A Steam achievement's global percentage is the share of players who have unlocked it. Valve describes it as "the percentage of people that have unlocked this achievement," but doesn't say exactly who counts as one of those people. The numbers show the base is wide: even achievements you earn in a game's first minutes rarely pass 75-87%, because many counted players barely play. Steam labels an achievement rare when fewer than 10% of players have it.
What a Steam achievement percentage means
The percentage next to an achievement is how many of a game's players have unlocked it, out of 100. Valve's ISteamUserStats documentation says the value is "the percentage of people that have unlocked this achievement from 0 to 100," and describes the data as "the percentage of players who have received each achievement for the current game globally."
It's the same number everywhere Steam shows it: on the game's achievements page, in your library
and in profile showcases such as Rarest Achievements. Steam's public Web API endpoint
GetGlobalAchievementPercentagesForApp serves it too, keyed only by the game's app ID, so no
account or API key is needed to read it. The API returns each value as text with one decimal
place, such as "74.0", which is why you never see a percentage finer than 0.1%.
How Steam calculates achievement percentages
Valve publishes the formula's top half, not its bottom. The top is simple: players who have unlocked the achievement. Who counts as a player for the bottom half isn't documented anywhere Valve publishes.
The data narrows it down. Look at each game's most common achievement, the one nearly everyone who plays should get, in Steam's global stats on October 29, 2026:
| Game | Most common achievement | What it takes | Global % |
|---|---|---|---|
| Terraria | Timber!! | Chop down your first tree | 87.0% |
| Hades | Escaped Tartarus | Clear the first region | 81.8% |
| Portal 2 | Wake Up Call | Survive the manual override, minutes into the story | 74.0% |
| Team Fortress 2 | Race for the Pennant | Run 25 kilometers | 49.5% |
If the denominator only included people who had really played, chopping a tree in Terraria would be close to 100%. Instead, 13% of counted players never did. So the base includes a lot of people who own a game and never got past the opening, or never launched it at all. That's why every percentage is lower than it "feels" from inside the community of people who actually play.
Why Steam achievement percentages are so low
Most low percentages come from who's counted, not just from difficulty:
- People who never really played. As the table above shows, a big share of counted players never get past the opening. Games bought in bundles or sales, claimed for free or left in the backlog are the likely reason.
- Free-to-play games. A free game is easy to try and drop, so the base is huge. Team Fortress 2's most common achievement sits under 50%.
- Long or grindy goals. Endgame and completion achievements naturally land in single digits: Portal 2's hardest co-op achievement is at 2.4%, and Terraria's rarest at 0.5%.
- Achievements added later. An achievement added in an update or DLC starts at 0% for everyone, including players who stopped playing before it existed.
The Achievement Sets beta changes how DLC and seasonal achievements are grouped, but Valve's announcement doesn't say whether a DLC set's percentages are measured against DLC owners or all players. Our Achievement Sets explainer covers what the beta does change.
What counts as a rare achievement on Steam?
Steam marks an achievement as rare when fewer than 10% of players have unlocked it. Valve doesn't publish this cut-off, so we checked it: the new achievements page shows a "rare" count for each game, and we compared it with the raw percentages from Steam's API on October 29, 2026.
| Game | Achievements | Steam's "rare" count | Below 10% in the API |
|---|---|---|---|
| Terraria | 137 | 33 | 33 |
| Portal 2 | 51 | 22 | 22 |
| Hades | 49 | 10 | 10 |
| Team Fortress 2 | 516 shown | 263 | 262, plus 5 at exactly 10.0% |
The first three match exactly. Team Fortress 2 is off by one, and five of its achievements sit at exactly 10.0%. The API rounds to one decimal, so one of those is most likely just under 10% in Steam's own data.
Rare achievements get special treatment in the Steam client. They have their own animation: Valve's June 2023 client update "fixed missing animation for rare achievements on the game details page." Your profile's Rarest Achievements showcase ranks your achievements by these same percentages.
Where to see global achievement stats
Open any game's achievements page on the Steam Community, or from the game in your Steam library, and switch on Show Global Stats. Valve's Achievement Sets announcement says "Global Stats, or the per-achievement completion rates, are now available as a toggle here rather than on a separate page." The page is public, so you can check a game's percentages without owning it or signing in.
What this means for Steam Game Idler
Steam Game Idler shows the same global percentages Steam does, and uses them in two places:
- Achievement Manager shows every achievement's global unlock percentage and can sort by Global unlock %. It also adds a rarity label from Common to Legendary. Those labels are Steam Game Idler's own bands (Rare means 5-15%, Epic 1-5% and Legendary under 1%), so they don't line up with Steam's single under-10% "rare" label.
- Achievement Unlocker unlocks a game's achievements in order of global rarity by default, starting with the most common. You can change that with Custom Order & Unlock Delay.
With Steam Sign-in, the Steam session itself doesn't provide these percentages, so Steam Game
Idler reads them from the same public GetGlobalAchievementPercentagesForApp endpoint described
above. With Local Sign-in, the local Steam client provides them. Either way, the numbers match
what Steam shows.
Download Steam Game Idler to see a game's rarity at a glance.
FAQ
How are Steam achievement percentages calculated?
Steam divides the number of players who have unlocked an achievement by the number of players it counts for that game, and shows the result to one decimal place. Valve doesn't publish exactly who it counts, but the data shows it includes many people who barely played.
Why are Steam achievement percentages so low?
Because the base includes everyone counted as a player, including people who bought a game and never got far. Even achievements earned in the first minutes of Terraria, Hades or Portal 2 sit between 74% and 87%.
What percentage is a rare achievement on Steam?
Under 10%. Steam's achievements page counts an achievement as rare when fewer than 10% of players have unlocked it, which matched Steam's API data for every game we checked.
Where can I see global achievement percentages?
On a game's achievements page on the Steam Community or in your library. Switch on Show Global Stats to see each achievement's percentage. The page is public, so you don't need to own the game.
Do Steam achievement percentages change?
Yes. They're calculated from all players, so they move as new players arrive and existing players unlock more. A new game's percentages can shift a lot in its first weeks.
Do DLC achievements count toward the percentage?
DLC achievements have their own percentages like any other. Valve hasn't said whether they're measured against DLC owners or all of the game's players, so a low DLC percentage may partly reflect how few people bought the DLC.
Sources
- Valve, Steamworks Documentation: ISteamUserStats, accessed October 29, 2026.
- Valve, Steam Achievement Sets Now in Beta, October 15, 2026.
- Valve, Steam Client Update - June 14th, June 15, 2023.
- Steam Web API,
ISteamUserStats/GetGlobalAchievementPercentagesForAppandGetSchemaForGamefor Terraria, Hades, Portal 2 and Team Fortress 2, accessed October 29, 2026. - Steam Community, achievements pages for Terraria, Hades, Portal 2 and Team Fortress 2, accessed October 29, 2026.
- Achievements
Creator and maintainer of Steam Game Idler.
