Reddit's own guidance says that if more than one in ten of your contributions promotes your own thing, you are probably a spammer. Moderators use the rule loosely as a smell test rather than arithmetic, but the smell test is quick and it is the first thing they run on a profile that mentions a product.
How a moderator counts
They open your profile, sort by new, and scroll. They are looking for three things: how many comments mention a product or link, whether those are concentrated in the last few days, and whether the non-promotional comments are real contributions or one-line filler padding the ratio.
That last point matters. Ten "great post!" comments and one link is not 90/10; it is a spammer who has read about the rule.
What counts as promotion
Anything that points at what you sell: a link to your site, naming the product, a "DM me" invitation, a comment on a competitor thread that steers toward you. A disclosed, useful reply that names your tool once still counts as promotion; disclosure makes it honest, not neutral.
What does not count: answering the question fully with no product in it, even in a thread about your category. That is the 90.
Keeping the ratio without a spreadsheet
Three practical rules cover it:
- Never mention the product in a subreddit until you have been useful there several times.
- Treat a mention as spending something. After each one, the next several contributions are product-free.
- Count per account, not per subreddit. Moderators see the whole profile.
If you use software to draft replies, make sure it holds the ratio at publish time, not draft time. A tool that writes a promotional draft and lets a person approve it has not enforced anything; the ratio has to be checked when the comment goes out, against what has actually been posted.
What tips a reasonable account into trouble
Usually a launch. Founders behave for a month, then launch, and post about it in six subreddits in a day. The ratio collapses and the reports follow. Spread launch mentions over two weeks and keep contributing in between.
The honest summary
The rule is not a quota to fill. Promotion is the exception you earn by being the most useful person in the thread the other nine times.