Context window fit check
ClientPaste a draft and pick a context window size to see rough usage, remaining budget, and overflow. Complements context split & budget.
Draft text
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Token counts use the same CJK-aware chars/token heuristic as the token estimate page. Reserve headroom for tools, images, and tokenizer drift.
- Characters
- 157
- Rough tokens
- 40
- Remaining
- 127,960
- Status
- Fits
Nearby workflows on Toolcore
- LLM token estimate — Rough character-based token planning for prompts and context—CJK-aware heuristic, browser-only—not tokenizer-exact. when you want a second pass with AI-assisted explanation on Toolcore.
- LLM context split & budget — Split pasted prompt blocks by a delimiter and see per-section rough token share and optional budget compare—browser-only, not tokenizer-exact. when you want a second pass with AI-assisted explanation on Toolcore.
- Long text chunker for chat paste — Split long pasted prose into sequential under-the-limit blocks—paragraph, line, or fixed character breaks—browser-only; not tokenizer-exact. when you want a second pass with AI-assisted explanation on Toolcore.
- LLM character budget from token cap — Plan max paste characters from a target token budget—same CJK-aware heuristic as token estimate, browser-only, not tokenizer-exact. when you want a second pass with AI-assisted explanation on Toolcore.
Common use cases
- Check if a RAG bundle plus system prompt still fits a 128K window before sending.
- Switch between 8K, 32K, and 200K presets when comparing model tiers.
- Spot overflow early and trim with long text chunker or whitespace savings.
Common mistakes to avoid
Ignoring tool definitions and image tokens
This counts pasted text only—reserve extra budget for tools, JSON schema, and vision payloads.
Assuming 100% fill is safe
Leave headroom for the model reply and tokenizer drift; aim below ~85% for drafts.
FAQ
Is this the official tokenizer?
No. It uses the same CJK-aware character heuristic as our token estimate page.
Does text leave my browser?
No. Statistics are computed locally.
More tools
Related utilities you can open in another tab—mostly client-side.
LLM token estimate
ClientRough character-based token planning for prompts and context—CJK-aware heuristic, browser-only—not tokenizer-exact.
LLM context split & budget
ClientSplit pasted prompt blocks by a delimiter and see per-section rough token share and optional budget compare—browser-only, not tokenizer-exact.
Long text chunker for chat paste
ClientSplit long pasted prose into sequential under-the-limit blocks—paragraph, line, or fixed character breaks—browser-only; not tokenizer-exact.
LLM character budget from token cap
ClientPlan max paste characters from a target token budget—same CJK-aware heuristic as token estimate, browser-only, not tokenizer-exact.