Search for wrinkles in the carpet. Wrinkles can occur anywhere in the carpet, but are often found in the center of the room. Wrinkles can vary in size, and their presence indicates your carpet needs to be stretched.
Scan the carpet for lumps or bulges. Lumps and bulges are not only unsightly, but can be dangerous as well, as they create tripping hazards. They can appear anywhere in the carpet. Stretching will get rid of most lumps and bulges in your carpet.
Look for loose carpeting, which will often move when you walk on it. You may be able to grab loose carpeting and pull it away from the floor. If you find loose carpeting, your carpet needs to be stretched.