Chandelier Size Calculator
Enter the room length, width and ceiling height to get the chandelier diameter by two common rules, the fixture height and the longest drop that keeps 7 ft clear.
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How to use the Chandelier Size Calculator
- Look at the tool above this guide. It starts with the defaults of a 16 × 14 ft room and a 10 ft ceiling.
- Enter your room length in the “Room length” input. Choose the unit (ft, in, cm or m) next to it.
- Enter your room width in the “Room width” input and choose its unit.
- Enter your ceiling height in the “Ceiling height” input and choose its unit.
- Read the two diameter results. One comes from adding the length and width in feet and reading the total as inches. The other comes from the room’s diagonal. The tool shows both and does not average them.
- Read the fixture height range. It is based on 2 to 3 in per foot of ceiling height.
- Read the longest drop. This is the most the fixture, chain or rod can hang from the ceiling while keeping the lowest point at least 7 ft above the floor.
- Read any warning. Warnings appear when a fixture is taller than the available drop, when a ceiling is too low for 7 ft of clearance, when a ceiling is under 8 ft, or when a room or ceiling value falls outside the expected range.
- Compare the diameter and height with the chandelier you are considering.
The tool also has four presets you can select: 12 × 14 ft with an 8 ft ceiling, 14 × 16 ft with a 9 ft ceiling, 18 × 20 ft with a 10 ft ceiling, and 5 × 4 m with a 2.7 m ceiling.
How is the chandelier diameter calculated?
The tool uses two rules of thumb from design guides. Rule 1 adds the room length and room width in feet and reads the total as inches. Rule 2 takes the room’s diagonal in feet and reads that as inches. The two rules often give different answers, and the tool shows both without averaging them.
For a 16 × 14 ft room, rule 1 gives 16 + 14 = 30 in (76.2 cm). Rule 2 gives √(16² + 14²) = 21.3 in (54 cm). The gap is large, so the two numbers work as a range to think about rather than a single answer.
The tool’s table shows both rules for 10 × 12, 12 × 14, 14 × 16, 16 × 18 and 18 × 20 ft rooms. For a 12 × 14 ft room, the table lists 26 in by the sum rule and 18.4 in by the diagonal rule.
Metric rooms work the same way once each side is in feet. For example, a 5 × 4 m room is 16.4042 ft plus 13.1234 ft, which totals 29.5 in by the sum rule.
How tall can a chandelier hang and still clear the floor?
Fixture height is based on ceiling height. Guides suggest 2 to 3 in per foot of ceiling height, so a 10 ft ceiling gives 20 to 30 in (50.8 to 76.2 cm). This rule is given for foyers and for general use, and it is a rule of thumb only.
The longest drop is set by clearance. Guides ask for the lowest point of the fixture to be at least 7 ft (84 in) above the floor where people walk under it. The fixture plus its chain or rod can therefore hang no more than the ceiling height minus 84 in. At 10 ft, that is 120 − 84 = 36 in (91.4 cm).
Take a 12 × 14 ft room with an 8 ft ceiling as an example. The sum rule gives 26 in (66 cm) and the diagonal rule gives 18.4 in (46.8 cm). The fixture height range is 16 to 24 in. The longest drop is 96 − 84 = 12 in, so a 24 in fixture would reach below 7 ft. The tool warns about this case.
These are design rules of thumb, not building codes. The page does not say that any result meets a code or is safe.
Sources (checked 15 October 2026): montreallighting.com · residencesupply.com · settingforfour.com
Worked examples
| Input | Result |
|---|---|
| Room 16 ft × 14 ft, ceiling 10 ft | diameter 30 in (76.2 cm); fixture height 20–30 in (50.8–76.2 cm) |
| Room 12 ft × 14 ft, ceiling 8 ft | diameter 26 in (66 cm); fixture height 16–24 in (40.6–61 cm) |
| Room 18 ft × 20 ft, ceiling 10 ft | diameter 38 in (96.5 cm); fixture height 20–30 in (50.8–76.2 cm) |
| Room 5 m × 4 m, ceiling 2.7 m | diameter 29.5 in (75 cm); fixture height 17.7–26.6 in (45–67.5 cm) |
Calculated by the tool above; open it with the same values to see each step.
Frequently asked questions
Is the chandelier size calculator free to use?
Yes. The tool is free, runs in your browser, and needs no sign-up. Nothing you enter is uploaded.
Why do the two diameter results differ?
Each result comes from a different design rule. The sum rule adds the room’s length and width, while the diagonal rule uses the room’s corner-to-corner distance. Both are shown, so you can see the range rather than a single averaged figure.
What does the longest drop mean?
The longest drop is the most a fixture, chain or rod can hang from the ceiling. It keeps the lowest point at least 7 ft (84 in) above the floor. It is calculated as ceiling height minus 84 in.
What does the warning about a fixture being too tall mean?
The warning appears when the fixture height range is taller than the available drop. For example, a 12 × 14 ft room with an 8 ft ceiling has a 12 in drop, which is less than the 16 to 24 in fixture height range.
Can I enter measurements in metres?
Yes. Each input has its own unit selector, so you can enter length, width and ceiling height in ft, in, cm or m. The tool converts them for the calculations.
Does the tool check whether my chandelier is safe?
No. The results are design rules of thumb calculated from your inputs. They are not building codes, and the tool does not say that any result meets a code or is safe. Check the product’s dimensions and your local requirements before you install.
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