# Gemini 3.8 Flash vs GPT-6 Astra

Gemini 3.8 Flash is the cheaper of the 2: for the same tokens, 3 read for each 1 written, GPT-6 Astra costs 13 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/gemini-3-8-flash-vs-gpt-6-astra
- Makers: Gemini 3.8 Flash from Google, GPT-6 Astra from OpenAI

## Price per million tokens, in US dollars

| | Gemini 3.8 Flash | GPT-6 Astra |
| --- | --: | --: |
| Input | $0.75 | $10 |
| Cached input | $0.075 | $1 |
| Cache write | not listed | $12.50 |
| Output | $3.75 | $50 |
| Blend, 3 read for each 1 written | $1.50 | $20 |
| Batch input | not listed | $5 |
| Batch output | not listed | $25 |
| Long prompt input (above 272K on GPT-6 Astra) | $0.75 | $20 |
| Long prompt output | $3.75 | $75 |
| Context window, tokens | 1.05M | 1.05M |
| Capability score (Epoch Capabilities Index; GPT-5 is 150) | 157 | 166 |
| Longest answer, tokens | 66K | 128K |

Gemini 3.8 Flash: Until 31 December 2026. From 1 January 2027 it is $1.50 in, $7.50 out and $0.15 cached.

## The same text, counted by each maker

Our lesson "How AI writes" (https://tecyfy.com/learn/how-ai-works/how-ai-writes), about 1,700 words of English:

- Gemini 3.8 Flash: about 2,200 tokens. Google does not publish the Gemini tokenizer. Its rule is that a token is about 4 characters, so the count is the characters divided by 4.
- GPT-6 Astra: about 2,100 tokens. GPT-5.6 is counted with o200k_base, the tokenizer OpenAI publishes for it, so its count is exact. OpenAI has not published the tokenizer of GPT-6, so its count is the same o200k_base figure, marked as about.

## 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 | Gemini 3.8 Flash | GPT-6 Astra |
| --- | --- | --: | --: |
| A chat question | 300, 500, 100 | $6.30 | $84.00 |
| A hard question, with thinking | 300, 1,400, 100 | $16.43 | $219 |
| A long report, summarised | 60,000, 2,000, 20 | $31.50 | $420 |
| A 40-turn agent task | 2,800,000, 40,000, 10 | $165 | $2,196 |
| A support bot's reply | 4,000, 300, 2,000 | $166 | $2,220 |
| Sort a message into a category | 250, 5, 50,000 | $309 | $4,125 |
| Read an invoice into fields | 1,500, 250, 1,000 | $61.88 | $825 |
| Review a pull request | 25,000, 4,500, 50 | $53.44 | $713 |

## Questions

### Which is cheaper, Gemini 3.8 Flash or GPT-6 Astra?

Gemini 3.8 Flash is cheaper: $0.75 per million tokens read and $3.75 per million written, against $10 and $50 on GPT-6 Astra. On a mix of 3 tokens read for each 1 written, GPT-6 Astra costs 13 times as much.

### Which is better, Gemini 3.8 Flash 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 Gemini 3.8 Flash 157, above the top of the range of doubt around Gemini 3.8 Flash'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 Gemini 3.8 Flash 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 $166 a month on Gemini 3.8 Flash and $2,220 on GPT-6 Astra: GPT-6 Astra costs 13 times as much for this job.

### What does an AI agent task cost on Gemini 3.8 Flash 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 55 cents on Gemini 3.8 Flash and $7.32 on GPT-6 Astra. At 10 tasks a day that is $165 and $2,196 a month.

### Which has the larger context window, Gemini 3.8 Flash or GPT-6 Astra?

GPT-6 Astra, with 1.05M tokens against 1.05M on Gemini 3.8 Flash. The window holds your instructions, the files you attach, the conversation so far and the answer, all at once.

### Does the same text take the same number of tokens on Gemini 3.8 Flash and GPT-6 Astra?

No. Our lesson "How AI writes", 1,700 words long, is about 2,200 tokens on Gemini 3.8 Flash and about 2,100 on GPT-6 Astra. Each maker cuts text its own way, and every extra token is paid for at the model's price.

### Can I pay less on Gemini 3.8 Flash and GPT-6 Astra for work that can wait?

On GPT-6 Astra only: with a batch, where you collect the answers later, it costs $5 per million tokens read and $25 written. Google's price page lists no batch price for Gemini 3.8 Flash.

## Sources

- [Google: API prices](https://ai.google.dev/gemini-api/docs/pricing)
- [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 Astra](https://tecyfy.com/prices/compare/gpt-5-5-pro-vs-gpt-6-astra.md)