Deck Railing Calculator

Learn More About Deck Railing

If your deck ranges between 24 inches and 30 inches from the ground, local building safety codes require your deck to have a railing that is at least 3 feet (36 inches) high, extending from the deck’s surface to the top of the railing. Although this is a general rule, it’s best to check with your local building codes when securing a permit to build your deck to be sure your deck is up to code. However, if your deck is near a steep drop off, embankment, or cliff, you should include a railing for safety purposes.

Your deck will require a railing that extends on both sides of your stairs, and around the perimeter of your deck. This railing will require balusters (sometimes called spindles) and vertical posts that support your railing. These posts act as anchors to the railing and tie the deck frame and railing together. Use this deck railing and spindle calculator to help you find out how many balusters (or spindles) you’ll need for your project.

How Many Spindles Do I Need?

In order to determine how many spindles you’ll need, you should first know how much space should be between deck balusters. In order to comply with building regulations and codes, balusters must be spaced less than 4 inches apart. The test is called a “4-inch sphere test” - basically could a 4” wide ball fit between the balusters. If not, you should be compliant.

How Far Apart Should Spindles Be On a Deck Railing?

The general rule is that your railing must have three balusters per foot (every 12 inches), although you can place them closer together if you’d like. The length of your railing (in total linear feet) will play a factor in how many balusters you’ll need to be sure your deck and railing are compliant with safety standards. Use this deck railing and spindle calculator to help you find out how many balusters (or spindles) you’ll need for your project.