A player’s rating changes by graded amounts depending upon the rating difference between his/her rating and the
rating of his/her opponent.

The following tables define the calculations:

The winners rating is increased by the amount in the above table (adjusted by the weighting factor below)
while the losers rating is decreased by the amount in the above table.

For main events, the above weightings shall be applied only to the winners points, the losers points are not adjusted by a weighting factor. For division and consolation events the weighting applied to the winners points shall be half the tournament weighting, the losers points shall be similarly weighted up to a maximum of 1.

To qualify as a National Open, the event must be Open to players of any country, and the event must be advertised in all readily available OTTF lists of tournament dates.

Players are assigned a rating as soon as they compete in a qualifying event.

Players are assigned an initial rating based upon their initial results. This may be reviewed at any time when further results are received.

Players only have one rating and so appear on any list where appropriate with the same rating points.

All results of singles matches are processed.

Players will appear on Rating Lists until 24 months has expired since their last qualifying match played.

Players not listed (due to lack of participation), shall retain their rating, and this shall be used to determine seedings, grade eligibility etc.

Players who have not played in any rated match for an entire calendar year, shall have their rating depreciated at a rate of 2% at the end of each such year.