Covering cakes with fondant gives you a flawless, satiny finish that can be further decorated. While fondant is a common fixture on wedding cakes, it is also becoming more popular on special occasion cakes and even cupcakes. Fondant doesn't have a long shelf life, especially after the package has been opened, so, it’s important to buy just enough to cover and decorate your cake so there aren't many leftovers that go to waste. To purchase the correct amount, you'll need to measure before you cover and while you cover your cakes.

Determine how many tiers your cake will have, their shape, and the size of those tiers. You’ll need to measure the diameter of your cake, how tall each tier will be, and the number of tiers. For example, you might have a two-tier round cake with one tier that is 6 inches wide and 3 inches tall, and a bottom tier that is 8 inches wide and 3 inches tall. Write down your measurements.

Use a fondant chart to determine how much fondant you will need. Because fondant is sold in pounds or ounces, you will need to know how many pounds or ounces are required based on the size of your cake. You can find fondant charts online on sites like Wilton.com and Baking911.com or by visiting the fondant manufacturer’s website, like Fondarific.com or SatinIce.com. For example, using the measurements above, you would need approximately 14 ounces for your 6-inch tier and 18 ounces for your 8-inch tier -- making a total of 2 pounds of fondant. Note you will need more fondant for square or odd-shaped cakes than round cakes.

Consider your skill level with fondant. If you’re new to decorating cakes, add an additional pound to compensate for any fondant that might get ruined while you’re practicing covering your cakes. If you’re going to make fondant decorations, add an additional half pound or full pound to your measurement.

Cut, fill and assemble your cakes. Cover the cake or cakes with a thin layer of buttercream for the fondant to adhere to. Once the cakes are assembled, use your tape measure to measure each tier being covered again. Measure the diameter of the cake and how tall the cake is and write it down. For multitiered cakes, you must measure each tier individually.

Multiply the cake’s height by two and add that total to the diameter of the cake. Then, add an additional 1 to 4 inches to that total based on your experience. If you’re new to using fondant, add the full 4 inches, but if you’re experienced, just add 1 to 2 inches. Your final amount is the total diameter of rolled fondant you’ll need to cover your cake.

Roll out your fondant to a ¼ or 1/8-inch thickness until it reaches your desired diameter on all four sides. Measure the rolled fondant’s diameter before placing it on your cake.