UK ILR requires you to be absent from the UK for no more than 180 days in ANY 12-month rolling period in the 5 years prior to application. After entering your trips, this tool presents the relevant period visually, showing the absent days in each 12-month rolling period.
It also states whether you pass or fail for the whole period in question, and if you fail, tells you exactly which periods you failed and your absent days in each.