# Gemini 3.8 Flash vs o3

Gemini 3.8 Flash is the cheaper of the 2: for the same tokens, 3 read for each 1 written, o3 costs 2.3 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-o3
- Makers: Gemini 3.8 Flash from Google, o3 from OpenAI

## Price per million tokens, in US dollars

| | Gemini 3.8 Flash | o3 |
| --- | --: | --: |
| Input | $0.75 | $2 |
| Cached input | $0.075 | $0.50 |
| Cache write | not listed | not listed |
| Output | $3.75 | $8 |
| Blend, 3 read for each 1 written | $1.50 | $3.50 |
| Batch input | not listed | $1 |
| Batch output | not listed | $4 |
| Context window, tokens | 1.05M | 200K |
| Capability score (Epoch Capabilities Index; GPT-5 is 150) | 157 | 147 |
| Longest answer, tokens | 66K | 100K |

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.
- o3: 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 | o3 |
| --- | --- | --: | --: |
| A chat question | 300, 500, 100 | $6.30 | $13.80 |
| A hard question, with thinking | 300, 1,400, 100 | $16.43 | $35.40 |
| A long report, summarised | 60,000, 2,000, 20 | $31.50 | $81.60 |
| A 40-turn agent task | 2,800,000, 40,000, 10 | $165 | $642 |
| A support bot's reply | 4,000, 300, 2,000 | $166 | $444 |
| Sort a message into a category | 250, 5, 50,000 | $309 | $810 |
| Read an invoice into fields | 1,500, 250, 1,000 | $61.88 | $150 |
| Review a pull request | 25,000, 4,500, 50 | $53.44 | $129 |

## Questions

### Which is cheaper, Gemini 3.8 Flash or o3?

Gemini 3.8 Flash is cheaper: $0.75 per million tokens read and $3.75 per million written, against $2 and $8 on o3. On a mix of 3 tokens read for each 1 written, o3 costs 2.3 times as much.

### Which is better, Gemini 3.8 Flash or o3?

On the Epoch Capabilities Index, an independent score from Epoch AI that combines over 50 benchmarks, Gemini 3.8 Flash scores 157 and o3 147, above the top of the range of doubt around o3'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 o3?

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 $444 on o3: o3 costs 2.7 times as much for this job.

### What does an AI agent task cost on Gemini 3.8 Flash and o3?

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 $2.14 on o3. At 10 tasks a day that is $165 and $642 a month.

### Which has the larger context window, Gemini 3.8 Flash or o3?

Gemini 3.8 Flash, with 1.05M tokens against 200K on o3. 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 o3?

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 o3. 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 o3 for work that can wait?

On o3 only: with a batch, where you collect the answers later, it costs $1 per million tokens read and $4 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 o3](https://tecyfy.com/prices/compare/gpt-6-astra-vs-o3.md)
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- [GPT-6 Luna vs o3](https://tecyfy.com/prices/compare/gpt-6-luna-vs-o3.md)
- [Gemini 3.6 Flash vs Gemini 3.8 Flash](https://tecyfy.com/prices/compare/gemini-3-6-flash-vs-gemini-3-8-flash.md)
- [Gemini 3.1 Pro Preview vs Gemini 3.8 Flash](https://tecyfy.com/prices/compare/gemini-3-1-pro-preview-vs-gemini-3-8-flash.md)
- [Gemini 3.1 Flash-Lite vs Gemini 3.8 Flash](https://tecyfy.com/prices/compare/gemini-3-1-flash-lite-vs-gemini-3-8-flash.md)