tokcount › gpt-4o
GPT-4o token counter.
Count tokens for GPT-4o, GPT-4o mini, GPT-5, o3, and o4-mini. Free, browser-only. No API key. No signup. Exact token count using the same o200k_base encoding OpenAI charges for.
$ npm i -g @v0idd0/tokcount
# one-time install
$ tokcount prompt.md --model gpt-4o
model: gpt-4o · encoding: o200k_base · tokens: 3,817 · cost: $0.0095 in + $0.0382 out
$ tokcount context.md --model gpt-4o-mini
model: gpt-4o-mini · tokens: 3,817 · cost: $0.0006 in + $0.0023 out
$ tokcount prompt.md --model gpt-4o --all --tag openai
# cost comparison across all OpenAI models at once
✓ 3,817 tokens · 3.0% of 128K context
OpenAI API pricing — 2026.
tokcount calculates input and output costs automatically. Cached input pricing is 50% off — use --cache flag.
GPT-4o — most used
gpt-4o
context: 128K · output: 16K
input$2.50 / 1M
output$10.00 / 1M
encodingo200k_base
GPT-4o mini
gpt-4o-mini
context: 128K · output: 16K
input$0.15 / 1M
output$0.60 / 1M
encodingo200k_base
o3
o3
context: 200K · output: 100K
input$10.00 / 1M
output$40.00 / 1M
encodingo200k_base
Pricing from OpenAI's public API docs. All models use o200k_base encoding. Exact counts — identical to tiktoken output.
Count GPT-4o tokens in the browser.
The tokcount browser extension shows live token counts as you type inside ChatGPT — including system prompt, conversation history, images, and remaining context budget before you hit the limit.
CLI —
tokcount- exact BPE counts via o200k_base
- multi-model cost table (
--all) - pipe-friendly for build scripts
- JSON output mode (
--json)
Extension — live in ChatGPT
- inline count as you type
- context window % used
- cost estimate per message
- Chrome + Firefox + Edge
GPT-4o tokenization — FAQ.
Is tokcount as accurate as tiktoken for GPT-4o?
Yes. tokcount uses gpt-tokenizer, a JavaScript port of tiktoken that produces byte-exact results for GPT-4o using the o200k_base encoding. The count you get from
tokcount --model gpt-4o is identical to what OpenAI's API bills you for. This is not an estimate — it uses the same BPE vocabulary file.What encoding does GPT-4o use?
GPT-4o uses o200k_base encoding — an updated vocabulary from the earlier cl100k_base used by GPT-4 and GPT-3.5. The main difference: o200k_base has a larger vocabulary (200,000 tokens vs 100,000) which results in slightly fewer tokens for most text, especially code and structured data.
What is GPT-4o's token and context limit?
GPT-4o has a 128,000-token context window (input + conversation history) and a 16,384-token maximum output length. o3 extends input to 200,000 tokens. tokcount warns you when your input approaches these limits and shows context utilization as a percentage.
How much does GPT-4o cost compared to GPT-4o mini?
GPT-4o costs $2.50/1M input and $10.00/1M output. GPT-4o mini costs $0.15/1M input and $0.60/1M output — roughly 17× cheaper. For a typical 4,000-token prompt + 500-token output: GPT-4o costs about $0.015; GPT-4o mini costs about $0.001. Run
tokcount prompt.md --model gpt-4o --all --tag openai to see the full OpenAI cost comparison at once.Do images count as tokens in GPT-4o?
Yes, but tokcount counts only text tokens. GPT-4o Vision bills images separately based on resolution: low-detail = 85 tokens flat; high-detail = 85 + 170 per 512×512 tile. tokcount does not include image tokens in its count — for prompts with images, add the image token estimate manually.
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