I noticed that I can only perform certain actions such as commenting a finite number of times in a given period of time. Obviously, rate limiting is in place to prevent accidental misuse or intentional abuse of certain features.

Where else is rate limiting applied on Stack Exchange sites, and what are the limits?

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Rate Limit Rationale

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  • Undisclosed limit, applies to IP addresses
    • Applies to the entire network; if one makes too many requests on one or more sites, access to all network sites is restricted
    • Does not apply to non-load-balanced services not served from the same network as public Q&A (chat, the API, etc.)
    • Should not be triggered during normal browsing; if you get it, it either means you're sharing your IP with multiple users accessing the network, or your browser or an extension is hitting the site with one or more extra requests every time you load a page

Too many requests: This IP address has performed an unusual high number of requests and has been temporarily rate limited.


  • Voting & Flagging

    • Same amount of comment flags as one does post flags (default 10, may rise up to 100 based on flagging activity or reputation; see Flagging below)

      • Comment flag and post flag allowances are separate
    • 30 comment upvotes per day (automatic upvotes resulting from close votes do not count)

    • no minimum wait time between votes

      Comment voting - Daily vote limit reached; vote again in 3 hours

    • Can only flag one comment every 5 seconds

  • Deleting (treated like voting)

    • No limit per second (previous one-comment-per-5-second limit removed)
    • Can only delete own upvoted comments under 20 posts per day (multiple comments under same post are treated as one) You have already deleted your own comments from 20 posts today; further deletes are blocked
  • Creating

    Comment creation - You may add another comment in 24 seconds

  • Editing

    • comment can be edited every 5 seconds by its author or a diamond mod Comment editing - You may only edit a comment every 5 seconds
    • comments cannot be edited after 5 minutes (except by diamond moderators)



  • Users with < 125 rep on the current site, 40 minutes since their last question anywhere on the network (This applies to the user's IP address, not their account. If the user shares that IP with other users, they can be limited by the other user asking a question anywhere on the network; similarly, if the same user posts a question from a different IP address, they may not be limited.)

    Question limit - You can only post once every 40 minutes

    • Other per-site limits may apply; e.g. on Stack Overflow, new users can only ask once every 90 minutes. Some of these per-site limits do also check the account, not just the IP address.
    • While the limit is waived for users with 125+ reputation on a given site, questions posted on sites where one has 125+ reputation still count toward the rate limit for sites where one doesn't. For instance, if you ask a question on a site where you have 150 rep, you can't ask another question on a site where you have only 100 rep for the next 40 minutes; however, you can ask them in reverse order immediately (first on the 100-rep site, then on the 150-rep site).
  • Users limited by Anti-Recidivism System, one question per week

  • Users limited from asking questions for 1 – 7 days based on the performance of their previous questions

  • Users prevented from asking questions due to the quality filter: one question per 6 months

  • Users with < 10k rep trip CAPTCHA* if more than once per 60 seconds, or within 5 seconds of starting new post

  • Users with ≥ 10k rep trip CAPTCHA* if more than once per 30 seconds, or within 5 seconds of starting new post

  • On Stack Overflow, Super User, Server Fault and Mathematics (not active on all other sites)

    Sorry, you are only allowed to ask 50 questions in a 30 day period

  • Stack Exchange staff members are not subject to these rate limits on meta sites


  • Users with < 125 rep must wait 3 minutes between answers

  • Users with between 125 and 10k rep trip CAPTCHA* if more than once per 60 seconds, or within 5 seconds of starting new post

  • Users with ≥ 10k rep trip CAPTCHA* if more than once per 30 seconds, or within 5 seconds of starting new post

  • Users of any reputation level can only answer the same question once every 60 seconds

  • Users with the "staff" bit (i.e. Stack Exchange employees) are not subject to the above limits on meta sites

  • Maximum of 30000 characters for the Markdown source of answer.

    Body is limited to 30000 characters; you entered 30064



  • Edit at most 10 of one's own posts per day (can be modified per site, but no site has modified it)

    • Additional edits to the same post aren't counted
    • Edits to posts created on the same or previous UTC calendar day don't count
    • Edits made to posts scoring -1 or lower don't count
    • Edits to deleted posts don't count
    • Once the limit is hit, no more edits can be made to any of one's own posts, even if the edit would be exempt per the above criteria
    • Does not apply to ♦ moderators, users with the moderator tools privilege ("10k+" users), or Stack Exchange staff members
    • Rollbacks aren't considered edits for any of the above checks

    You have already edited 10 of your own posts today; further edits are not allowed until tomorrow

    (Source: What exactly is the rate limit for editing your own posts?)

  • At most 5 pending suggested edits per editor (20 on beta sites)

    • Limit is partially waived if submitting a tag wiki and excerpt suggested edit at the same time (which counts as two edits) - if the user only has space for one more pending edit, both edits will still be allowed, but they cannot submit another suggested edit until two of their pending edits are approved (i.e. they're no longer exceeding the limit)
  • Unregistered users can't suggest edits on posts < 10 minutes old

  • Users with < 10k rep trip CAPTCHA* if more than once per 30 seconds, or faster than 5 seconds after starting edit

  • Users with ≥ 10k rep trip CAPTCHA* if more than once per 10 seconds, or faster than 5 seconds after starting edit

  • You can only save a tag wiki edit once every 30 seconds, or once every 10 seconds if you have enough reputation (20k/4k on beta sites) to bypass the review queue. (Submitting a tag wiki edit along with a tag wiki excerpt edit at the same time for the same tag is not limited.)

* For all of the above thresholds for hitting CAPTCHA, if you have at least 200 reputation and have solved a CAPTCHA in the last 5 minutes, you will not have to solve one again.


  • 10 flags per day by default

    • 1 bonus daily flag for every 10 net helpful flags in the user's flagging history (helpful minus declined, excluding other types such as disputed and aged away)
    • 1 bonus daily flag for every 2,000 reputation earned
    • A net negative helpful flag count can reduce a user's daily flag allowance to below 10
    • The number of daily flags is hard-capped at 100
  • 5 seconds between flags

  • 3 seconds between opening the flag dialog

    You can only flag for moderator attention 48 times a day

    You may only flag a post every 5 seconds

    You may only load the flag dialog every 3 seconds

  • You can be banned from flagging when too many flags have been declined in a 7 day period; such a ban will automatically be lifted once the criteria no longer apply (after at most 7 days).


  • 20 reviews per queue per day if the queue size is less than 1000 (150 on Stack Overflow)
  • 40 reviews per queue per day if the queue size is 1000 or more (150 on Stack Overflow)
  • Reviews on suggested edits to your own posts do count toward the limit if you haven't reached it yet, but will be allowed through even if you have.
  • No review limit for ♦ mods

Thank you for reviewing 20 Close Votes today; come back tomorrow to continue reviewing.


  • 1 second between two messages, here's the true throttle curve

Chat Throttle Curve

  • There is a similar throttle for starring (details unknown)
  • There is a similar throttle for searching (details unknown)
  • Star limit is 20 stars per room, per day for each user.
  • 30 seconds between creating chat bookmarks

You can perform this action again in 21 seconds


  • 30 votes per day +10 for questions only (question-only votes can't be used once you've cast 25 votes on answers) (source)
    • To further elaborate: you get 10 Q-votes and 30 QA-votes per day. When you vote on a question, you'll use a Q-vote, and on an answer, you'll use a QA-vote. If you run out of Q-votes, you can continue voting on questions, but you'll be using QA-votes. However, once you have only 5 QA-votes left, you'll be blocked from using your Q-votes and all of your remaining voting for the day will use your QA-votes.
  • If one of the posts you vote on gets deleted the same day as you vote, your limit is recalculated as if you never cast that vote (i.e. in most cases, you can cast one more vote, but if you now have more than 5 unused QA-votes, your Q-votes will be unblocked, allowing you to vote more times).
  • If you vote and undo your vote 30 times, your vote gets locked in.

You have voted and undone your vote too many times. Your vote is now locked in

Logging in

  • 3 failed attempts within a minute before a CAPTCHA is displayed

Changing usernames

  • Last username change must be less than 15 minutes or more than 30 days ago. Does not apply to ♦ mods or accounts that are less than 2 days old.

Showing Upvote/Downvote totals

You may only fetch vote counts once every second

Expanding revision history from user activity

  • once per second

    You may only load 1 revision every second


  • Can open close dialog once per 3 seconds
  • 50 close/reopen votes/day/user on Stack Overflow, Mathematics, Server Fault, Super User and Ask Ubuntu, 12 on Stack Apps, 24 on others. Source

You may only load the close dialog every 3 seconds


  • Can only delete 5 of your own posts per day
    • Undeleting and re-deleting the same post on the same day won't count
    • Posts that were made on the same UTC calendar day or the previous UTC calendar day don't count
    • Posts that score -1 or lower don't count
    • Once the limit is reached, no more posts can be deleted, even if they'd be exempt per the above bullets
    • Doesn't apply to diamond moderators
  • 5 delete votes (at 10k) with an extra delete vote for every 1k rep above 10k, max of 30, per day
    • When a 10k+ user with delete votes remaining deletes one of their own posts, that deletion will deduct 1 from their delete votes for the day.
    • Other than that, the counts between self-deleted posts and delete votes for others' posts are kept separate: the number of self-deleted posts is limited to 5 per the above criteria, and if you've used all your delete votes but have not hit the above limit, you can still delete your own posts up until the limit (the counter will show as negative).
  • Question must be closed in order to be able to vote to delete it
  • A question can't be voted to delete until 2 days after closure, unless 20k+ and question score -3 or lower
  • Can only cast one delete vote and one undelete vote on the same post, except when you are the post owner or a moderator.

Destroying accounts

  • Moderators can destroy only one account every 5 seconds.

Winter Bash hats

  • Change hat once every 10 seconds

You may only change your hat once every 10 seconds

iOS and Android apps (deprecated)

  • Due to depending on the API, one second between actions
    First line: "Error". Second line: "You cannot perform this action for another 1 seconds". Third line: "OK"

  • Unlike the normal API, which restricts users to 10,000 queries per day, the apps are allowed a (theoretically) unlimited number of queries per day (restricted to 2^31 - 1 or 2,147,483,647, or the maximum number for a 32-bit signed integer).

    • Note that this is likely to change given that app-specific API features are gradually being retired due to the discontinuation of the apps.

Stack Exchange API

  • Maximum of 300 queries per day per IP address, if not using a dedicated API key

  • Maximum of 10,000 queries per day per key and IP address pair, if using a dedicated API key, with some exceptions:

    • Some high-profile tools that actively help out with the Stack Exchange network receive special keys that grant them an extended limit (e.g. SmokeDetector has a limit of 20,000)
    • The above noted exemption for the mobile apps, which have special keys that don't have daily API limits (see above section for more details)
  • Maximum of one action-performing query per second

  • Occasionally, queries can return a backoff value, to indicate how much time a given application needs to wait before it can perform another query. This value depends on the number and speed of the queries and can change based on various other factors, and as such it's too complicated to fully list here.

  • 3
    How are rate limits for non-humans implemented? Is a count of searches within a short period of time (lets say 5 seconds) calculated each time someone does a search?
    – user784637
    Feb 19 '13 at 8:41
  • 23
    Why are there even limits on the diamond mods?
    – Undo
    May 31 '13 at 15:52
  • @LanceRoberts What does "timer resets" mean, Sir? Mar 9 '14 at 13:08
  • 4
    @AveMaleficum, when you vote on a comment, a timer starts. Everytime you click on the vote or flag button instead of having a smaller amount of time left, the timer resets itself. So you end up trying to time things in your head waiting for it to expire, see here. Mar 9 '14 at 16:00
  • 2
    There's also a limit for page requests per IP address per time period which I think must have recently been tightened (saw it twice yesterday) but I don't know what the exact limit is. Mar 9 '14 at 17:44
  • 1
    Shouldn't per IP throttling occur only for anonymous users? IMO all API calls within the page should have a token associated with them and be throttled per user.
    – paulkon
    Mar 20 '14 at 17:21
  • 1
    What is the point of throttling per action with respect to DoS as opposed to global rate-limiting?
    – paulkon
    Mar 20 '14 at 17:36
  • 7
    ...yay, another 1 secondS. Why is it so hard to not fix all of these once and for all?
    – Werner
    Mar 30 '14 at 14:08
  • @Werner You linked to the tweet that answers your question. Mar 30 '14 at 21:07
  • 3
    @michaelb958: Sadly it doesn't answer it. It just gives Jeff's opinion about these things. There are so many quantifiers on this website and I wonder why nobody ever takes to time to consider the singular/plural issue from the start... It seems as simple as writing a function where you pass it the quantity and it will return either an "s" or nothing and append that to the quantifier. It seems so fundamentally straight-forward.
    – Werner
    Mar 31 '14 at 0:58
  • 3
    @Werner Jeff was the original CTO, and the pluralisation code was written under his watch (if not by him), so his opinion carries a little more weight. The current team could fix them now if it justified the resources, and if they weren't scared of the giant S. (They might be fixing them right now, and they just haven't told us yet so Jeff doesn't find out until that security upgrade's done.) Mar 31 '14 at 1:10
  • 3
    @LanceRoberts How should the chat throttle chart be interpreted? What's the data used to generate it?
    – Stijn
    Jul 28 '14 at 9:27
  • @Shadow, any reference on the comment rate-limit changes? Mar 11 '15 at 14:24
  • @Lance trial and error following this bug report - asked the dev for confirmation. Mar 11 '15 at 15:01
  • 1
    @bad_coder What you wrote here is that editing other people's posts is limited based on reputation. The answer you linked, answer to: How many edits can a high-rep user have?, explicitly states there's no limit to editing other people's posts, but that there is a limit to editing your own posts.
    – Makyen
    Sep 14 at 4:55

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