Due to the size restrictions of our shipping methods, your futon may have been rolled, tied and wrapped in plain brown craft paper or carton for shipment to you. Because of this, your futon may appear to be a bit shorter and/or narrower than what you have ordered.
This is normal and it will relax and "grow" in length and width, once it has laid flat and has been used for a day or two (the bigger ones may take a bit longer because they've been "squished" more). You can put the mattress on the frame right away. Open the mattress and leave it in a sofa position for a few days, that will help to break it in the middle. The mattress should open up to about 90% of its size within a few minutes and will stretch to its original size within the next 48 hours.
Remember to flip and turn it regularly. The first month or so, every week is good, and after that, once a month is fine, or as needed. Spot-wash as needed and if possible a day in the sunshine now and then will work wonders for "sun-bleaching" and refreshing your futon/top mattress/cushion.