The size of the laito such as blade length, overall length and barycenter must be set according to the user’s physical condition. The matching of iaitō length, weight, and balance to the practitioner’s build and strength is of utmost importance to safely and correctly perform the iaidō forms (kata). The practitioners whose rank is below 3rd Dan usually use lighter iaito while the practitioners whose rank is higher than 5th Dan can use heavy iaito 1500g because they have licence of tameshigiri.

To pursue a fast pulling speed, the blade and handle of iaito is shorter than standard katana.