What is the Unified Rankings?

It is an attempt to create a consisten ranking list, going as far back as possible (currently starting in January 1990). It is not meant to be a replacement or correction of any of the existing BWF/IBF ranking lists, rather an example of how a uniform ranking list for the last 30 years could potentially have looked. It is also experimental, and subject to changes and adjustments.

How is that achieved?

All tournaments have been categorized according to the current (2018-2021) ranking regulations and the points have been (re)calculated according to those categories

What's the difference?

For tournaments post-2018 there is no difference. For tournaments pre-2018, there will be some difference, as the amount of points awarded in each tournament may differ compared to the official ranking lists. Before 2009 there is of course no official BWF ranking list, but the Unified Rankings are still calculated in exactly the same way. The only slight difference is that for calculating the rankings of the players only the 8 best results are used (compared to the 10 used in the current official rankings). This is to compensate for the fact that players usually played much fewer tournaments before 2009.