vs
3:15
overall capability wins (2 ties across 20 scored). GPT-5.6 Sol leads overall.
- Reasoning2:5
- Coding1:6
- Arena0:1
- Agents0:1
- Tool use0:1
- Math0:1
- Composite indices0:2
- Pricing0:3
- Speed0:2
Verdict
GPT-5.6 Sol leads coding (widest gap: +107.2 on WebDev Elo); GPT-5.6 Sol ranks higher on LMArena (+7 Elo); GPT-5.6 Sol is ~1.4x cheaper on a blended token basis than GPT-5.5.
- GPT-5.6 Sol leads coding (widest gap: +107.2 on WebDev Elo)
- GPT-5.6 Sol ranks higher on LMArena (+7 Elo)
- GPT-5.6 Sol is ~1.4x cheaper on a blended token basis than GPT-5.5
Cost for 1M in + 250K out
Illustrative chat workload at primary-provider list prices.
- GPT-5.5
- $12.50
- GPT-5.6 Sol
- $9
GPT-5.6 Sol is about 1.4x cheaper on this workload.
Price per 1M tokens
Full comparison
Organization
OpenAI
OpenAI
Family
GPT-5.x
GPT-5.x
License
Proprietary
Proprietary
Open weights
No
No
Release
Apr 23, 2026
Jul 9, 2026
Knowledge cutoff
-
2026-02-16
API / provider
OpenAI
OpenAI
Modalities
text, image → text
text, image → text
Specs
Context window
1.1M
1.1M
Max output
128K
128K
Parameters
—
—
Pricing
Input $/1M
$5
$4
Output $/1M
$30
$20
Blended $/1M (3∶1)
$11.25
$8
Speed
tok/s
70
96
TTFT (s)
0.5
0.45
Reasoning
MMLU-Pro
—
—
GPQA Diamond
93.5
94.1
Humanity's Last Exam
45.8
49.5
AIME 2025
—
—
MATH-500
—
—
Humanity's Last Exam (with tools)
—
—
AA-Omniscience Accuracy
58.0
59.4
AA-LCR v1.1
84.3
84.0
CritPt
27.1
32.3
MMMU-Pro
79.9
83.4
IFBench
75.9
72.7
Chartography
—
—
Chartography (With Tools)
—
—
Coding
SWE-bench Verified
—
—
SWE-bench Pro
58.6
64.6
SWE-bench Multilingual
—
—
LiveCodeBench
—
—
Terminal-Bench 2.1
84.3
88.0
Aider Polyglot
—
—
Terminal-Bench 3
—
34.6
BigCodeBench
—
—
SciCode
55.8
57.1
CursorBench
58.4
67.2
SWE-Rebench
62.7
62.3
NL2Repo-Bench
—
—
DeepSWE
67.0
72.7
WebDev Arena
1,510
1,617
Terminal-Bench 4.0
—
37.3
CursorBench 4.0
—
—
FrontierCode v1.1 (Main)
—
—
Arena
LMArena Elo
1,476
1,484
| Metric | GPT-5.5 | GPT-5.6 Sol | Delta |
|---|---|---|---|
| Identity | |||
| Organization | OpenAI | OpenAI | — |
| Family | GPT-5.x | GPT-5.x | — |
| License | Proprietary | Proprietary | — |
| Open weights | No | No | — |
| Release | Apr 23, 2026 | Jul 9, 2026 | — |
| Knowledge cutoff | - | 2026-02-16 | — |
| API / provider | OpenAI | OpenAI | — |
| Modalities | text, image → text | text, image → text | — |
| Specs | |||
| Context window | 1.1M | 1.1M | tie |
| Max output | 128K | 128K | tie |
| Parameters | — | — | — |
| Pricing | |||
| Input $/1M | $5 | $4 | B +$1 |
| Output $/1M | $30 | $20 | B +$10 |
| Blended $/1M (3∶1) | $11.25 | $8 | B +$3.25 |
| Speed | |||
| tok/s | 70 | 96 | B +26 |
| TTFT (s) | 0.5 | 0.45 | B +0.05 |
| Reasoning | |||
| MMLU-Pro | — | — | — |
| GPQA Diamond | 93.5 | 94.1 | B +0.6 pts |
| Humanity's Last Exam | 45.8 | 49.5 | B +3.7 pts |
| AIME 2025 | — | — | — |
| MATH-500 | — | — | — |
| Humanity's Last Exam (with tools) | — | — | — |
| AA-Omniscience Accuracy | 58.0 | 59.4 | B +1.4 pts |
| AA-LCR v1.1 | 84.3 | 84.0 | A +0.3 pts |
| CritPt | 27.1 | 32.3 | B +5.2 pts |
| MMMU-Pro | 79.9 | 83.4 | B +3.5 pts |
| IFBench | 75.9 | 72.7 | A +3.2 pts |
| Chartography | — | — | — |
| Chartography (With Tools) | — | — | — |
| Coding | |||
| SWE-bench Verified | — | — | — |
| SWE-bench Pro | 58.6 | 64.6 | B +6.0 pts |
| SWE-bench Multilingual | — | — | — |
| LiveCodeBench | — | — | — |
| Terminal-Bench 2.1 | 84.3 | 88.0 | B +3.7 pts |
| Aider Polyglot | — | — | — |
| Terminal-Bench 3 | — | 34.6 | — |
| BigCodeBench | — | — | — |
| SciCode | 55.8 | 57.1 | B +1.3 pts |
| CursorBench | 58.4 | 67.2 | B +8.8 pts |
| SWE-Rebench | 62.7 | 62.3 | A +0.4 pts |
| NL2Repo-Bench | — | — | — |
| DeepSWE | 67.0 | 72.7 | B +5.7 pts |
| WebDev Arena | 1,510 | 1,617 | B +107 Elo |
| Terminal-Bench 4.0 | — | 37.3 | — |
| CursorBench 4.0 | — | — | — |
| FrontierCode v1.1 (Main) | — | — | — |
| Arena | |||
| LMArena Elo | 1,476 | 1,484 | B +7 Elo |
GPT-5.5
- Context
- 1.1M / 128K out
- Parameters
- —
- Price
- $5 / $30
- Speed
- 70 tok/s · 0.5s TTFT
- Modalities
- text, image → text
- License
- Proprietary
Prior OpenAI flagship with strong coding and long context; still widely used alongside the newer 5.6 family.
GPT-5.6 Sol
- Context
- 1.1M / 128K out
- Parameters
- —
- Price
- $4 / $20
- Speed
- 96 tok/s · 0.45s TTFT
- Modalities
- text, image → text
- License
- Proprietary
OpenAI's July 2026 flagship reasoning tier, tuned for hard STEM and agentic work; ChatGPT's top API SKU in the 5.6 family. Promotional Standard rates are $4/$20 (through at least Nov 21, 2026). Fast mode (2× price) delivers up to 2.5× Standard speed, and the Cerebras-powered Ultrafast preview reaches up to 750 tok/s.
Benchmark charts
Winner bars are emphasized. Per-benchmark deltas sit above each chart.