Custom instructions give ChatGPT a standing set of preferences to consider when it responds. They are useful for choices that should remain consistent across conversations, such as your preferred tone, reading level, units, formatting habits, or the kind of context you regularly need. On July 15, 2026, OpenAI increased the available space for some paid and organizational plans from 1,500 to 5,000 characters. The larger field makes room for clearer guidance, but it does not turn custom instructions into a private database or a guarantee that every response will follow every line.
This guide explains who receives the larger limit, what custom instructions affect, how to write them well, and what to consider before storing ongoing context. It is based on OpenAI’s current help documentation and release notes, not on personal product testing.
Who can use the 5,000-character limit?
OpenAI’s Custom Instructions help article lists two limits. Plus, Pro, Enterprise, Business, and Education users can save up to 5,000 characters. Free and Go users can save up to 1,500 characters. Custom instructions themselves are available on all plans across web, desktop, iOS, and Android; the difference is how much text each eligible account can store.
The July 15, 2026 release note describes the increase as a change from 1,500 to 5,000 characters for the five eligible plan groups. It says the added room is intended to support more customization of response style and behavior. It does not announce 5,000 characters for Free or Go accounts, so users on those plans should design within the documented 1,500-character allowance.
A character limit counts more than visible words. Spaces and punctuation also occupy space. You do not need to fill the field, and a shorter set of specific instructions is often easier to maintain than a long policy document.
What custom instructions change
OpenAI describes custom instructions as information you want ChatGPT to consider in its responses. That can cover stable preferences and recurring context. For example, you might ask for plain English, metric units, concise answers first, code examples in a particular language, or a short explanation of unfamiliar terms.
These instructions act as background guidance. They do not replace the request you type in a chat. A useful division is to keep durable preferences in custom instructions and put task-specific details in the current prompt. If you are writing one grant application, the grant rules belong in that conversation. If you always want dates written in ISO format, that may belong in custom instructions.
OpenAI says updates are applied immediately across chats, including existing conversations. In practice, that means subsequent responses can use the new version. Earlier messages are not rewritten. The help article also notes that previous versions may remain visible in chat history. Removing or editing the setting controls future responses, while clearing an old conversation is the documented way to remove old instruction text that appears in that conversation.
How to find and control the setting
Use the path documented for your platform rather than relying on an old screenshot. On web and desktop, OpenAI directs users to Settings, then Personalization. Make sure Enable customization is on and enter the text in the Custom Instructions field. On iOS and Android, open Settings, select Customize ChatGPT, turn on Enable customization, and enter the instructions in the same named field.
You can disable the feature without immediately deleting the saved text. On mobile, turn Enable customization off under Customize ChatGPT. On web and desktop, go through Personalization and Custom Instructions, then turn the setting off. OpenAI presents deletion as an optional separate step. If you only want to compare behavior temporarily, disabling first is less destructive than erasing a carefully edited set.
Design instructions around stable decisions
The extra space works best when it removes repeated setup rather than adding a biography. Start by listing decisions you make in many chats. Then keep only the ones that would still be useful a month from now.
A practical structure is:
- Context: your role or audience, limited to details that materially change an answer.
- Response preferences: tone, depth, units, language, accessibility needs, or preferred output format.
- Working rules: how to handle uncertainty, assumptions, citations, calculations, or code.
- Boundaries: habits you do not want, such as invented sources, unnecessary jargon, or a conclusion that repeats the introduction.
Write each line so that another person could tell whether it was followed. “Write well” gives little direction. “Use short paragraphs, define technical terms on first use, and put the answer before background” is easier to interpret. Avoid packing several unrelated requirements into one sentence. If two rules conflict, revise them instead of hoping the model will decide which one matters more.
A reusable example for everyday work
The following is an original example, not an official OpenAI template:
I work with a mixed technical and nontechnical audience. Start with a direct answer, then add the reasoning needed to act on it. Use plain English and short paragraphs. Define specialized terms the first time they appear. Use metric units and ISO dates. When information is uncertain, state the uncertainty and identify what would confirm it. Do not invent quotations, sources, test results, or product behavior. For recommendations, explain the main tradeoff instead of presenting one choice as universally best. Use tables only when they make comparison easier.
This example is compact because each sentence addresses a recurring choice. It does not include a current project name, client data, a temporary deadline, or the contents of a document. Those belong in the relevant conversation, where they can be removed from the standing context later.
Use the larger field without creating contradictions
Five thousand characters can support more detail, but length is not a quality score. Long instructions often fail for ordinary editorial reasons: the same idea appears twice, exceptions are scattered, or a new rule conflicts with an old one.
Group related requirements and put the most important ones first. Prefer a clear default with one necessary exception. For example, “Answer concisely by default; give a detailed derivation when I ask for one” is more coherent than separate commands demanding both maximum detail and maximum brevity.
Keep examples limited to cases that clarify a rule. Ten formatting samples can consume space while making the intended default less obvious. If a project needs extensive terminology, a long rubric, or many source documents, keep that material with the project or conversation instead of turning account-wide instructions into a storage area.
Privacy, data use, and sensitive permanent context
Custom instructions persist as account-level settings, so treat them as ongoing context rather than a disposable prompt. Do not store passwords, API keys, payment details, private medical records, confidential client material, or other information that does not need to be present in every chat.
OpenAI says custom instructions are not shared with viewers of a shared link. It also warns that when third-party plug-ins are used, the model may give plug-in developers relevant information from the instructions. OpenAI therefore advises using only plug-ins you trust and excluding information you would not want provided to those developers.
The help article says information from the use of custom instructions may be used to improve model performance and links to OpenAI’s training opt-out information. Review your account’s Data Controls if you do not want your content used for that purpose. The same help page confirms that custom instructions are included in a ChatGPT data export.
Deleting the setting and deleting the account are different actions. You can edit or delete instructions for future conversations at any time. If you delete your OpenAI account, OpenAI says associated custom-instruction data is deleted within 30 days as part of that process. It also notes that chat records may have been de-identified and disassociated from the account if you had not opted out of content use.
If you want a broader look at related personalization controls, read our guide to ChatGPT memory and its controls. For account-level privacy choices, our ChatGPT training opt-out guide covers that separate setting.
What custom instructions cannot guarantee
Custom instructions shape responses, but they do not verify facts, create new product permissions, or make unsafe information appropriate to share. A line asking for citations does not prove that a citation is real. A request for accurate calculations does not remove the need to check consequential results. Review important output against reliable sources.
The feature is also separate from the API. OpenAI’s help article says there is no custom-instructions API and directs API developers to use system messages for a similar effect in the Chat Completions API. Do not assume that text saved in the ChatGPT interface automatically becomes configuration for an API application.
Custom instructions can also collide with a direct prompt or with each other. When the output becomes awkward, inspect the standing rules before blaming the current question. A requirement to avoid lists may conflict with a request for a checklist. A general preference for brief answers may be a poor fit for a detailed contract comparison. The current task still needs enough context to resolve exceptions.
How to revise your instructions
Review the setting when your role, audience, tools, or writing needs change. A simple revision process keeps the text useful:
- Save a private copy of the current text if you may want to restore it.
- Remove outdated project names, repeated rules, and context that no longer affects most chats.
- Turn vague preferences into observable instructions.
- Resolve pairs that ask for opposite behavior.
- Disable customization briefly if you need to compare responses without the standing guidance.
- After editing, use future responses to see whether the important defaults are clear. Revise the instruction itself rather than adding more exceptions to every prompt.
Do not treat one imperfect answer as proof that the entire setup needs another thousand characters. First check whether the relevant rule was specific, whether the current prompt supplied the needed facts, and whether another standing instruction competed with it.
Frequently asked questions
Does every ChatGPT plan get 5,000 characters?
No. OpenAI currently documents 5,000 characters for Plus, Pro, Enterprise, Business, and Education. Free and Go users can save up to 1,500 characters.
Do changes affect an existing conversation?
OpenAI says setting updates apply immediately across all chats, including existing conversations. That affects subsequent responses. It does not rewrite earlier messages, and previous instruction text may still appear in chat history.
Are custom instructions private when I share a chat link?
OpenAI says they are not shared with shared-link viewers. However, relevant information may be provided to third-party plug-in developers when you use their plug-ins, so avoid sensitive standing context and use only plug-ins you trust.
Should I use all 5,000 characters?
No. Use enough space to state stable, non-conflicting preferences. Keep temporary project details in the current conversation and remove rules that no longer improve typical responses.
A short final checklist
Confirm that your account has the limit you expect. Keep standing preferences separate from current-task details. Write rules that can be checked, remove contradictions, and avoid sensitive information that does not belong in every chat. Review Data Controls and plug-in access before saving account-wide context. Most importantly, revise the instructions when they stop matching the way you actually work.