Christmas Lights Calculator

Calculate exact light counts, strand needs, and energy costs for your holiday display

Lights Needed

700

Strands

Watts

49W

Monthly Cost

$1.06

Tree Height (ft)

Light Density

Light Type

Hours Per Day

Electricity Rate ($/kWh)

Lights Needed

700

7 strands of 100

Total Watts

49W

0.07W/bulb

Monthly Cost

$1.06

6 hrs/day

Season Cost (6 weeks)$1.59

Based on 6 hours/day at $0.12/kWh

LED vs Incandescent Cost

LED Monthly$1.06

Incandescent Monthly$7.56

LED saves $6.50/month (86% less)

Breakdown

Total Lights700

Strands Needed7 (100/strand)

Power Draw49W

Light TypeLED

Safety Tips

•Never connect more than 3 strands end-to-end (300 lights per outlet)
•Use outdoor-rated lights (UL/ETL listed) for exterior displays
•Use a timer to automatically turn lights off and save energy
•Inspect all strands for frayed wires or broken sockets before use
•Keep connections off the ground and away from standing water

Example Calculations

17-Foot Christmas Tree (Standard)

Inputs

Tree Height7 ft

DensityStandard (100/ft)

Light TypeLED mini

Result

Lights Needed700

Strands7

Total Watts49W

Monthly Cost$1.06

7 ft × 100 lights/ft = 700 lights. 700 ÷ 100 = 7 strands. Power: 700 × 0.07W = 49W. Monthly: (49 × 6 × 30) / 1000 × $0.12 = $1.06.

280-Foot Roofline with Mini Lights

Inputs

Roofline Length80 ft

Bulb TypeMini (6" spacing)

Light TypeLED

Result

Lights Needed176

Strands2

Total Watts12.32W

Monthly Cost$0.27

80 ft × 2 per ft = 160, plus 10% overlap = 176 lights. Power: 176 × 0.07W = 12.32W. Monthly: (12.32 × 6 × 30) / 1000 × $0.12 = $0.27.

34 Bushes (3 ft × 3 ft each)

Inputs

Bush Count4

Height3 ft

Width3 ft

Result

Lights Needed1,800

Strands18

Total Watts126W

Monthly Cost$2.72

Per bush: 3 × 3 × 50 = 450 lights. Total: 450 × 4 = 1,800. Power: 1,800 × 0.07W = 126W. Monthly: (126 × 6 × 30) / 1000 × $0.12 = $2.72.

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Frequently Asked Questions

How many lights do I need for a Christmas tree?

The standard rule is 100 lights per foot of tree height. A 7-foot tree needs about 700 lights (7 strands of 100). For a fuller look, use 150–200 lights per foot. Density depends on branch spacing and personal preference.

Standard coverage: 100 lights per foot = 700 for a 7-ft tree
Full coverage: 150 lights per foot = 1,050 for a 7-ft tree
Bright/dense: 200 lights per foot = 1,400 for a 7-ft tree
Pre-lit trees typically come with 100–150 lights per foot
Wide trees (6+ ft diameter) may need 20–30% more than standard

Tree Height	Standard (100/ft)	Full (150/ft)	Bright (200/ft)
4 ft	400	600	800
6 ft	600	900	1,200
7 ft	700	1,050	1,400
9 ft	900	1,350	1,800
12 ft	1,200	1,800	2,400

How much does it cost to run Christmas lights?

LED Christmas lights cost very little to run. A 700-light LED display uses about 49 watts and costs roughly $1.06 per month at 6 hours/day. Incandescent lights use 7–10x more electricity, costing $7–15 per month for the same display.

LED mini light: 0.07W per bulb vs incandescent: 0.5W per bulb
700 LED lights at 6 hrs/day = ~$1.06/month at $0.12/kWh
700 incandescent lights at 6 hrs/day = ~$7.56/month at $0.12/kWh
LED C9 bulbs: 0.6W each vs incandescent C9: 7W each
Switching to LED saves 85–93% on electricity for holiday lights

Light Type	Watts/Bulb	700 Lights (W)	Monthly Cost
LED Mini	0.07W	49W	$1.06
Incandescent Mini	0.5W	350W	$7.56
LED C9	0.6W	420W	$9.07
Incandescent C9	7W	4,900W	$105.84

How many lights do I need for roofline and gutters?

For roofline lights, measure the total linear footage of your roofline and add 10% for corners and overlap. Mini lights at 6-inch spacing need 2 bulbs per foot. C9 bulbs at 12-inch spacing need 1 per foot. An 80-foot roofline needs about 176 mini lights or 88 C9 bulbs.

Mini lights (6" spacing): 2 per foot + 10% = 176 for 80 ft
C9 bulbs (12" spacing): 1 per foot + 10% = 88 for 80 ft
Average single-story home roofline: 60–100 linear feet
Two-story homes: 100–160 linear feet including gables
Always add 10% extra for corners, peaks, and connection overlap

How do I wrap bushes and shrubs with lights?

For bushes, use the formula: height × width × 50 lights per square foot of foliage face. A typical 3-foot-tall, 3-foot-wide bush needs about 450 mini lights. Use net lights for even coverage on round or flat-topped bushes.

Formula: height (ft) × width (ft) × 50 = lights needed per bush
3 ft × 3 ft bush = 450 lights (4–5 strands)
4 ft × 4 ft bush = 800 lights (8 strands)
Net lights (4×6 ft) cover bushes faster and more evenly
Use mini lights for dense foliage, C6 for sparse/open shrubs

What are the safety rules for Christmas lights?

Never connect more than 3 standard strands (300 lights) end-to-end on one outlet. Use outdoor-rated UL or ETL-listed lights for exterior displays. Always inspect strands for damage before hanging and use a timer to limit operating hours.

Maximum 3 strands (300 lights) per outlet for standard mini lights
Use GFCI-protected outlets for all outdoor light connections
Outdoor lights must be rated for exterior use (UL/ETL wet-location)
Never use staples or nails to attach lights – use plastic clips
LED lights run cooler and are safer near dry foliage and trees

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Christmas Lights Calculator

Calculate exact light counts, strand needs, and energy costs for your holiday display

Lights Needed

700

Strands

Watts

49W

Monthly Cost

$1.06

Tree Height (ft)

Light Density

Light Type

Hours Per Day

Electricity Rate ($/kWh)

Lights Needed

700

7 strands of 100

Total Watts

49W

0.07W/bulb

Monthly Cost

$1.06

6 hrs/day

Season Cost (6 weeks)$1.59

Based on 6 hours/day at $0.12/kWh