# Gemini 3.5 Flash-Lite vs o3-mini

Gemini 3.5 Flash-Lite is the cheaper of the 2: for the same tokens, 3 read for each 1 written, o3-mini 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-3-5-flash-lite-vs-o3-mini
- Makers: Gemini 3.5 Flash-Lite from Google, o3-mini from OpenAI

## Price per million tokens, in US dollars

| | Gemini 3.5 Flash-Lite | o3-mini |
| --- | --: | --: |
| Input | $0.30 | $1.10 |
| Cached input | $0.03 | $0.55 |
| Cache write | not listed | not listed |
| Output | $2.50 | $4.40 |
| Blend, 3 read for each 1 written | $0.85 | $1.925 |
| Batch input | not listed | $0.55 |
| Batch output | not listed | $2.20 |
| Context window, tokens | 1.05M | 200K |
| Capability score (Epoch Capabilities Index; GPT-5 is 150) | 145 | 140 |
| Longest answer, tokens | 66K | 100K |

## 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 3.5 Flash-Lite: 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-mini: 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 3.5 Flash-Lite | o3-mini |
| --- | --- | --: | --: |
| A chat question | 300, 500, 100 | $4.02 | $7.59 |
| A hard question, with thinking | 300, 1,400, 100 | $10.77 | $19.47 |
| A long report, summarised | 60,000, 2,000, 20 | $13.80 | $44.88 |
| A 40-turn agent task | 2,800,000, 40,000, 10 | $77.88 | $561 |
| A support bot's reply | 4,000, 300, 2,000 | $84.60 | $277 |
| Sort a message into a category | 250, 5, 50,000 | $131 | $446 |
| Read an invoice into fields | 1,500, 250, 1,000 | $32.25 | $82.50 |
| Review a pull request | 25,000, 4,500, 50 | $28.13 | $70.95 |

## Questions

### Which is cheaper, Gemini 3.5 Flash-Lite or o3-mini?

Gemini 3.5 Flash-Lite is cheaper: $0.30 per million tokens read and $2.50 per million written, against $1.10 and $4.40 on o3-mini. On a mix of 3 tokens read for each 1 written, o3-mini costs 2.3 times as much.

### Which is better, Gemini 3.5 Flash-Lite or o3-mini?

On the Epoch Capabilities Index, an independent score from Epoch AI that combines over 50 benchmarks, Gemini 3.5 Flash-Lite scores 145 and o3-mini 140, above the top of the range of doubt around o3-mini'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 3.5 Flash-Lite and o3-mini?

At 2,000 replies a day, each reading 4,000 tokens (50 percent of them from cache) and writing 300, it costs $84.60 a month on Gemini 3.5 Flash-Lite and $277 on o3-mini: o3-mini costs 3.3 times as much for this job.

### What does an AI agent task cost on Gemini 3.5 Flash-Lite and o3-mini?

One 40-turn task that reads 2,800,000 tokens in all, 90 percent of them from cache, and writes 40,000, costs 26 cents on Gemini 3.5 Flash-Lite and $1.87 on o3-mini. At 10 tasks a day that is $77.88 and $561 a month.

### Which has the larger context window, Gemini 3.5 Flash-Lite or o3-mini?

Gemini 3.5 Flash-Lite, with 1.05M tokens against 200K on o3-mini. 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 3.5 Flash-Lite and o3-mini?

No. Our lesson "How AI writes", 1,700 words long, is about 2,200 tokens on Gemini 3.5 Flash-Lite and about 2,100 on o3-mini. 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 3.5 Flash-Lite and o3-mini for work that can wait?

On o3-mini only: with a batch, where you collect the answers later, it costs $0.55 per million tokens read and $2.20 written. Google's price page lists no batch price for Gemini 3.5 Flash-Lite.

## 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)

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