Models, measured side by side
GPT-5.6 Sol vs GPT-6 Astra
Compare GPT-5.6 Sol, GPT-6 Astra by token pricing, context length, benchmark results, speed and tool support.
Monthly workload
Monthly cost breakdown
InputOutput
GPT-5.6 Sol
$90 / mo
GPT-6 Astra
$450 / mo
Performance comparison
GPT-5.6 Sol
47
GPT-6 Astra
52.7
Overview
Pricing & capacity
| Pricing & capacity | GPT-5.6 Sol | GPT-6 Astra |
|---|---|---|
| Input / 1M tokens | $2.00 | $10 |
| Output / 1M tokens | $10 | $50 |
| Cached input / 1M | $0.20 | $1.00 |
| Monthly cost | $90 | $450 |
| Context window | 1.1M | 1.1M |
| Maximum output | 128K | 128K |
Input / 1M tokens
- GPT-5.6 Sol
- $2.00
- GPT-6 Astra
- $10
Output / 1M tokens
- GPT-5.6 Sol
- $10
- GPT-6 Astra
- $50
Cached input / 1M
- GPT-5.6 Sol
- $0.20
- GPT-6 Astra
- $1.00
Monthly cost
- GPT-5.6 Sol
- $90
- GPT-6 Astra
- $450
Context window
- GPT-5.6 Sol
- 1.1M
- GPT-6 Astra
- 1.1M
Maximum output
- GPT-5.6 Sol
- 128K
- GPT-6 Astra
- 128K
Benchmarks & performance
| Benchmarks & performance | GPT-5.6 Sol | GPT-6 Astra |
|---|---|---|
| Arena Elo | 1,255 | 1,288 |
| MMLU-Pro | 82.8% | 88.3% |
| Intelligence Index | 47 | 52.7 |
| GPQA | 94.1% | 96.1% |
| Humanity’s Last Exam | 49.5% | 54.7% |
| SciCode | 57.1% | 56.5% |
| Output speed | 81 tokens/s | 60 tokens/s |
| Time to first token | 107.55 s | 287.74 s |
| DesignArena rating | 1,320 | 1,384 |
| DesignArena win rate | 56.8% | 64.8% |
Arena Elo
- GPT-5.6 Sol
- 1,255
- GPT-6 Astra
- 1,288
MMLU-Pro
- GPT-5.6 Sol
- 82.8%
- GPT-6 Astra
- 88.3%
Intelligence Index
- GPT-5.6 Sol
- 47
- GPT-6 Astra
- 52.7
GPQA
- GPT-5.6 Sol
- 94.1%
- GPT-6 Astra
- 96.1%
Humanity’s Last Exam
- GPT-5.6 Sol
- 49.5%
- GPT-6 Astra
- 54.7%
SciCode
- GPT-5.6 Sol
- 57.1%
- GPT-6 Astra
- 56.5%
Output speed
- GPT-5.6 Sol
- 81 tokens/s
- GPT-6 Astra
- 60 tokens/s
Time to first token
- GPT-5.6 Sol
- 107.55 s
- GPT-6 Astra
- 287.74 s
DesignArena rating
- GPT-5.6 Sol
- 1,320
- GPT-6 Astra
- 1,384
DesignArena win rate
- GPT-5.6 Sol
- 56.8%
- GPT-6 Astra
- 64.8%
Tools & features
| Tools & features | GPT-5.6 Sol | GPT-6 Astra |
|---|---|---|
| Function calling | Supported | Supported |
| Structured outputs | Supported | Supported |
| JSON mode | Supported | Supported |
| Reasoning | Supported | Supported |
| Deterministic seed | Supported | Supported |
| Prompt caching | Supported | Supported |
Function calling
- GPT-5.6 Sol
- Supported
- GPT-6 Astra
- Supported
Structured outputs
- GPT-5.6 Sol
- Supported
- GPT-6 Astra
- Supported
JSON mode
- GPT-5.6 Sol
- Supported
- GPT-6 Astra
- Supported
Reasoning
- GPT-5.6 Sol
- Supported
- GPT-6 Astra
- Supported
Deterministic seed
- GPT-5.6 Sol
- Supported
- GPT-6 Astra
- Supported
Prompt caching
- GPT-5.6 Sol
- Supported
- GPT-6 Astra
- Supported
API & availability
| API & availability | GPT-5.6 Sol | GPT-6 Astra |
|---|---|---|
| API identifier | gpt-5.6-sol | gpt-6-astra |
| API providers | OpenAI, OpenAI, OpenAI, Azure, Azure, Amazon Bedrock, Azure | OpenAI, Azure, OpenAI, Amazon Bedrock, Azure, OpenAI |
| Knowledge cutoff | 2026-02-16 | Not listed |
| Prices checked | Oct 8, 2026 | Oct 8, 2026 |
API identifier
- GPT-5.6 Sol
gpt-5.6-sol- GPT-6 Astra
gpt-6-astra
API providers
- GPT-5.6 Sol
- OpenAI, OpenAI, OpenAI, Azure, Azure, Amazon Bedrock, Azure
- GPT-6 Astra
- OpenAI, Azure, OpenAI, Amazon Bedrock, Azure, OpenAI
Knowledge cutoff
- GPT-5.6 Sol
- 2026-02-16
- GPT-6 Astra
- Not listed
Prices checked
- GPT-5.6 Sol
- Oct 8, 2026
- GPT-6 Astra
- Oct 8, 2026
About the models
GPT-5.6 Sol
Top GPT-5.6 model. Current price is promotional (down from $5 / $30), guaranteed at least through November 21, 2026. Long-context: $8 input / $30 output per 1M.
Full pricing & detailsGPT-6 Astra
OpenAI's flagship GPT-6 model for the hardest reasoning, coding and agentic work. Long-context requests (above 272K input tokens) bill at $20 input / $75 output per 1M.
Full pricing & detailsComparison FAQ
GPT-5.6 Sol: $2.00 input and $10 output per million tokens. GPT-6 Astra: $10 input and $50 output per million tokens. The cheaper choice depends on your input-to-output ratio; a model can have a lower input rate but a higher output rate.