The Length of a Spiral Christmas Garland calculator computes the length of a Christmas Garland or Christmas Lights needed to wind around an object (e.g. railing). This is based on the length covered, spacing between spirals and the diameter of the spirals.
INSTRUCTIONS: Choose units and enter the following:
- (H) Length of Wound Garland
- (P) Distance between Spirals
- (D) Diameter of Garland Spirals
Length of Garland (L): The calculator returns the length of the garland in feet. However this can be automatically converted to compatible units via the pull-down menu. 
Christmas Decorating
Decorating for Christmas is fun and makes your home feel extra special. A garland of evergreen wrapped around a staircase banister or guardrail is a nice touch and a great place to hang Christmas ornaments. BUT, how long of a garland do you need to wrap your railing? It's just some useful math. This calculator will tell you how long your garland needs to be.
Thanks to Kelly and Sean McDonagh for recommending this calculator and providing the photo from their house! Sean also pointed out that this also works for Christmas lights!!!
The Math / Science
A spiral is a helix. The Christmas garland wrapped around a pole or circular rail forms a helix.
The formula for the length of a helix is:
`L = H/P * sqrt( (pi*D)^2 + P^2)`
where:
- L = Length of Helix
- H = Height of Helix
- P = Pitch of Helix
- D = Diameter of Helix
Note: The number of turns (n) is equal to (H/P)