# GPT-5.5 pro vs GPT-6 Astra

GPT-6 Astra is one of OpenAI's newest models and GPT-5.5 pro an earlier one, so this is also what moving up costs or saves. GPT-6 Astra is the cheaper of the 2: for the same tokens, 3 read for each 1 written, GPT-5.5 pro costs 3.4 times as much. Below are both price lists, what 8 everyday jobs cost a month on each, and how many tokens the same text takes on each, which can change the answer.

- Page, with a calculator for your own job: https://tecyfy.com/prices/compare/gpt-5-5-pro-vs-gpt-6-astra
- Makers: GPT-5.5 pro from OpenAI, GPT-6 Astra from OpenAI

## Price per million tokens, in US dollars

| | GPT-5.5 pro | GPT-6 Astra |
| --- | --: | --: |
| Input | $30 | $10 |
| Cached input | not listed | $1 |
| Cache write | not listed | $12.50 |
| Output | $180 | $50 |
| Blend, 3 read for each 1 written | $67.50 | $20 |
| Batch input | $15 | $5 |
| Batch output | $90 | $25 |
| Long prompt input (above 272K on GPT-5.5 pro, 272K on GPT-6 Astra) | $60 | $20 |
| Long prompt output | $270 | $75 |
| Context window, tokens | 1.05M | 1.05M |
| Capability score (Epoch Capabilities Index; GPT-5 is 150) | 162 | 166 |
| Longest answer, tokens | 128K | 128K |

## What 8 everyday jobs cost a month on each

Each job at its usual runs a day, for 30 days, at the standard price.

| Job | Tokens in, out, runs a day | GPT-5.5 pro | GPT-6 Astra |
| --- | --- | --: | --: |
| A chat question | 300, 500, 100 | $297 | $84.00 |
| A hard question, with thinking | 300, 1,400, 100 | $783 | $219 |
| A long report, summarised | 60,000, 2,000, 20 | $1,296 | $420 |
| A 40-turn agent task | 2,800,000, 40,000, 10 | $27,360 | $2,196 |
| A support bot's reply | 4,000, 300, 2,000 | $10,440 | $2,220 |
| Sort a message into a category | 250, 5, 50,000 | $12,600 | $4,125 |
| Read an invoice into fields | 1,500, 250, 1,000 | $2,700 | $825 |
| Review a pull request | 25,000, 4,500, 50 | $2,340 | $713 |

## Questions

### Which is cheaper, GPT-5.5 pro or GPT-6 Astra?

GPT-6 Astra is cheaper: $10 per million tokens read and $50 per million written, against $30 and $180 on GPT-5.5 pro. On a mix of 3 tokens read for each 1 written, GPT-5.5 pro costs 3.4 times as much.

### Which is better, GPT-5.5 pro or GPT-6 Astra?

On the Epoch Capabilities Index, an independent score from Epoch AI that combines over 50 benchmarks, GPT-6 Astra scores 166 and GPT-5.5 pro 162, above the top of the range of doubt around GPT-5.5 pro's score (GPT-5 is 150). One score is an average; test both on your own work before you switch.

### What does a support bot cost a month on GPT-5.5 pro and GPT-6 Astra?

At 2,000 replies a day, each reading 4,000 tokens (50 percent of them from cache) and writing 300, it costs $10,440 a month on GPT-5.5 pro and $2,220 on GPT-6 Astra: GPT-5.5 pro costs 4.7 times as much for this job.

### What does an AI agent task cost on GPT-5.5 pro and GPT-6 Astra?

One 40-turn task that reads 2,800,000 tokens in all, 90 percent of them from cache, and writes 40,000, costs $91.20 on GPT-5.5 pro and $7.32 on GPT-6 Astra. At 10 tasks a day that is $27,360 and $2,196 a month.

### Which has the larger context window, GPT-5.5 pro or GPT-6 Astra?

Neither: both hold 1.05M tokens at once, about 1,575 pages of English text.

### Does the same text take the same number of tokens on GPT-5.5 pro and GPT-6 Astra?

Yes, both are counted the same way: our lesson "How AI writes", 1,700 words long, is about 2,100 tokens on each.

### Is it cheaper to move from GPT-5.5 pro to GPT-6 Astra?

Yes, per token: GPT-6 Astra costs $10 per million tokens read and $50 written, against $30 and $180 on GPT-5.5 pro, which costs 3.4 times as much for the same tokens. Run your own tasks on it before you switch, since answers, length and thinking can differ.

### Can I pay less on GPT-5.5 pro and GPT-6 Astra for work that can wait?

Yes, on both. With a batch, where you collect the answers later instead of at once, GPT-5.5 pro costs $15 per million tokens read and $90 written, and GPT-6 Astra $5 and $25.

## Sources

- [OpenAI: API prices](https://developers.openai.com/api/docs/pricing)
- [Epoch Capabilities Index, by Epoch AI (CC BY 4.0)](https://epoch.ai/benchmarks/eci)

## Other comparisons

- [GPT-6 Astra vs GPT-6 Sol](https://tecyfy.com/prices/compare/gpt-6-astra-vs-gpt-6-sol.md)
- [GPT-5.6 Sol vs GPT-6 Astra](https://tecyfy.com/prices/compare/gpt-5-6-sol-vs-gpt-6-astra.md)
- [GPT-5.6 Terra vs GPT-6 Astra](https://tecyfy.com/prices/compare/gpt-5-6-terra-vs-gpt-6-astra.md)
- [GPT-5.6 Luna vs GPT-6 Astra](https://tecyfy.com/prices/compare/gpt-5-6-luna-vs-gpt-6-astra.md)
- [GPT-5.5 vs GPT-6 Astra](https://tecyfy.com/prices/compare/gpt-5-5-vs-gpt-6-astra.md)
- [GPT-5.5 pro vs GPT-6.1 Sol](https://tecyfy.com/prices/compare/gpt-5-5-pro-vs-gpt-6-1-sol.md)