Calendars are unlike most other small office or paper products that we purchase. As they contain a whole year's worth of dates, you will certainly want your calendar to last at least that long. If you enjoy doing your own custom calendar printing, you may want to look into laminating your finished product to ensure it lasts.
Lamination will protect your custom calendar by protecting it from the elements. If you use your custom calendar at your office, think of the last time you spilled your coffee. Or the last time that a pen bled all over the place. Accidents can turn a custom calendar printing project into a waste of time and paper.
Lamination is cheap and easy. You can purchase laminating kits to go along with your custom calendar printing equipment for a low price. However, uunless you do custom calendar printing on a large scale, you will be best off going to your local print shop with your finished calendar and asking if they can just do it for you.