https://swimstandards.com/imx will calculate IMX (and IMR) scores for any swimmer. It will also display the times on the swimmer's individual page as well
Here are some copy/pastes from the meet announcement to clear up some of the verbiage:
The qualifying period for this event is September 1, 2021 through the entry deadline.
All times MUST be achieved in one season and in one course. Times from the 2021-22 season shall not
be combined with times from the 2022-23 season.
All athletes that are 9-14 years on the first day of the meet are eligible for the meet if they have achieved the
minimum qualifying score in any age during the qualifying period.
The qualifying standard will be a minimum IMX Challenge score of 1,800 points for all ages and genders
Age of the athlete will be the first day of the competition.
Any swimmer that is 9-14 year-old is eligible for the meet who has achieved the minimum qualifying
score in any age during the qualifying period. That is, a swimmer who has achieved a minimum
qualifying score as a 10-year-old and ages up to 11 prior to the start of the meet will be eligible to enter
the meet and compete as an 11-year-old. A 12-year-old who has achieved the minimum qualifying
score but ages up to 13 prior to the start of the meet will be eligible to enter the meet and compete as a
13-year-old (even if he/she has not swum all the required events as a 13 yr old).
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