HOW IT ISCALCULATED
A rating only means something inside the pool of players it was earned against. The converter puts every pool on one common scale with a single formula, then reads the other pools off that scale.
The formula
Every number on the converter comes from the ASCENDCHESS rating formula, version 2. It is the same formula behind the Est. FIDE rating ASCENDCHESS members see, so the converter and a member's own rating are read off one scale.
It blends several published comparisons of rating systems into one formula of our own, so this page cites no external dataset for it.
How a conversion is made
Your rating is placed on the formula's common scale, which reads like a FIDE rating. Then, for each other pool, the converter finds the lowest rating that the formula places at that point or above it. That rating is the number you see.
One number, no range
Each conversion is one number, labeled an ASCENDCHESS estimate. The formula gives no range, so the page shows none. Players who share a rating in one pool spread out in another, and one number cannot show that spread. Read it as a typical value, not a promise about any one player.
Where it stops
The converter accepts ratings from 100 to 3500. Some conversions still have no answer. When the point on the scale is below or above everything a pool reaches from 100 to 3500, there is nothing to read back, and the page says the rating is outside the range we can estimate. When the formula holds one value flat across a run of ratings in a pool, no single rating matches it, and the page says there is no single number for this rating. Either way it says so instead of making up a number.
Some ratings sit below the bottom of the formula's scale, so there is nothing to convert: USCF Regular up to 180, USCF Quick up to 150 and USCF Blitz up to 120.
In a few places the formula steps up between two neighboring ratings. A point inside the step reads back as the first rating past it, so converting there and back again can land higher than where you started, by as much as 130 points.
The pools
Chess.com and Lichess are converted at each time control, and USCF at Regular, Quick and Blitz. FIDE Standard is the scale itself, so a FIDE rating stays as it is. Bullet ratings convert with the formula's bullet curves, but they never count toward a member's Est. FIDE rating. World Chess uses our Chess.com curves for now, because we have not yet measured how World Chess ratings compare.
Versions
This page describes version 2 of the formula. When the formula changes, its version number changes and this page is updated with it.
To check the formula and later re-fit it, we collect paired ratings from ASCENDCHESS members who connect more than one rating system. Only ratings tied to the member's own account count: a connected Lichess or Chess.com account that synced in the last 30 days, a USCF Regular rating looked up by ID and established, and an official FIDE Standard rating. Ratings typed into a profile, house and test accounts, and anyone we cannot confirm is 18 or older are left out. The data is kept only as groups of at least 50 members, never as one member's ratings, and it is not shown on the converter or used in any number yet.
Limits worth knowing
- The formula was built from published comparisons and has not yet been checked against our own members' ratings.
- Ratings drift. A pool's average moves as players join and leave, so a conversion can age.
- Fast time controls convert less reliably than slow ones, and the extremes of any pool have the fewest players.
- A conversion is a starting point for setting goals or picking an event, not a prediction for one player.