GPT-4o Token Counter (Exact o200k_base)
Exact token counts for GPT-4o and GPT-4.1. No upload, no sign-up.
Loading tokenizer…
Paste any text and instantly see how many tokens it uses for GPT-4o. This page uses OpenAI's real o200k_base tokenizer, so the count matches the API exactly. Your prompt is never uploaded. No sign-up, no credits, no limits.
- Exact API match
- Supports GPT-4.1
- 128k context window
- No upload
- Runs offline
How many tokens is my GPT-4o prompt?
Paste your prompt into the box above. It is counted exactly with OpenAI's o200k_base tokenizer, the exact same tokenizer used for GPT-4o and GPT-4.1. The count updates as you type and nothing is uploaded. Use this to estimate costs or check if your prompt fits inside the 128k context window.
- Price
- Free, no credits, no sign-up
- Tokenizer
- o200k_base (Exact same as OpenAI API)
- Models covered
- GPT-4o and GPT-4.1
- Context Window
- 128,000 tokens
- Text uploaded to server
- No, runs 100% in your browser
- Input
- Any plain text, code, JSON or conversation
- Extras
- Characters, words, lines, chars-per-token ratio
- Best browsers
- Any modern browser (Chrome, Edge, Firefox, Safari)
- Works offline
- Yes, after the first load
- Not included
- Cost-per-1K calculator, batch file upload, saved history
What is the GPT-4o token counter?
This is a free, browser-based tool that counts tokens specifically for GPT-4o and GPT-4.1. It uses the `o200k_base` tokenizer, which is exact. Unlike tools that guess or use older tokenizers, the number you see here is exactly what OpenAI will charge you for. It also reports characters, words, lines and the chars-per-token ratio. No file is uploaded, no account is required and the tool works offline after the first load.
It is best for prompt engineering, API cost estimation, system prompt budgeting, and ensuring your long documents fit inside the 128k context window. It is not built for counting image tokens (Vision) or calculating exact dollar amounts, because model prices change often.
How to count GPT-4o tokens in 3 steps
- 1
Paste your text
Paste your prompt, text document, or code into the box. The tool counts as you type using the exact o200k_base tokenizer.
- 2
Check the count
Read the exact token count, plus characters, words, and chars-per-token ratio. GPT-4o is already pre-selected.
- 3
Send to the API
Adjust your prompt to fit your context window or budget, then send it. The count will match the API perfectly.
Features
100% Exact Token Counts
Uses OpenAI's real o200k_base tokenizer. The number you see here is the exact same number the API will return in `usage.prompt_tokens`. No estimates or average multipliers.
Supports GPT-4.1
OpenAI uses the same o200k_base tokenizer for GPT-4o and the newer GPT-4.1 models. You can confidently use this tool to estimate costs for both.
Check 128k Context Windows
GPT-4o and GPT-4.1 have a 128,000 token context window. Paste long documents to verify they fit before you send them to the API and trigger a "context length exceeded" error.
Live Character & Word Counts
See characters, words, lines, and the chars-per-token ratio alongside the token count. This helps you estimate the size of your prompt before you even send it.
Runs Entirely Locally
The tokenizer loads via JavaScript, so every count happens on your device. Your prompts, proprietary code, and API keys never leave your browser.
Clean, Fast Interface
No ads, no popups, no sign-up. Just paste your text, read the number, and go back to building. Works perfectly on desktop and mobile.
What you can use the GPT-4o counter for
Staying under the 128k limit
GPT-4o can handle a lot of text, but long PDFs, codebases, or chat histories can still overflow. Paste your prompt here first to ensure it fits.
Accurate cost estimation
Because the count is exact, you can multiply it by the GPT-4o input price per token and get a precise cost estimate before making thousands of API calls.
Trimming bloated prompts
Write two versions of a system prompt and compare their exact token counts. The shorter version is cheaper, faster, and often gets the same result.
Checking code token usage
Code uses more tokens per character than English due to brackets, punctuation, and indentation. Paste your snippet to see its true o200k_base count.
RAG pipeline budgeting
Sum your system prompt, retrieved chunks, and user message to check how many tokens you spend per turn. Make sure you leave room for the model's output tokens.
Verifying API billing
If your API bill seems high, paste the exact text you sent. If the count is much higher than you expected, you might be sending hidden whitespace or redundant context.
GPT-4o Token Counter FAQ
Answers about accuracy, context windows, pricing, and how o200k_base differs from older models.
GPT-4o Accuracy
Does this match the OpenAI API exactly?
Yes. We use the official o200k_base tokenizer, which is exactly what OpenAI uses for GPT-4o and GPT-4.1. The number you see here will match the `usage.prompt_tokens` returned by the API.
Why does GPT-4o give a different count than GPT-4?
They use different tokenizers. GPT-4o and GPT-4.1 use o200k_base, while GPT-4 and GPT-3.5 use cl100k_base. The o200k_base tokenizer has a larger vocabulary (200k vs 100k tokens), which makes it more efficient, especially for non-English text and code.
Does this count system prompt tokens?
Yes. Any text you paste into the box is counted. If you paste your system prompt and your user message together, you will get the total count for that request.
Is my prompt saved or logged?
No. The tokenizer runs entirely in your browser via JavaScript. Your text is never sent to ToolDeck servers, and it disappears when you close or refresh the page.
Context Window & Cost
What is GPT-4o's context window?
GPT-4o has a 128,000 token context window. This means the combined total of your input prompt and the model's output cannot exceed 128k tokens. GPT-4.1 also supports a 1 million token context window in some API tiers.
How do I calculate the cost?
Find the current price per 1,000 tokens for GPT-4o (it is usually different for input and output). Multiply your token count by the input price to get the cost per request. ToolDeck does not display dollar amounts because prices change frequently.
What happens if I exceed 128k tokens?
The API will return an error and the request will fail. You must trim your prompt, remove older chat history, or split the task into smaller chunks.
Tokens vs Characters
How many characters is 1 token?
For plain English, 1 token is roughly 4 characters. However, code, math, and non-English languages use more tokens per character. Look at the "Chars / token" stat to see the exact ratio for your text.
How many words is 128k tokens?
Roughly 96,000 words of plain English. That is about the length of a short novel. For code or non-English text, the word count will be much lower.
What this tool does well, and where it is limited
This page is locked to o200k_base. Check this table to see if it fits your use case.
| Use case | Result | Notes |
|---|---|---|
| Counting GPT-4o and GPT-4.1 tokens | Exact | Uses OpenAI's real o200k_base tokenizer, so the number matches the API's usage.prompt_tokens. |
| Counting GPT-4 or GPT-3.5 tokens | Use different page | Older models use cl100k_base. This page is hardcoded to o200k_base, so switch to the main Token Counter or OpenAI Token Counter for those. |
| Counting Claude tokens | Not supported here | This page is strictly for o200k_base (GPT-4o). Use the Claude Token Counter for Claude approximations. |
| Counting very long text (over 100k tokens) | Works, may lag | Browsers can count large inputs but the UI may pause while the tokenizer runs. Split the text if you hit freezes. |
| Cost per 1K tokens | Not calculated here | Multiply the token count by the GPT-4o price per 1K tokens yourself. Prices change often. |
| Counting image tokens (Vision) | Not supported | Image tokens are calculated based on resolution and detail level, not plain text. This tool only counts text. |
Tips
Remember the 128k limit
GPT-4o has a 128,000 token limit for the combined input and output. If your input is 120k tokens, you only have 8k left for the model's response.
Code uses more tokens
A line of minified JSON or dense Python code uses far more tokens per character than plain English. Always paste code directly to get the exact count.
Empty space counts
Spaces, newlines, and tabs all count as tokens. Removing unnecessary whitespace or pretty-printing can save a few tokens per request.
Compare with older models
o200k_base is much more efficient for non-English languages than the old cl100k_base. A paragraph in Japanese will use far fewer tokens on this page than on the GPT-3.5 counter.
ToolDeck vs other token counters
Many generic token counters use older tokenizers (cl100k_base) and give you the wrong number for GPT-4o. ToolDeck uses the exact match.
| Feature | ToolDeck | Generic counters |
|---|---|---|
| Uses exact o200k_base tokenizer | Yes, matches API | Often cl100k_base or guesswork |
| Supports GPT-4o and GPT-4.1 | Yes | Varies by tool |
| Your text is uploaded to a server | Never | Usually yes |
| Sign-up needed | Not required | Often |
| Free credits or paywalls | None | Often |
| Real-time counting as you type | Yes | Usually yes |
| Character, word and line counts | Yes | Sometimes |
| Works offline after loading | Yes | Usually no |
General comparison. Individual tools differ, and features, limits and pricing change.
Responsible use
The counter is a reference tool. Always confirm the exact count with the provider's API before you depend on it in production. Prices and tokenizers change; this page is updated when they do.
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Your prompts never leave your device
There is no upload step and no account. The tokenizer runs in your browser, so every count happens on your own device. You can check this yourself: open your browser developer tools, go to the Network tab, then paste text and watch for file uploads. You will not see any. Read how we keep it private.