ChatGPT Custom Instructions Limit: 1,500 Characters Per Field
ChatGPT custom instructions are capped at 1,500 characters per field, per the OpenAI Help Center (June 2026). Custom GPTs built in the GPT builder allow 8,000 characters of instructions. Gemini Gems accept roughly 4,000 characters, with Google recommending 500 to 2,000. Claude Projects publish no hard character cap; instructions simply count against the 200,000-token context window. Paste your draft into our character counter before saving to see exactly where you stand.