Cartoon of man measuring Christmas Tree


We offer some insight for your tree and other common uses for our lights.

This is a complex question and the answer depends largely on personal taste. Here are some tips that may help you decide how many lights you will need.

For Trees: These formulas for determining how many lights you need on your tree are a good place to start. (Measurements in ft.) 

  • For low density: Height of Tree x Diameter of Tree at Base x 4
  • For medium density: Height of Tree x Diameter of Tree at Base x 5
  • For high density: Height of Tree x Diameter of Tree at Base x 6

Christmas tree light density

For Windows, Railings, and Rooflines:

  • Calculate the linear feet of string you will need by measuring along each surface you intend to decorate
  • Tru-Tone Light Strings all have 12” spacing, so the number of bulbs you need is equal to the measured distance in feet.
  • Tru-Tone Light Strings have a decorative vintage style and are intended for use where they can be seen and appreciated. For longer runs and lights that will be seen from a distance such as rooflines and large outdoor trees, we recommend using standard, widely-available paired-wire light strings that come in a variety of lengths and spacing, and can even be purchased on bulk spools. The fewer connection points you have, the less likely you are to encounter problems with poor connections, precipitation issues or shorting.

Illustration of Christmas light string

  • 12” spacing is most common for linear installations. With tighter spacing, the individual bulbs begin to lose some of their individuality, creating more of a solid line effect rather than individual points.
  • For spacing other than 12”, (such as 6” or 18”) simply convert your measured distance in feet to inches by multiplying by 12, then divide that number by the length of spacing to determine how many bulbs you will need.
  • Tru-Tone Bulbs are sold in quantities of 25. Once you have determined how many bulbs you need, we recommend rounding up to the nearest multiple of 25. If you find you are only a few bulbs short, 5-Packs are available in all colors and color mixes. 

EXAMPLE: I have 21 ft. of roofline to decorate, and my light strings have 8” spacing.   

- Convert 21 feet to inches: 21 x 12 = 252  

- Divide by the socket spacing and round up to the nearest whole number: 252 / 8 = 31.5  >> 32

You will need about 32 bulbs for this job. You can buy two boxes and get 50 bulbs, or one box and two 5-Packs to get 35 bulbs.