Christmas Tree Light Calculator

This calculator sizes the lights for a Christmas tree two ways. The first uses the trade rule of about 100 bulbs for every foot of height, adjustable from a light scattering to a show tree. The second works from the shape: give it the height, the width at the base and how far apart the wraps go, and it adds up the circumference of every turn of the spiral to get the strand length. Both return the number of strands to buy, the total lit length, the watts and amps, and how many trees a 15 amp circuit will carry. Bulb wattages are typical figures, so size a circuit from the tag on the strand rather than from this page.

Calculator Type
Units

The trade rule: about 100 lights for every foot of height, which is about 330 a metre, more or less depending on how lit you want it.

The lit length printed on the box. A 100 count mini strand is usually 20 to 25 ft.
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Units

Work it out from the shape: height, width at the bottom, and how far apart the wraps go.

The diameter across the widest branches, not the radius.
How far the spiral climbs on each turn. Six inches is a common working figure, and four inches is a dense wrap.
The lit length printed on the box. A 100 count mini strand is usually 20 to 25 ft.
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