A 5 mil poly tarp is lightweight and typically used for short-term outdoor protection of goods, such as firewood, hay, and camping gear. It’s also often used as a cover for boats and other watercraft when not in use.

An 8 mil poly tarp is a bit heavier than the 5 mil option and is recommended for temporary outdoor protection from the elements. It’s also great for covering construction materials and equipment, as well as for use as a ground cover.

A 12 mil poly tarp is a popular option for covering large items and for use in construction. Its heavy duty design is great for covering roofs, boat storage, and long-term outdoor protection.

A 16 mil poly tarp is suitable for extreme weather conditions, and is typically used for long-term outdoor protection or as a roofing material. It’s also often used to protect large items, such as vehicles and boats, from the elements.

A 20 mil tarp can be used in almost all conditions.