Data points: 94
Model compare
The readout for GPT-5.3 Codex and Grok 4.20, 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 96 to 4.
Evidence depth
94 data points
Includes 15 benchmark rows, 0 audit samples, and 7 provider examples.
Selection signal
Start with GPT-5.3 Codex
The charts below split 22 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 4.20: pricing, speed aggregates, third-party benchmark scores, and shared provider samples.
| Model compare | GPT-5.3 Codex | Grok 4.20 |
|---|---|---|
| Overall leader | Leading | Contender |
| Weighted overall score | 96.0 pts | 4.0 pts |
| Benchmark category leads | 4 categories | 0 categories |
| Operational advantages | Average speed, First-token latency, Free providers, Provider coverage | Cheapest input price |
| Context window | 400K tokens | 2M 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 4.20 |
|---|---|---|
| Developer | OpenAI | xAI |
| Released | Feb 2026 | Mar 2026 |
| Parameters | No data | No data |
| Tokenizer | GPT | Grok |
| Knowledge cutoff | No data | 2025-09-01 |
| OpenRouter ID | openai/gpt-5.3-codex | x-ai/grok-4.20 |
| References | No data | No data |
This report only uses LMSpeed data for GPT-5.3 Codex and Grok 4.20: 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) and operational dimensions (Average speed, First-token latency, Free providers, Provider coverage).
Grok 4.20
Grok 4.20 has these operational advantages: Cheapest input price.
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
56.5
Avg. score
Grok 4.20
45.1
GPT-5.3 Codex leads by 9.8
GPT-5.3 Codex leads by 11.4
GPT-5.3 Codex leads by 8.4
GPT-5.3 Codex leads by 10.9
No data
No data
Grok 4.20
GPT-5.3 Codex
Metric-level scores with benchmark source, rank depth, confidence, error, and evaluation date where available.
GPT-5.3 Codex
winner64.0
Rank #22/84 · confidence 1 · eval date 2026-02-05
Grok 4.20
46.0
Rank #65/84 · confidence 2 · eval date 2026-03-10
GPT-5.3 Codex
$14.00/M
Rank #133/162 · confidence 4
Grok 4.20
winner$6.00/M
Rank #105/162 · confidence 4
GPT-5.3 Codex
$4.81/M
Rank #132/162 · confidence 4
Grok 4.20
winner$3.00/M
Rank #112/162 · confidence 4
GPT-5.3 Codex
winner$1.75/M
Rank #120/162 · confidence 4
Grok 4.20
$2.00/M
Rank #123/162 · confidence 4
GPT-5.3 Codex
winner91.5%
Rank #12/188 · confidence 4
Grok 4.20
91.1%
Rank #14/188 · confidence 4
GPT-5.3 Codex
winner39.9%
Rank #13/187 · confidence 4
Grok 4.20
32.2%
Rank #29/187 · confidence 4
GPT-5.3 Codex
winner61.8
Rank #4/33 · confidence 1 · eval date 2026-02-05
Grok 4.20
4.1
Rank #30/33 · confidence 2 · eval date 2026-03-10
GPT-5.3 Codex
winner85.0
Rank #5/43 · confidence 1 · eval date 2026-02-05
Grok 4.20
76.7
Rank #23/43 · confidence 2 · eval date 2026-03-10
GPT-5.3 Codex
winner53.2%
Rank #11/185 · confidence 4
Grok 4.20
45.6%
Rank #34/185 · confidence 4
GPT-5.3 Codex
winner58.5
Rank #19/65 · confidence 1 · eval date 2026-02-05
Grok 4.20
44.1
Rank #49/65 · confidence 2 · eval date 2026-03-10
GPT-5.3 Codex
winner56.8
Rank #20/37 · confidence 1 · eval date 2026-02-05
Grok 4.20
51.8
Rank #32/37 · confidence 2 · eval date 2026-03-10
GPT-5.3 Codex
1193.0
Rank #46/66 · confidence 1 · eval date 2026-02-05
Grok 4.20
winner1257.0
Rank #29/66 · confidence 2 · eval date 2026-03-10
GPT-5.3 Codex
winner77.3
Rank #10/46 · confidence 1 · eval date 2026-02-05
Grok 4.20
47.1
Rank #40/46 · confidence 2 · eval date 2026-03-10
GPT-5.3 Codex
winner57.5
Rank #13/50 · confidence 1 · eval date 2026-02-05
Grok 4.20
38.4
Rank #42/50 · confidence 2 · eval date 2026-03-10
GPT-5.3 Codex
winner64.3
Rank #23/53 · confidence 1 · eval date 2026-02-05
Grok 4.20
30.2
Rank #44/53 · confidence 2 · eval date 2026-03-10
Latest completed audits from shared providers, with four safety and integrity score groups plus report links.
| Provider | GPT-5.3 Codex | Grok 4.20 |
|---|---|---|
| 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 4.20 |
|---|---|---|
65 tests | GPT-5.3 Codex speed / latency 38 tok/s / 4553ms input / output No data | Grok 4.20 speed / latency 67 tok/s / 1296ms input / output No data |
15 tests | GPT-5.3 Codex speed / latency N/A / N/A input / output No data | Grok 4.20 speed / latency 103 tok/s / 9875ms input / output No data |
15 tests | GPT-5.3 Codex speed / latency 201 tok/s / 2135ms input / output No data | Grok 4.20 speed / latency 55 tok/s / 1168ms input / output No data |
10 tests | GPT-5.3 Codex speed / latency N/A / N/A input / output No data | Grok 4.20 speed / latency 82 tok/s / 10813ms input / output No data |
5 tests | GPT-5.3 Codex speed / latency 35 tok/s / 17640ms input / output No data | Grok 4.20 speed / latency N/A / N/A input / output No data |
GPT-5.3 Codex gpt-5.3-codex-openai-compact speed / latency No data input / output $0/M/$0/M | Grok 4.20 grok-4.20-fast speed / latency No data input / output $0/M | |
GPT-5.3 Codex gpt-5.3-codex-spark speed / latency No data input / output $26.25/M/$210.00/M | Grok 4.20 grok-4.20-fast speed / latency No data input / output $0.012/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 |
|---|
