Data points: 121
Model compare
The readout for GPT-5.3 Codex and Grok 4.3, before the detailed comparison sheet.
Weighted outcome: GPT-5.3 Codex. Benchmark capability categories carry 80%, while price, API performance, and availability carry 20%.
Decision read
GPT-5.3 Codex
GPT-5.3 Codex has the higher weighted result; Model A / B score 78.7 to 21.3.
Evidence depth
121 data points
Includes 29 benchmark rows, 0 audit samples, and 7 provider examples.
Selection signal
Start with GPT-5.3 Codex
The charts below split 36 high-signal samples across speed, scores, and audit health.
Switch either side of this report to compare another model with the same LMSpeed data pipeline.
Select a different model to open a new comparison URL.
This report only uses LMSpeed data for GPT-5.3 Codex and Grok 4.3: pricing, speed aggregates, third-party benchmark scores, and shared provider samples.
| Model compare | GPT-5.3 Codex | Grok 4.3 |
|---|---|---|
| Overall leader | Leading | Contender |
| Weighted overall score | 78.7 pts | 21.3 pts |
| Benchmark category leads | 5 categories | 1 categories |
| Operational advantages | Average speed, First-token latency, Provider coverage | Cheapest input price, Free providers |
| Context window | 400K tokens | 1M tokens |
| Max output | 128K tokens | No data |
| Modalities | Input TextImageFile Output Text |
The overall result weights benchmark capability categories at 80% and price, API speed/latency, and availability at 20%. Recent test volume does not affect the winner, and missing benchmark categories are excluded.
| Model compare | GPT-5.3 Codex | Grok 4.3 |
|---|---|---|
| Developer | OpenAI | xAI |
| Released | Feb 2026 | Apr 2026 |
| Parameters | No data | No data |
| Tokenizer | GPT | Grok |
| Knowledge cutoff | No data | No data |
| OpenRouter ID | openai/gpt-5.3-codex | x-ai/grok-4.3 |
| References | No data | No data |
This report only uses LMSpeed data for GPT-5.3 Codex and Grok 4.3: pricing, speed aggregates, third-party benchmark scores, and shared provider samples.
GPT-5.3 Codex
GPT-5.3 Codex is stronger in benchmark categories (Agents, Coding, Reasoning, Knowledge, Multimodal) and operational dimensions (Average speed, First-token latency, Provider coverage).
Grok 4.3
Grok 4.3 is stronger in benchmark categories (Instruction following) and operational dimensions (Cheapest input price, Free providers).
Third-party benchmark profile synced into LMSpeed; only metrics available for both models are shown.
Compare benchmark category scores on a 0-100 scale. Select a category to inspect the gap.
Avg. score
GPT-5.3 Codex
59.6
Avg. score
Grok 4.3
54.2
GPT-5.3 Codex leads by 3.8
GPT-5.3 Codex leads by 4.2
GPT-5.3 Codex leads by 4.4
GPT-5.3 Codex leads by 4.2
No data
GPT-5.3 Codex
GPT-5.3 Codex leads by 18.1
Grok 4.3 leads by 2.6
Metric-level scores with benchmark source, rank depth, confidence, error, and evaluation date where available.
GPT-5.3 Codex
winner82.0
Rank #11/127 · confidence 1 · eval date 2026-02-05
Grok 4.3
63.0
Rank #44/127 · confidence 1 · eval date 2026-04-30
GPT-5.3 Codex
95.6 tok/s
Rank #62/139 · confidence 4
Grok 4.3
winner115.5 tok/s
Rank #52/139 · confidence 4
GPT-5.3 Codex
69.67 s
Rank #128/139 · confidence 4
Grok 4.3
winner29.90 s
Rank #104/139 · confidence 4
GPT-5.3 Codex
69.67 s
Rank #132/139 · confidence 4
Grok 4.3
winner29.90 s
Rank #128/139 · confidence 4
GPT-5.3 Codex
$14.00/M
Rank #135/163 · confidence 4
Grok 4.3
winner$2.50/M
Rank #76/163 · confidence 4
GPT-5.3 Codex
$4.81/M
Rank #134/163 · confidence 4
Grok 4.3
winner$1.56/M
Rank #95/163 · confidence 4
GPT-5.3 Codex
$1.75/M
Rank #122/163 · confidence 4
Grok 4.3
winner$1.25/M
Rank #109/163 · confidence 4
GPT-5.3 Codex
winner74.0
Rank #5/89 · confidence 1 · eval date 2026-02-05
Grok 4.3
64.3
Rank #48/89 · confidence 1 · eval date 2026-04-30
GPT-5.3 Codex
winner91.5%
Rank #11/187 · confidence 4
Grok 4.3
90.1%
Rank #18/187 · confidence 4
GPT-5.3 Codex
winner16.9
Rank #12/73 · confidence 1 · eval date 2026-02-05
Grok 4.3
8.0
Rank #27/73 · confidence 1 · eval date 2026-04-30
GPT-5.3 Codex
winner39.9%
Rank #12/186 · confidence 4
Grok 4.3
35.0%
Rank #20/186 · confidence 4
GPT-5.3 Codex
winner87.0
Rank #6/100 · confidence 1 · eval date 2026-02-05
Grok 4.3
61.3
Rank #57/100 · confidence 1 · eval date 2026-04-30
GPT-5.3 Codex
winner53.0
Rank #9/85 · confidence 1 · eval date 2026-02-05
Grok 4.3
37.9
Rank #35/85 · confidence 1 · eval date 2026-04-30
GPT-5.3 Codex
winner53.2%
Rank #10/184 · confidence 4
Grok 4.3
47.3%
Rank #22/184 · confidence 4
GPT-5.3 Codex
winner53.2
Rank #14/96 · confidence 1 · eval date 2026-02-05
Grok 4.3
47.3
Rank #30/96 · confidence 1 · eval date 2026-04-30
GPT-5.3 Codex
winner89.0
Rank #4/92 · confidence 1 · eval date 2026-02-05
Grok 4.3
63.7
Rank #44/92 · confidence 1 · eval date 2026-04-30
GPT-5.3 Codex
winner51.8
Rank #8/90 · confidence 1 · eval date 2026-02-05
Grok 4.3
34.6
Rank #36/90 · confidence 1 · eval date 2026-04-30
GPT-5.3 Codex
9.9
Rank #15/29 · confidence 1 · eval date 2026-02-05
Grok 4.3
winner18.3
Rank #9/29 · confidence 1 · eval date 2026-04-30
GPT-5.3 Codex
winner39.9
Rank #11/96 · confidence 1 · eval date 2026-02-05
Grok 4.3
35.0
Rank #22/96 · confidence 1 · eval date 2026-04-30
GPT-5.3 Codex
winner91.5
Rank #12/96 · confidence 1 · eval date 2026-02-05
Grok 4.3
90.1
Rank #19/96 · confidence 1 · eval date 2026-04-30
GPT-5.3 Codex
winner44.3
Rank #16/99 · confidence 1 · eval date 2026-02-05
Grok 4.3
37.6
Rank #40/99 · confidence 1 · eval date 2026-04-30
GPT-5.3 Codex
winner86.9
Rank #23/90 · confidence 1 · eval date 2026-02-05
Grok 4.3
25.0
Rank #86/90 · confidence 1 · eval date 2026-04-30
GPT-5.3 Codex
winner91.5
Rank #2/81 · confidence 1 · eval date 2026-02-05
Grok 4.3
69.3
Rank #25/81 · confidence 1 · eval date 2026-04-30
GPT-5.3 Codex
winner78.5
Rank #14/57 · confidence 1 · eval date 2026-02-05
Grok 4.3
78.1
Rank #16/57 · confidence 1 · eval date 2026-04-30
GPT-5.3 Codex
1197.0
Rank #44/65 · confidence 1 · eval date 2026-02-05
Grok 4.3
winner1232.0
Rank #33/65 · confidence 1 · eval date 2026-04-30
GPT-5.3 Codex
75.4
Rank #21/86 · confidence 1 · eval date 2026-02-05
Grok 4.3
winner81.3
Rank #2/86 · confidence 1 · eval date 2026-04-30
GPT-5.3 Codex
87.8
Rank #11/75 · confidence 1 · eval date 2026-02-05
Grok 4.3
winner89.0
Rank #6/75 · confidence 1 · eval date 2026-04-30
GPT-5.3 Codex
86.0
Rank #41/84 · confidence 1 · eval date 2026-02-05
Grok 4.3
winner97.7
Rank #7/84 · confidence 1 · eval date 2026-04-30
GPT-5.3 Codex
winner57.5
Rank #13/50 · confidence 1 · eval date 2026-02-05
Grok 4.3
43.9
Rank #31/50 · confidence 1 · eval date 2026-04-30
Latest completed audits from shared providers, with four safety and integrity score groups plus report links.
| Provider | GPT-5.3 Codex | Grok 4.3 |
|---|---|---|
| No completed audits are available from shared providers yet. | ||
Speed aggregates and input/output pricing share each provider row for real API selection and migration cost checks.
| Provider | GPT-5.3 Codex | Grok 4.3 |
|---|---|---|
5 tests | GPT-5.3 Codex speed / latency 35 tok/s / 17640ms input / output No data | Grok 4.3 speed / latency N/A / N/A input / output No data |
5 tests | GPT-5.3 Codex speed / latency 22 tok/s / 3141ms input / output No data | Grok 4.3 speed / latency N/A / N/A input / output No data |
5 tests | GPT-5.3 Codex speed / latency N/A / N/A input / output No data | Grok 4.3 speed / latency 49 tok/s / 6488ms input / output No data |
5 tests | GPT-5.3 Codex speed / latency 45 tok/s / 6276ms input / output No data | Grok 4.3 speed / latency N/A / N/A input / output No data |
5 tests | GPT-5.3 Codex speed / latency 242 tok/s / 2952ms input / output No data | Grok 4.3 speed / latency N/A / N/A input / output No data |
GPT-5.3 Codex gpt-5.3-codex speed / latency No data input / output $0/M/$0/M | Grok 4.3 grok-4.3-fast speed / latency No data input / output $75.00/M | |
GPT-5.3 Codex gpt-5.3-codex speed / latency No data input / output $0/request | Grok 4.3 grok-4.3 speed / latency No data input / output $0/request |
Weighted outcome: GPT-5.3 Codex. Benchmark capability categories carry 80%, while price, API performance, and availability carry 20%.
Input
Output
| Features | Text inputImage inputFile inputText outputTool callingStructured outputsJSON modeReasoning | Text inputImage inputFile inputText outputTool callingStructured outputsJSON modeReasoning |
|---|
