Calculate length-to-diameter ratio, length, or diameter from any two values with inches, feet, centimeters, or meters and show the formula.
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Length-To-Diameter Ratio Formula
The length-to-diameter ratio compares the total length of an object to its diameter. The ratio is unitless, but length and diameter must be in the same unit before dividing.
R = L / D
L = R * D
D = L / R
- R = length-to-diameter ratio, unitless
- L = total length
- D = total diameter
If you enter length and diameter, the calculator finds the ratio by dividing length by diameter.
If you enter diameter and ratio, it finds the required length by multiplying diameter by the ratio.
If you enter length and ratio, it finds the diameter by dividing length by the ratio.
The calculator converts length and diameter to a common unit before calculating. This prevents errors when one value is entered in inches and the other is entered in feet, centimeters, or meters.
Common Unit Conversions for Length and Diameter
| Unit | In Inches | Use In The Calculator |
|---|---|---|
| 1 inch | 1 in | in |
| 1 foot | 12 in | ft |
| 1 centimeter | 0.393701 in | cm |
| 1 meter | 39.3701 in | m |
How to Read Length-To-Diameter Ratios
| Ratio | Meaning | Example If Diameter Is 2 in |
|---|---|---|
| 1:1 | Length equals diameter | Length = 2 in |
| 5:1 | Length is 5 times the diameter | Length = 10 in |
| 10:1 | Length is 10 times the diameter | Length = 20 in |
| 20:1 | Length is 20 times the diameter | Length = 40 in |
Example Problems
Example 1: Find the length-to-diameter ratio
You have a rod with a length of 48 inches and a diameter of 4 inches.
R = L / D
R = 48 / 4 = 12
The length-to-diameter ratio is 12, or 12:1.
Example 2: Find the diameter
You have a length of 2 meters and a length-to-diameter ratio of 10.
D = L / R
D = 2 / 10 = 0.2 m
The diameter is 0.2 meters.
FAQ
Is the length-to-diameter ratio a unitless number?
Yes. The ratio is unitless because length is divided by diameter. The units cancel out as long as both values are converted to the same unit first.
Can length and diameter be entered in different units?
Yes. You can enter length and diameter in different supported units. The calculator converts both values to a common base unit before calculating the result.
What does a 10:1 length-to-diameter ratio mean?
A 10:1 ratio means the length is 10 times the diameter. For example, if the diameter is 3 inches, the length is 30 inches.
