The Foam Factory – foam inserts- https://www.thefoamfactory.com/seatcushion/diy_measure.html
New foam inserts are available for all types of cushions. In a house or an RV, you might have chair cushions. Foam cushions are standard on most boats. Any type of foam that is frequently used or exposed to wind and water will wear out faster. When the foam inserts begin to break down or emit a weird odor, replace them. Foam that is breaking down can be a hazard. Bacteria may grow.
If the cushions have gone rotten, you can usually tell. They’ll lose their tenacity. A small amount of foam may leak out of the cushion at times. If you’re unsure, it’s preferable to replace them right away. This is not pricey and it’s the best course of action. You don’t want to expose your family to foreign bacteria that hides in old pillows.
The first step is to take diagonal and horizontal measurements of the cushion. You must also determine the cushion’s depth. Due to the fact that it is older and the foam has broken down, it may not be as thick as it once was.
It’s preferable to purchase foam inserts that are slightly larger than the cover than to purchase cushions that are too small and will not fit properly. One advantage of foam inserts is that they are relatively easy to cut. You can purchase a larger piece of foam and cut it to the size you require. Or you can choose to have the store cut it for you.
Websites like The Foam Factory have every type of foam at cheap prices. They’ll cut your foam to any shape or size. Their customer service people will help you if you’re having a hard time with the sizes or type of foam to purchase.