1% | 94.5% | GPT-5 Mini |
| MedCode (Vals AI) | 43.0% | 32.2% | GPT-5 Mini |
| MMLU Pro (Artificial Analysis run) | 83.7% | Not measured | Only GPT-5 Mini measured |
| SimpleQA Verified | 21.6% | Not measured | Only GPT-5 Mini measured |
| LMArena Text: science | 1371 | Not measured | Only GPT-5 Mini measured |
| LMArena Text: medicine and healthcare | 1380 | Not measured | Only GPT-5 Mini measured |
| LMArena Text: legal and government | 1375 | Not measured | Only GPT-5 Mini measured |
| LMArena Text: business and finance | 1358 | Not measured | Only GPT-5 Mini measured |
| Neither model has a result on the other 3 boards here | |||
Web designLike-for-likePublic boards, shown as published, kept out of the index08
| Benchmark | GPT-5 Mini | Grok 4.20 | Leader |
|---|---|---|---|
| Design Arena: websites | 1125 | 1229 | Grok 4.20 |
| Design Arena: UI components | 1106 | 1199 | Grok 4.20 |
| Design Arena: game dev | 1130 | 1192 | Grok 4.20 |
| Design Arena: data viz | 1130 | 1217 | Grok 4.20 |
| Design Arena: 3D | 1037 | 1193 | Grok 4.20 |
| Design Arena: all code categories | 1115 | 1221 | Grok 4.20 |
| Design Arena: SVG | 1091 | 1164 | Grok 4.20 |
| Design Arena: ASCII art | 1125 | 1174 | Grok 4.20 |
| Neither model has a result on the other 1 board here | |||
GeneralLike-for-likePublic boards, shown as published, kept out of the index33
| Benchmark | GPT-5 Mini | Grok 4.20 | Leader |
|---|---|---|---|
| SAGE (Vals AI) | 43.0% | 38.2% | GPT-5 Mini |
| MedScribe (Vals AI) | 80.6% | 63.4% | GPT-5 Mini |
| Vals Multimodal Index | Not measured | 39.1% | Only Grok 4.20 measured |
| IFBench | 75.4% | 81.2% | Grok 4.20 |
| Long context reasoning (AA-LCR) | 72.3% | 69.0% | GPT-5 Mini |
| DTBench | 80.5% | 90.1% | Grok 4.20 |
| LMCA | 34.2% | 38.7% | Grok 4.20 |
| Fiction.LiveBench | 69.4% | Not measured | Only GPT-5 Mini measured |
| Creative writing (Lech Mazur) | 83.1% | Not measured | Only GPT-5 Mini measured |
| CL-bench | Not measured | 22.2% | Only Grok 4.20 measured |
| CL-bench Life | Not measured | 11.9% | Only Grok 4.20 measured |
| LMArena Text | 1373 | Not measured | Only GPT-5 Mini measured |
| LMArena Text: instruction following | 1357 | Not measured | Only GPT-5 Mini measured |
| LMArena Text: creative writing | 1325 | Not measured | Only GPT-5 Mini measured |
| LMArena Vision | 1202 | Not measured | Only GPT-5 Mini measured |
| LMArena Text: English | 1379 | Not measured | Only GPT-5 Mini measured |
| LMArena Text: non-English | 1363 | Not measured | Only GPT-5 Mini measured |
| LMArena Text: Chinese | 1386 | Not measured | Only GPT-5 Mini measured |
| LMArena Text: German | 1366 | Not measured | Only GPT-5 Mini measured |
| LMArena Text: Japanese | 1341 | Not measured | Only GPT-5 Mini measured |
| LMArena Text: Korean | 1308 | Not measured | Only GPT-5 Mini measured |
| LMArena Text: French | 1386 | Not measured | Only GPT-5 Mini measured |
| LMArena Text: Spanish | 1354 | Not measured | Only GPT-5 Mini measured |
| LMArena Text: Russian | 1362 | Not measured | Only GPT-5 Mini measured |
| LMArena Text: Polish | 1378 | Not measured | Only GPT-5 Mini measured |
| LMArena Text: multi-turn | 1363 | Not measured | Only GPT-5 Mini measured |
| LMArena Text: longer queries | 1355 | Not measured | Only GPT-5 Mini measured |
| LMArena Text: writing and language | 1344 | Not measured | Only GPT-5 Mini measured |
| LMArena Text: entertainment and media | 1340 | Not measured | Only GPT-5 Mini measured |
| LMArena Vision: English | 1216 | Not measured | Only GPT-5 Mini measured |
| LMArena Vision: Chinese | 1214 | Not measured | Only GPT-5 Mini measured |
| LMArena Vision: reading text | 1199 | Not measured | Only GPT-5 Mini measured |
| LMArena Vision: humor | 1205 | Not measured | Only GPT-5 Mini measured |
| LMArena Vision: captioning | 1217 | Not measured | Only GPT-5 Mini measured |
| LMArena Vision: recognizing things | 1226 | Not measured | Only GPT-5 Mini measured |
| LMArena Vision: creative writing | 1181 | Not measured | Only GPT-5 Mini measured |
| Neither model has a result on the other 10 boards here | |||
Image generationNot comparablePublic boards, shown as published, kept out of the index0 boards, none shared
| Benchmark | GPT-5 Mini | Grok 4.20 | 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
GPT-5 Mini costs less
Repository review
50K input + 3K output tokens
GPT-5 Mini costs less
Agent loop
200K input + 10K output tokens
GPT-5 Mini 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 Mini | SpaceXAI Grok 4.20 |
|---|---|---|
| Maker | OpenAI | xAI |
| Weights | No public weights listed | No public weights listed |
| Released | August 7, 2025 | March 31, 2026 |
| Context window | 400K | 2M |
| Input $/Mtok | $0.25 | $1.25 |
| Output $/Mtok | $2.00 | $2.50 |
| Coding index | 34.2 | 33.3 |
| Independent measurements behind it | 2 | 2 |
| Cost per solved task | $0.08 | $0.72 |
| Source | OpenRouter listing | OpenRouter listing |
Questions
Is GPT-5 Mini better than Grok 4.20 for coding?
GPT-5 Mini and Grok 4.20 are level for coding, 34.2 against 33.3 on the Vibe Coding Index, so price and context decide. Pick Grok 4.20 for a larger context window (2M against 400K tokens) and work measured by SWE-bench Verified (Vals AI) or Terminal-Bench Hard (Artificial Analysis run), where it leads. Pick GPT-5 Mini for output tokens 1.3x cheaper ($2.00 vs $2.50 per million) and a lower cost per solved task ($0.08 against $0.72).
Which is cheaper, GPT-5 Mini or Grok 4.20?
GPT-5 Mini costs $0.25 per million input tokens and $2.00 per million output tokens; Grok 4.20 costs $1.25 and $2.50. Per solved SWE-bench Verified task, GPT-5 Mini costs $0.08 and Grok 4.20 $0.72.
Which has the bigger context window, GPT-5 Mini or Grok 4.20?
Grok 4.20, with 2M tokens against 400K.
How many benchmarks is the GPT-5 Mini vs Grok 4.20 comparison based on?
39 benchmarks have a result for both models as of October 21, 2026. GPT-5 Mini's coding index rests on 2 independent benchmarks and Grok 4.20's on 2. Where only one model has a result, the page says so instead of naming a winner.