Christmas Tree Size Calculator
Not sure what size tree to buy? Enter your ceiling height and the floor space you have, and this tool finds the largest tree that fits. It leaves room for the stand, the topper and a small gap at the ceiling and on each side.
You get the tallest tree your ceiling allows, the tallest your floor space allows, and which one limits you. You also get a size to shop for, rounded down to the nearest half foot, with its approximate width and the headroom left over.
How to use it
- Measure the ceiling height at the lowest point over the tree, and the width of the spot where it will go.
- Enter the stand height, the topper height and the gaps you want to keep clear.
- Pick a tree shape: full, standard or slim.
- Read the tallest tree that fits, what limits it, and the size to shop for.
How it works
Height by ceiling = (ceiling height x 12 - ceiling gap - stand - topper) ÷ 12; Height by space = (floor width x 12 - 2 x side gap) ÷ shape ratio ÷ 12; Best height = the smaller of the two
Ceiling height and floor width are in feet. Stand, topper and gaps are in inches, so the ceiling formula multiplies feet by 12 and divides the result by 12 to return to feet. The shape ratio is the tree width divided by its height: 0.6 for a full tree, 0.5 for a standard tree or 0.4 for a slim one. Any other shape value is rejected. If the stand, topper and gap use up the whole ceiling height, or the side gaps use up the whole floor width, the tool shows a message instead of a size.
Example with the default values: the ceiling allows (96 - 6 - 4 - 10) ÷ 12 = 6.3 ft, and the floor allows (48 - 12) ÷ 0.5 ÷ 12 = 6.0 ft. The floor space is the limit, so the best height is 6.0 ft. Decimal feet convert to inches by multiplying the part after the point by 12, so 6.3 ft is about 6 ft 4 in.
The size to shop for is the best height rounded down to the nearest half foot up to 10 feet, and down to the nearest whole foot above that. Its width is that height x the shape ratio x 12 inches. Headroom is the ceiling height in inches minus the shop height, stand and topper. It includes your ceiling gap plus any extra inches lost to rounding down or to the floor limit. In the example, that is 6 in of gap plus 4 in unused, or 10 in. Real trees vary, so treat the width as a close estimate and check the maker's listed dimensions.
Worked example
| Ceiling height | 8 ft |
|---|---|
| Floor space width | 6 ft |
| Tree stand height | 4 in |
| Topper height | 12 in |
| Gap below the ceiling | 6 in |
| Gap on each side | 6 in |
| Tree shape | Standard (width about 50% of height) |
| Tallest tree that fits | 6.2 ft |
| What limits the size | Ceiling height |
| Tallest by ceiling height | 6.2 ft |
| Tallest by floor space | 10 ft |
| Size to shop for | 6 ft |
| Approximate width at that size | 36 in |
| Space left below the ceiling | 8 in |
Questions and answers
How much space should I leave between the tree and the ceiling?
Many people leave about 6 inches or more above the topper. That keeps the topper from touching the ceiling and makes setup easier. Raise the gap if you have a ceiling fan or light fixture nearby.
Does the tree height include the stand?
It depends on the listing, so check whether it includes the base. This tool subtracts the stand height you enter. If the listed height already includes the base, enter 0 for the stand.
How wide is a Christmas tree?
It depends on the shape. A full tree is often about 60% as wide as it is tall, a standard tree about 50%, and a slim or pencil tree about 40%. A 7.5-foot standard tree is roughly 45 inches wide.
Why does the tool say floor space is my limit?
A wide tree needs more room than a narrow one of the same height. If the floor space allows a shorter tree than the ceiling does, the space is the limit. A slimmer shape or smaller side gaps can raise it.
Where should I measure the ceiling height?
Measure from the floor to the ceiling at the spot where the tree will stand. If the ceiling slopes or has a beam, ceiling fan or light fixture overhead, use the lowest point above the tree's footprint.
Do I need to count the topper?
Yes, if you plan to use one. A star or angel adds inches above the tree tip, so enter its height. Enter 0 if you will not use a topper.