Sailonet disposes of a data base with over 7000 boats. Despite this we recommend to measure again for every sail. This allows to verify if your rig corresponds well to the initial set up and also confirms (or not) the measures in our data base.
For two identical boats the measures can deviate, depending on the mounting of used systems (furling systems, sail battens, etc.)
It’s always better to measure straight on the rig. Sometimes it’s also possible to take the previous sail as reference.