Christmas lights calculator

Pick your tree and what you want lit outside. You get how many light strands to buy, how many outlets you need so nothing trips, and what it all costs to run for the season. Your numbers stay on this device.

Tree height

How bright on the tree

Bulbs

Roofline to light (feet)

Bushes

Windows to outline

Roofline style

Hours, days and power price

Hours on each night

Days up

Power price ($ per kWh)

US average is about 17 cents. Your bill shows your price per kWh.

Strands to buy

Circuits needed

Cost for the season

Shopping list

Plug it in safely

Lights done? Plan the gifts

The Christmas Gift Planner spreadsheet (Excel and Google Sheets) keeps every person, gift idea, price and budget in one place and shows what is left to spend.

See the Gift Planner

How it counts

Tree: 50, 100 or 180 mini lights per foot of height. Strands are 100-light sets. Roofline: C9 bulbs 1 per foot in 25-foot strings, mini lights 100 per 22 feet, icicle 150 per 7.5 feet. Bushes: 150 lights each. Windows: about 15 feet of mini lights each. Power: LED mini 0.07 W, old-style mini 0.4 W, LED C9 0.6 W, old-style C9 7 W per bulb. Circuits: 15 amp at 120 V, loaded to 80% (1440 W).