AI Token Estimator
Paste your prompt and instantly estimate token counts and API costs across Claude, GPT-4o, and Gemini. Runs entirely in your browser — your text never leaves your device.
Pricing disclaimer: Cost estimates use approximate published rates and may be outdated. Always verify current pricing on the provider's official pricing page before making budget decisions.
How Token Estimation Works
Large language models process text as tokens, not characters or words. A token is roughly 3–4 characters of English text, a common word, or a punctuation mark. Models are billed per token consumed, so estimating tokens before making API calls helps you control costs and fit within context window limits.
This tool uses a BPE-style (Byte Pair Encoding) heuristic that estimates tokens from character and word boundaries. For typical English prose it stays within 5–10% of the actual tokenizer count. Code, special characters, and non-Latin scripts may have higher variance.
Context Window vs. Max Output
Each model has a maximum context window — the total tokens it can process in one request (input + output combined). If your prompt alone is large, you may have limited room left for the model's response. The progress bars above show what fraction of each model's context window your input text would consume.
Model Comparison
| Model | Context | Input / 1M | Output / 1M | Best for |
|---|---|---|---|---|
| Claude Sonnet 4 | 200K | ~$3.00 | ~$15.00 | Complex tasks, coding, analysis |
| Claude Haiku 4 | 200K | ~$0.80 | ~$4.00 | Fast, affordable, high-volume |
| GPT-4o | 128K | ~$2.50 | ~$10.00 | Multimodal, broad compatibility |
| GPT-4o mini | 128K | ~$0.15 | ~$0.60 | Low-cost, high-throughput |
| Gemini 1.5 Pro | 1M | ~$1.25 | ~$5.00 | Very long documents, RAG |
| Gemini 1.5 Flash | 1M | ~$0.075 | ~$0.30 | Budget-friendly, large context |
Prices are approximate and subject to change. Verify at the provider's official pricing page before making cost decisions.