Every Reddit account has a number attached to it, sitting quietly under the username on any profile. That number is karma, and most people who've spent time on the site have some rough sense of what it means without ever really knowing how it gets calculated. This piece is about closing that gap: what karma actually is, how it accumulates, what it does and doesn't do, and why the exact mechanics stay fuzzy even to people who've studied Reddit closely.
What karma actually is
Karma is a cumulative score tied to your account, not to any individual post or comment. When people say "that post got a lot of karma," what they mean is that the post itself earned a certain amount of score, and that score then gets folded into your running total. The post's own number stays visible next to it, but your account-level karma is the sum of everything you've ever posted or commented, still live on Reddit or not.
Reddit actually splits this into two separate pools: post karma and comment karma. Post karma comes from submissions, links, images, text posts, whatever you've started as a new thread. Comment karma comes specifically from replies inside those threads. Your profile shows both totals separately, and they behave a little differently in practice. Comment karma tends to accumulate more steadily for active users, since a single popular thread can produce dozens of chances to comment, while post karma is more feast-or-famine: one submission either catches on or it doesn't.
There are a few other karma types you might notice on a profile, like award karma from receiving Reddit's gilding system, but post and comment karma are the two that matter for almost everything discussed here.
The mechanic, described honestly
At the simplest level, karma moves up when people upvote your content and down when they downvote it. That's the entire public-facing logic. What happens between an upvote landing and a number changing on your profile is where things get murky, and it's worth being straight about that murkiness instead of pretending otherwise.
Reddit does not publish an exact karma formula. There's no official document laying out "one net upvote equals one karma point, always." In fact, the visible vote count on a post or comment is deliberately fuzzed. Reddit has long obscured precise vote tallies as an anti-spam and anti-manipulation measure, which means the displayed upvote count you see is an approximation, not a raw count straight from the database. Karma totals built on top of those votes inherit some of that same imprecision.
What we can say with confidence: karma generally tracks net upvotes minus downvotes on your contributions, applied roughly and with some obscuring built in. What we can't say, because Reddit hasn't said it: the exact ratio, whether every vote counts equally, whether there are diminishing returns on high-traffic posts, or whether specific subreddit multipliers exist. Anyone who tells you a precise formula, like a claim that comments are worth some exact fraction of a post vote, is guessing or repeating someone else's guess. Treat those numbers as folklore, not documentation.
The same goes for decay. People often assume karma quietly drops over time if an account goes inactive, similar to how a credit score might soften with disuse. There's no officially documented decay mechanism that works this way. Karma can drop if individual posts or comments get downvoted after the fact, or if content gets removed, but there's no confirmed passive decay just from not logging in. If you've heard otherwise, it's speculation that's circulated long enough to sound like fact.
What karma is actually used for
Despite the fuzziness around calculation, karma does real work on the platform. Its main practical function is as a gate. Plenty of subreddits set minimum karma thresholds before you're allowed to post or even comment, and some go further and require a minimum account age on top of that. A moderator of a large subreddit doesn't want a brand-new, zero-karma account showing up to drop links or promotional text, so karma minimums act as a basic filter against throwaway accounts and spam.
Beyond individual subreddit rules, karma functions as a general trust signal, both to human moderators and to Reddit's own automated systems. An account with years of history and a substantial karma total looks less like a bot or a fresh burner account than one created yesterday with a single comment to its name. Automated spam filters take signals like this into account when deciding whether to auto-remove a submission or flag an account for review. None of this is published in granular detail either, since publishing the exact thresholds would make it trivial to game them, but the general shape of it, karma as a proxy for "this account has some history," is well understood.
That's really the ceiling of what karma does. It doesn't unlock special posting privileges beyond what individual subreddits set, it doesn't grant moderator status, and it doesn't change how Reddit's front page algorithm treats your future posts in some cumulative way tied to your lifetime total.
What karma doesn't mean
This is the part worth being blunt about. High karma does not mean someone is right. A comment with thousands of upvotes isn't more factually accurate than one with a dozen, it's just more popular, or posted earlier in a thread, or better timed, or funnier. Karma measures agreement and engagement at a specific moment, not truth or expertise. People conflate these constantly, treating a high-karma comment as some kind of verdict, when really it just reflects what a scroll of people felt like clicking an arrow on.
A related misconception: karma isn't currency. You can't spend it on anything within Reddit itself. It doesn't buy you Reddit Premium, doesn't purchase awards, doesn't get you anything material. Reddit Premium and awards run on Reddit Coins, a completely separate system tied to actual payment, not karma. The two get confused because they're both numbers attached to an account, but they don't interact.
Karma also doesn't affect vote weight. An old account with high karma doesn't get a heavier upvote than a newer account with a few hundred. Every vote counts the same regardless of who's casting it. There's no tiered voting system where veteran accounts carry more weight, whatever intuition might suggest about "senior" users having more pull.
And high karma doesn't automatically make an account more trustworthy in any deep sense. It mostly just means the account is older or has been more active. Plenty of low-effort but well-timed comments rack up karma without reflecting any particular insight or credibility. Karma is a rough, blunt signal, useful for filtering out obvious spam and brand-new throwaways, but a poor substitute for actually reading what someone wrote and judging it on its own merits.
How karma compares to a follower count or a like count
It's worth contrasting karma with the metrics other platforms use, because the differences explain a lot about why Reddit works the way it does socially. A follower count on Instagram or a subscriber count on YouTube is tied to a public identity that people actively choose to follow, and it's visible and comparable in a very direct way: more followers generally reads as more influence, full stop. Karma isn't really built to communicate influence in that same direct sense. It's tied to accumulated voting outcomes across potentially thousands of separate posts and comments, most of which nobody browsing your profile will ever read individually.
A like count on a single piece of content is closer to karma's per-post building block, but even there the comparison breaks down quickly. A single popular Instagram post's like count stays fixed and visible on that post forever, a permanent public record of exactly how that piece of content performed. A Reddit post's vote count is fuzzed, changes over time as votes get recalculated, and eventually the post ages out of relevance entirely even if the number technically still sits there. Karma takes all of that fuzzy, evolving, post-level data and folds it into one account-level running total, which is a very different kind of signal than a clean, stable, per-post number that other platforms show off. That's part of why treating karma as directly comparable to a follower count or like count, when someone is trying to reason about "influence" across platforms, tends to lead to bad conclusions.
Why the fuzziness is by design
It's tempting to want a precise answer here, a clean formula you could point to and say "this is how it works." Reddit's choice not to publish one isn't an oversight. Obscuring exact vote counts and calculation details makes it harder for anyone to reverse-engineer the system and manipulate it at scale. If the formula were public and exact, gaming karma systematically would be far easier, and the karma thresholds subreddits rely on to filter spam would stop meaning much of anything.
That tradeoff, less transparency in exchange for a system that's harder to game, is a reasonable one, even if it leaves outside observers describing the mechanics in general terms rather than exact ones. Anyone claiming otherwise, whether it's an exact point value per upvote or a guaranteed decay schedule, is filling in gaps Reddit has deliberately left unfilled.
If you want to understand how karma specifically breaks down between what you earn from starting threads versus replying inside them, the differences are meaningful enough to cover on their own, in post karma versus comment karma. And if karma mechanics are just one piece of a bigger question, how to actually build a presence on Reddit the right way, the broader Reddit marketing guide covers subreddit selection, timing, and the rest of that picture.