Data points: 100
Model compare
GPT-4o vs GPT-5.5
The readout for GPT-4o and GPT-5.5, before the detailed comparison sheet.
Key Takeaways
Weighted outcome: GPT-5.5. Benchmark capability categories carry 80%, while price, API performance, and availability carry 20%.
Decision read
GPT-5.5
GPT-5.5 has the higher weighted result; Model A / B score 8 to 92.
Evidence depth
100 data points
Includes 17 benchmark rows, 0 audit samples, and 10 provider examples.
Selection signal
Start with GPT-5.5
The charts below split 27 high-signal samples across speed, scores, and audit health.
Change comparison
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.
Comparison sheet
This report only uses LMSpeed data for GPT-4o and GPT-5.5: pricing, speed aggregates, third-party benchmark scores, and shared provider samples.
| Model compare | GPT-4o | GPT-5.5 |
|---|---|---|
| Overall leader | Contender | Leading |
| Weighted overall score | 8.0 pts | 92.0 pts |
| Benchmark category leads | 0 categories | 6 categories |
| Operational advantages | Average speed, First-token latency | Cheapest input price, Free providers, Provider coverage |
| Context window | 128K tokens | 1.1M tokens |
| Max output | 16.4K tokens | 128K tokens |
| Modalities | Input TextImageFile Output Text | Input FileImageText Output Text |
| Features | Text inputImage inputFile inputText outputTool callingStructured outputsJSON modeWeb search | Text inputImage inputFile inputText outputTool callingStructured outputsJSON modeReasoning |
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 metadata
Model metadata
| Model compare | GPT-4o | GPT-5.5 |
|---|---|---|
| Developer | OpenAI | OpenAI |
| Released | Nov 2024 | Apr 2026 |
| Parameters | No data | No data |
| Tokenizer | GPT | GPT |
| Knowledge cutoff | 2023-10-31 | 2025-12-01 |
| OpenRouter ID | openai/gpt-4o | openai/gpt-5.5 |
| References | No data | No data |
When to choose each model
This report only uses LMSpeed data for GPT-4o and GPT-5.5: pricing, speed aggregates, third-party benchmark scores, and shared provider samples.
GPT-4o
GPT-4o has these operational advantages: Average speed, First-token latency.
GPT-5.5
GPT-5.5 is stronger in benchmark categories (Agents, Coding, Reasoning, Knowledge, Math) and operational dimensions (Cheapest input price, Free providers, Provider coverage).
Benchmark score comparison
Third-party benchmark profile synced into LMSpeed; only metrics available for both models are shown.
Category performance
Compare benchmark category scores on a 0-100 scale. Select a category to inspect the gap.
- Model A coverage
- 6 / 8
- Model B coverage
- 7 / 8
- Shared
- 6 shared categories
Avg. score
GPT-4o
42.4
Avg. score
GPT-5.5
57.7
Agents
GPT-5.5 leads by 22.3
Coding
GPT-5.5 leads by 15.9
Reasoning
GPT-5.5 leads by 18.9
Knowledge
GPT-5.5 leads by 9.7
Math
GPT-5.5 leads by 14.0
Multilingual
No data
Multimodal
GPT-5.5
Instruction following
GPT-5.5 leads by 13.1
Professional benchmark details
Metric-level scores with benchmark source, rank depth, confidence, error, and evaluation date where available.
Professional benchmark details
Metric-level scores with benchmark source, rank depth, confidence, error, and evaluation date where available.
GPT-4o
43.0
Rank #103/111 · confidence 1 · eval date 2024-05-13
GPT-5.5
winner69.0
Rank #20/111 · confidence 4 · eval date 2026-04-23
GPT-4o
winner$10.00/M
Rank #142/186 · confidence 4
GPT-5.5
$30.00/M
Rank #174/186 · confidence 4
GPT-4o
winner$4.38/M
Rank #149/186 · confidence 4
GPT-5.5
$11.25/M
Rank #174/186 · confidence 4
GPT-4o
winner$2.50/M
Rank #154/186 · confidence 4
GPT-5.5
$5.00/M
Rank #168/186 · confidence 4
GPT-4o
54.3%
Rank #184/218 · confidence 4
GPT-5.5
winner93.5%
Rank #7/218 · confidence 4
GPT-4o
2.4%
Rank #214/216 · confidence 4
GPT-5.5
winner45.8%
Rank #15/216 · confidence 4
GPT-4o
33.3
Rank #96/113 · confidence 1 · eval date 2024-05-13
GPT-5.5
winner55.8
Rank #16/113 · confidence 4 · eval date 2026-04-23
GPT-4o
0.3
Rank #47/47 · confidence 1 · eval date 2024-05-13
GPT-5.5
winner51.7
Rank #4/47 · confidence 4 · eval date 2026-04-23
GPT-4o
25.2
Rank #61/63 · confidence 1 · eval date 2024-05-13
GPT-5.5
winner69.6
Rank #21/63 · confidence 4 · eval date 2026-04-23
GPT-4o
19.9
Rank #90/106 · confidence 1 · eval date 2024-05-13
GPT-5.5
winner58.0
Rank #6/106 · confidence 4 · eval date 2026-04-23
GPT-4o
54.3
Rank #107/113 · confidence 1 · eval date 2024-05-13
GPT-5.5
winner93.5
Rank #8/113 · confidence 4 · eval date 2026-04-23
GPT-4o
2.4
Rank #114/114 · confidence 1 · eval date 2024-05-13
GPT-5.5
winner45.8
Rank #13/114 · confidence 4 · eval date 2026-04-23
GPT-4o
37.9
Rank #89/106 · confidence 1 · eval date 2024-05-13
GPT-5.5
winner89.0
Rank #22/106 · confidence 4 · eval date 2026-04-23
GPT-4o
11.1
Rank #107/117 · confidence 1 · eval date 2024-05-13
GPT-5.5
winner38.6
Rank #30/117 · confidence 4 · eval date 2026-04-23
GPT-4o
842.0
Rank #77/78 · confidence 1 · eval date 2024-05-13
GPT-5.5
winner1270.0
Rank #30/78 · confidence 4 · eval date 2026-04-23
GPT-4o
34.3
Rank #80/84 · confidence 1 · eval date 2024-05-13
GPT-5.5
winner75.9
Rank #13/84 · confidence 4 · eval date 2026-04-23
GPT-4o
25.1
Rank #73/82 · confidence 1 · eval date 2024-05-13
GPT-5.5
winner98.0
Rank #8/82 · confidence 4 · eval date 2026-04-23
API audit comparison
Latest completed audits from shared providers, with four safety and integrity score groups plus report links.
API audit comparison
Latest completed audits from shared providers, with four safety and integrity score groups plus report links.
| Provider | GPT-4o | GPT-5.5 |
|---|---|---|
| No completed audits are available from shared providers yet. | ||
Provider examples
Speed aggregates and input/output pricing share each provider row for real API selection and migration cost checks.
Provider examples
Speed aggregates and input/output pricing share each provider row for real API selection and migration cost checks.
| Provider | GPT-4o | GPT-5.5 |
|---|---|---|
速创API20 tests | GPT-4o speed / latency 88 tok/s / 1593ms input / output No data | GPT-5.5 speed / latency N/A / N/A input / output No data |
9527 API10 tests | GPT-4o speed / latency N/A / N/A input / output No data | GPT-5.5 speed / latency 52 tok/s / 2732ms input / output No data |
DeepKey API10 tests | GPT-4o speed / latency N/A / N/A input / output No data | GPT-5.5 speed / latency 43 tok/s / 2874ms input / output No data |
Fengsili API5 tests | GPT-4o speed / latency N/A / N/A input / output No data | GPT-5.5 speed / latency 58 tok/s / 3313ms input / output No data |
KFCV505 tests | GPT-4o speed / latency 48 tok/s / 13138ms input / output No data | GPT-5.5 speed / latency N/A / N/A input / output No data |
GPT-4o gpt-4o speed / latency No data input / output $0/M/$0/M | GPT-5.5 gpt-5.5 speed / latency No data input / output $0/M/$0/M | |
GPT-4o gpt-4o speed / latency No data input / output $0/M/$0/M | GPT-5.5 gpt-5-5 speed / latency No data input / output $0/M/$0/M | |
GPT-4o gpt-4o speed / latency No data input / output $0/request | GPT-5.5 gpt-5.5-high speed / latency No data input / output $0/request | |
GPT-4o gpt-4o-all speed / latency No data input / output $0.0066/request | GPT-5.5 gpt-5.5-2026-04-23 speed / latency No data input / output $0.685/M/$4.11/M | |
GPT-4o gpt-4o-all speed / latency No data input / output $0.0066/request | GPT-5.5 gpt-5.5 speed / latency No data input / output $0.685/M/$5.48/M |
FAQ
Weighted outcome: GPT-5.5. Benchmark capability categories carry 80%, while price, API performance, and availability carry 20%.
- Why is this comparison indexable?
- It has 6 verifiable comparison points, and both models have pricing or benchmark data.
- Are missing metrics invented?
- No. Metrics without LMSpeed data are omitted from this report.