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Grok 4.5 vs o3

Updated October 21, 2026. 69 benchmarks have a result for both. Coding is ranked on the Vibe Coding Index; every other board is shown as published.

Replace Grok 4.5 Replace o3
Grok 4.5xAI
Coding
75.5
Overall
38.8
Output $/M
$6.00
59
o3OpenAI
Coding
70.7
Overall
20.2
Output $/M
$8.00
10
vs boards won of 69 shared

Decision reading

Pick Grok 4.5 for coding: it scores 75.5 on the Vibe Coding Index against 70.7 for o3.

Pick o3 when a solved task costs $0.571 against $0.62, or when what matters is WeirdML or MMMU Pro (Vals AI), where it leads.

Model AGrok 4.5xAI75.5/1002 independent benchmarks$0.62 per solved taskModel Bo3OpenAI70.7/1002 independent benchmarks$0.571 per solved task
Shared results
69
Grok 4.5 only
51
o3 only
28
Like-for-like categories
7 of 9

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

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.

At a glance

Coding index
Grok 4.5 75.5 from 2 benchmarks, o3 70.7 from 2 benchmarks.
Widest category
Web design, 26.5 points apart on average over 5 shared benchmarks.
Widest single gap
ARC-AGI-2: Grok 4.5 52.6% against o3 6.5%, 46.1 points apart on a 0 to 100 scale.
Output price
Grok 4.5 $6.00 against o3 $8.00 per million output tokens, 1.3x apart.
Context window
Grok 4.5 takes 500K tokens, o3 200K.

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.

Boards won, where both have a result
CategoryGrok 4.5Barso3Ties
Coding41
Intelligence20
Reasoning122
Math40
Knowledge65
Web design50
General262
All shared boards5910
CodingLike-for-likeFour of these boards feed the Vibe Coding Index41
Coding benchmarks for Grok 4.5 and o3
BenchmarkGrok 4.5o3Leader
Aider polyglotNot measured81.3%Only o3 measured
SWE-bench VerifiedNot measured58.4%Only o3 measured
SWE-bench MultimodalNot measured36.0%Only o3 measured
LiveBench coding94.3%Not measuredOnly Grok 4.5 measured
LMArena WebDev1553Not measuredOnly Grok 4.5 measured
AA Coding Index72.4Not measuredOnly Grok 4.5 measured
LiveCodeBench (Vals AI)87.3%83.9%Grok 4.5
SWE-bench Verified (Vals AI)86.6%Not measuredOnly Grok 4.5 measured
Terminal-Bench 4 (Vals AI)8.6%Not measuredOnly Grok 4.5 measured
Vibe Code Bench (Vals AI)69.0%Not measuredOnly Grok 4.5 measured
Code migration (Vals AI)36.6%Not measuredOnly Grok 4.5 measured
ProgramBench (Vals AI)0.0%Not measuredOnly Grok 4.5 measured
IOI (Vals AI)40.6%Not measuredOnly Grok 4.5 measured
Terminal-Bench 2.1 (Vals AI)67.8%Not measuredOnly Grok 4.5 measured
SkillsBench (Vals AI)66.0%Not measuredOnly Grok 4.5 measured
CyberBench (Vals AI)71.0%Not measuredOnly Grok 4.5 measured
LiveCodeBench (Artificial Analysis run)Not measured80.8%Only o3 measured
SciCode55.0%Not measuredOnly Grok 4.5 measured
Terminal-Bench Hard (Artificial Analysis run)Not measured37.1%Only o3 measured
FrontierCode42.4%Not measuredOnly Grok 4.5 measured
GSO-BenchNot measured8.8%Only o3 measured
WeirdML46.4%52.4%o3
ALE-Bench1309.3933.5Grok 4.5
LMArena Text: coding14741407Grok 4.5
LMArena Text: software and IT14711415Grok 4.5
LMArena WebDev: React1556Not measuredOnly Grok 4.5 measured
LMArena WebDev: HTML1567Not measuredOnly Grok 4.5 measured
LMArena WebDev: from an image1562Not measuredOnly Grok 4.5 measured
Neither model has a result on the other 10 boards here
IntelligenceLike-for-likePublic boards, shown as published, kept out of the index20
Intelligence benchmarks for Grok 4.5 and o3
BenchmarkGrok 4.5o3Leader
AA Intelligence Index38.820.2Grok 4.5
Epoch Capabilities Index154.1146.7Grok 4.5
Agentic workDirectional onlyPublic boards, shown as published, kept out of the index27 boards, none shared
Agentic work benchmarks for Grok 4.5 and o3
BenchmarkGrok 4.5o3Leader
AA Agentic Index41.2Not measuredOnly Grok 4.5 measured
Design Arena: agents building web apps1217Not measuredOnly Grok 4.5 measured
Design Arena: agents building full-stack apps1249Not measuredOnly Grok 4.5 measured
Design Arena: agents building mobile apps1221Not measuredOnly Grok 4.5 measured
Design Arena: agents building Android apps1242Not measuredOnly Grok 4.5 measured
Design Arena: agents building Godot games1229Not measuredOnly Grok 4.5 measured
Design Arena: agents building games1235Not measuredOnly Grok 4.5 measured
Design Arena: HTML slides1204Not measuredOnly Grok 4.5 measured
Design Arena: PowerPoint slides1232Not measuredOnly Grok 4.5 measured
LiveBench research85.9%Not measuredOnly Grok 4.5 measured
LiveBench browser44.0%Not measuredOnly Grok 4.5 measured
LiveBench long agentic27.9%Not measuredOnly Grok 4.5 measured
SREBench (Vals AI)0.8%Not measuredOnly Grok 4.5 measured
Finance Agent (Vals AI)48.4%Not measuredOnly Grok 4.5 measured
Tax Agent Bench (Vals AI)24.9%Not measuredOnly Grok 4.5 measured
Legal Research Bench (Vals AI)38.0%Not measuredOnly Grok 4.5 measured
Excel Modeling Benchmark (Vals AI)52.9%Not measuredOnly Grok 4.5 measured
Time Horizon Index (Vals AI)6.3%Not measuredOnly Grok 4.5 measured
τ²-Bench TelecomNot measured80.7%Only o3 measured
APEX-Agents56.2%Not measuredOnly Grok 4.5 measured
METR time horizonsNot measured65.4%Only o3 measured
GDPvalNot measured30.8%Only o3 measured
DeepResearch BenchNot measured45.2%Only o3 measured
PostTrainBench23.4%Not measuredOnly Grok 4.5 measured
OSWorldNot measured23.0%Only o3 measured
Vending-Bench 2$3,887Not measuredOnly Grok 4.5 measured
LMArena Search1216Not measuredOnly Grok 4.5 measured
Neither model has a result on the other 12 boards here
ReasoningLike-for-likePublic boards, shown as published, kept out of the index122
Reasoning benchmarks for Grok 4.5 and o3
BenchmarkGrok 4.5o3Leader
GPQA Diamond92.9%84.1%Grok 4.5
LiveBench reasoning87.2%Not measuredOnly Grok 4.5 measured
MMMU Pro (Vals AI)61.8%80.4%o3
GPQA Diamond (Artificial Analysis run)93.1%82.7%Grok 4.5
Humanity's Last Exam (Artificial Analysis run)42.7%20.1%Grok 4.5
GPQA Diamond (Epoch AI run)93.4%81.8%Grok 4.5
ARC-AGI87.2%60.8%Grok 4.5
ARC-AGI-252.6%6.5%Grok 4.5
SimpleBench70.0%53.1%Grok 4.5
Chess puzzles35.0%37.0%o3
Mystery game puzzlesNot measured29.0%Only o3 measured
VPCTNot measured52.0%Only o3 measured
LMArena Text: hard prompts14621402Grok 4.5
LMArena Text: expert14651402Grok 4.5
LMArena Text: hard prompts in English14641411Grok 4.5
LMArena Vision: diagrams13041220Grok 4.5
LMArena Vision: homework12951234Grok 4.5
Neither model has a result on the other 4 boards here
MathLike-for-likePublic boards, shown as published, kept out of the index40
Math benchmarks for Grok 4.5 and o3
BenchmarkGrok 4.5o3Leader
AIMENot measured85.3%Only o3 measured
MATH 500 (Vals AI)Not measured94.6%Only o3 measured
MGSM (Vals AI)Not measured91.8%Only o3 measured
AA Math IndexNot measured88.3Only o3 measured
AIME 2025 (Artificial Analysis run)Not measured88.3%Only o3 measured
OTIS Mock AIME97.8%84.4%Grok 4.5
FrontierMath, tiers 1 to 357.2%33.3%Grok 4.5
FrontierMath, tier 424.4%Not measuredOnly Grok 4.5 measured
ProofBench31.0%Not measuredOnly Grok 4.5 measured
MATH level 5Not measured97.8%Only o3 measured
LMArena Text: math14601426Grok 4.5
LMArena Text: mathematical work14821423Grok 4.5
Neither model has a result on the other 1 board here
KnowledgeLike-for-likePublic boards, shown as published, kept out of the index65
Knowledge benchmarks for Grok 4.5 and o3
BenchmarkGrok 4.5o3Leader
MMLU Pro89.2%85.6%Grok 4.5
LegalBench (Vals AI)86.0%83.8%Grok 4.5
CorpFin (Vals AI)67.4%59.7%Grok 4.5
TaxEval (Vals AI)71.7%74.6%o3
MortgageTax (Vals AI)61.8%65.7%o3
MedQA (Vals AI)Not measured96.1%Only o3 measured
MedCode (Vals AI)43.3%47.3%o3
MMLU Pro (Artificial Analysis run)Not measured85.3%Only o3 measured
SimpleQA Verified48.3%49.4%o3
GeoBenchNot measured74.0%Only o3 measured
LMArena Text: science14641429Grok 4.5
LMArena Text: medicine and healthcare14401448o3
LMArena Text: legal and government14631428Grok 4.5
LMArena Text: business and finance14411393Grok 4.5
Neither model has a result on the other 3 boards here
Web designLike-for-likePublic boards, shown as published, kept out of the index50
Web design benchmarks for Grok 4.5 and o3
BenchmarkGrok 4.5o3Leader
Design Arena: websites12811036Grok 4.5
Design Arena: UI components12791016Grok 4.5
Design Arena: game dev12631034Grok 4.5
Design Arena: data viz12671200Grok 4.5
Design Arena: 3D1257Not measuredOnly Grok 4.5 measured
Design Arena: all code categories12761021Grok 4.5
Design Arena: SVG1215Not measuredOnly Grok 4.5 measured
Design Arena: ASCII art1257Not measuredOnly Grok 4.5 measured
LiveBench design78.1%Not measuredOnly Grok 4.5 measured
GeneralLike-for-likePublic boards, shown as published, kept out of the index262
General benchmarks for Grok 4.5 and o3
BenchmarkGrok 4.5o3Leader
LiveBench data analysis73.0%Not measuredOnly Grok 4.5 measured
SAGE (Vals AI)35.0%41.8%o3
MedScribe (Vals AI)86.9%76.7%Grok 4.5
Vals Multimodal Index63.4%Not measuredOnly Grok 4.5 measured
IFBenchNot measured71.4%Only o3 measured
Long context reasoning (AA-LCR)79.3%74.7%Grok 4.5
DTBench96.5%84.8%Grok 4.5
LMCA45.2%39.7%Grok 4.5
Fiction.LiveBenchNot measured88.9%Only o3 measured
Creative writing (Lech Mazur)Not measured83.9%Only o3 measured
CL-benchNot measured17.8%Only o3 measured
Surface Evolver Bench74.4%Not measuredOnly Grok 4.5 measured
Furniture assembly22.5%Not measuredOnly Grok 4.5 measured
LMArena Text14481410Grok 4.5
LMArena Text: instruction following14451368Grok 4.5
LMArena Text: creative writing14421359Grok 4.5
LMArena Vision12871214Grok 4.5
LMArena Text: English14531417Grok 4.5
LMArena Text: non-English14401401Grok 4.5
LMArena Text: Chinese14951437Grok 4.5
LMArena Text: German14481420Grok 4.5
LMArena Text: Japanese14301403Grok 4.5
LMArena Text: Korean14061370Grok 4.5
LMArena Text: French14571430Grok 4.5
LMArena Text: Spanish14511395Grok 4.5
LMArena Text: Russian14491406Grok 4.5
LMArena Text: Polish14321438o3
LMArena Text: multi-turn14561405Grok 4.5
LMArena Text: longer queries14621372Grok 4.5
LMArena Text: writing and language14451372Grok 4.5
LMArena Text: entertainment and media14341373Grok 4.5
LMArena Vision: English12851221Grok 4.5
LMArena Vision: Chinese13451237Grok 4.5
LMArena Vision: reading text12931218Grok 4.5
LMArena Vision: humor12761222Grok 4.5
LMArena Vision: captioningNot measured1210Only o3 measured
LMArena Vision: recognizing thingsNot measured1234Only o3 measured
LMArena Vision: creative writing12931201Grok 4.5
LMArena Document1452Not measuredOnly Grok 4.5 measured
Neither model has a result on the other 7 boards here
Image generationNot comparablePublic boards, shown as published, kept out of the index0 boards, none shared
Image generation benchmarks for Grok 4.5 and o3
BenchmarkGrok 4.5o3Leader
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

Grok 4.5$0.0050Fits in one request
o3$0.0060Fits in one request

Grok 4.5 costs less

Repository review

50K input + 3K output tokens

Grok 4.5$0.118Fits in one request
o3$0.124Fits in one request

Grok 4.5 costs less

Agent loop

200K input + 10K output tokens

Grok 4.5$0.460Fits in one request
o3$0.480Exceeds the context window

Grok 4.5 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.

Specifications of Grok 4.5 and o3
SpecificationSpaceXAI Grok 4.5OpenAI o3
MakerxAIOpenAI
WeightsNo public weights listedNo public weights listed
ReleasedJuly 8, 2026April 16, 2025
Context window500K200K
Input $/Mtok$2.00$2.00
Output $/Mtok$6.00$8.00
Coding index75.570.7
Independent measurements behind it22
Cost per solved task$0.62$0.571
SourceOpenRouter listingOpenRouter listing

Questions

Is Grok 4.5 better than o3 for coding?

Pick Grok 4.5 for coding: it scores 75.5 on the Vibe Coding Index against 70.7 for o3. Pick o3 when a solved task costs $0.571 against $0.62, or when what matters is WeirdML or MMMU Pro (Vals AI), where it leads.

Which is cheaper, Grok 4.5 or o3?

Grok 4.5 costs $2.00 per million input tokens and $6.00 per million output tokens; o3 costs $2.00 and $8.00. Per solved SWE-bench Verified task, Grok 4.5 costs $0.62 and o3 $0.571.

Which has the bigger context window, Grok 4.5 or o3?

Grok 4.5, with 500K tokens against 200K.

How many benchmarks is the Grok 4.5 vs o3 comparison based on?

69 benchmarks have a result for both models as of October 21, 2026. Grok 4.5's coding index rests on 2 independent benchmarks and o3's on 2. Where only one model has a result, the page says so instead of naming a winner.

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