Non marking shoes are basically shoes that have soles that won’t leave a mark, especially in the gym or any hardwood type floors. Any of these shoes should be fine.
Any indoor shoes made for physical activities or even casual shoes should be fine. Typically, various shoes such as boots or dress shoes with black soles might leave marks on the floor if you slide the side of the shoe on the floor’s surface. Many schools will require non marking shoes mainly to keep their floors from getting dirty.
You can usually check to see if your current shoes will leave marks by rubbing the sole on your bathroom or kitchen floor as if you’re trying to write something with your shoes. Shoes with white soles should also be fine.
Here are a few ways to see if your current shoes have non marking soles:
Flip the shoe over so the sole is facing up. Press your thumbnail or fingernail into the sole and observe if the sole is dented from the pressure. If the sole is dented momentarily, the sole is considered soft and is likely a nonmarking shoe.
Hold the shoe in your hand, with the sole facing down. Place a piece of clean white paper on a hard surface, such as the floor. Rub the sole of the shoe against the white piece of paper with force but do not tear the paper. Look for a scuff mark on the paper. If you see a scuff mark, you do not have nonmarking shoes.
Write with the heel of the shoe at the sole on another piece of plain white paper. Draw a line with the heel on the paper and examine the paper for a marking. If you do not see a mark, you have nonmarking soles. Although shoes with black soles are more likely to leave marks that those with light soles, nonmarking black-soled shoes are available.