Experts suggest that a good rule of thumb is to replace your mattress every seven years. In seven years, the mattress will most likely not be providing you the most comfort and support.
If you're older than 40, it may be wise to get a new mattress every five to seven years because our bodies are more susceptible to pressure as we get older.
When shopping for a mattress, it is suggested that you lie down for a full 15 minutes in your typical sleeping position, if you're able to experience the mattress in person. Experts found that shoppers who have liked the mattress after testing it for 15 minutes enjoyed the mattress the same after a month's time.