How this calculator works
The rule is 300 lights for every metre of tree height for a full look (about 90 per foot), 150 per metre for a light one and 450 for a dense one. UK retailer guides range from about 80 to nearly 500 lights per metre, and many quote 100 per foot as a minimum. Shop sizes are rounded: a 6ft tree is sold as 1.8 m and a 7ft tree as 2.1 m, and we use those sizes. Multiply the height in metres by the lights per metre, then divide by the lights in each set and round up.
Worked example: a 6ft (1.8 m) tree at 300 lights per metre needs 540 lights, which is 3 sets of 200 (600 lights). A 7ft (2.1 m) tree needs 630 lights, or 4 sets of 200. At 450 per metre a 7ft tree needs 945 lights, which is 2 sets of 500 (1,000 lights).
The wire length depends on the gap between the bulbs: the 600 lights in 3 sets of 200, 5 cm apart, make 30 m of lit wire (the lights you will hold, not just the 540 needed). Wider spacing means a longer set for the same number of bulbs. The tree size calculator shows which tree fits your ceiling, and its size pages give the same lights for each tree size.
Assumptions and sources
The assumptions behind your numbers (waste, sizes, rates) are listed in the notes directly under your results, and they update when you change an input.
The formula and a worked example are shown above, so you can check any result by hand. Read how we calculate and check our numbers. Results are estimates for planning: supplier products vary, so check the size printed on the label.
Lights for common tree heights
Sets of 200 lights, at three levels of fullness (150, 300 and 450 per metre). Heights are the shop sizes in feet, with the metres beside them.
| Tree height | 150 per metre | 300 per metre | 450 per metre |
|---|---|---|---|
| 4 ft (1.2 m) | 180 lights (1 set of 200) | 360 lights (2 sets of 200) | 540 lights (3 sets of 200) |
| 5 ft (1.5 m) | 225 lights (2 sets of 200) | 450 lights (3 sets of 200) | 675 lights (4 sets of 200) |
| 6 ft (1.8 m) | 270 lights (2 sets of 200) | 540 lights (3 sets of 200) | 810 lights (5 sets of 200) |
| 7 ft (2.1 m) | 315 lights (2 sets of 200) | 630 lights (4 sets of 200) | 945 lights (5 sets of 200) |
| 8 ft (2.4 m) | 360 lights (2 sets of 200) | 720 lights (4 sets of 200) | 1,080 lights (6 sets of 200) |
| 10 ft (3.0 m) | 450 lights (3 sets of 200) | 900 lights (5 sets of 200) | 1,350 lights (7 sets of 200) |
Tips before you buy
- Test every set before you put it on the tree, and replace any that do not light. It is much harder once they are wrapped around the branches.
- Start at the top and work down, or from the trunk out along each branch for a deeper look. Weave the lights in rather than wrapping them around the outside.
- Check the label for how many sets can be joined end to end, and do not overload an extension lead.
- Choose a tree that ends at least 30 cm (1 ft) below the ceiling, so the stand and topper fit.
- Use a timer so the lights are not left on all night, and switch them off when you go out.
Tools & materials for this project
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Frequently asked questions
How many lights do I need for a 6ft Christmas tree?
About 540 at 300 per metre, which is 3 sets of 200. Use about 270 for a light look and 810 for a dense one.
How many lights for a 7ft Christmas tree?
About 630 at 300 per metre (4 sets of 200), or 945 for a dense look.
How many lights for a 1.8 m tree?
The same as a 6ft tree, about 540 lights at 300 per metre.
Are LED Christmas tree lights better than older bulbs?
Mostly yes. LEDs use far less power, stay cool, last longer, and more sets can usually be joined on one plug. Check the label for the limit.
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Related calculators & guides
Estimates only. Results assume standard materials and simple shapes. Supplier products vary, and the final call on quantity, structure and safety is yours. Check the Building Regulations and your supplier's guidance before ordering.