Calculate height, width, or size ratio from any two values, with length units in meters, centimeters, millimeters, inches, or feet.
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Size Ratio Formula
The size ratio compares total height to total width. The calculator uses the height-to-width ratio, written as height:width.
R = H / W
H = W * R
W = H / R
R = a / b
- H = total height
- W = total width
- R = numeric size ratio
- a:b = ratio entered as height:width, such as 4:3 or 16:9
- a = height part of the ratio
- b = width part of the ratio
If you enter height and width, the calculator finds the ratio by dividing height by width. The result is shown as a ratio against 1, such as 1.3333:1.
If you enter height and ratio, the calculator finds width by dividing height by the numeric ratio. If you enter width and ratio, it finds height by multiplying width by the numeric ratio.
Height and width can use different length units. The calculator converts both measurements to meters internally, performs the calculation, then converts the missing value back to the unit you selected.
Common Height-to-Width Ratios
| Ratio | Decimal Height ÷ Width | Common Use |
|---|---|---|
| 1:1 | 1.0000 | Square images, tiles, icons |
| 4:3 | 1.3333 | Older displays, photos, slides |
| 3:2 | 1.5000 | Photography prints and sensors |
| 16:9 | 1.7778 | Widescreen video and displays |
| 21:9 | 2.3333 | Ultrawide screens |
Length Unit Conversion Reference
| Unit | Meters per Unit | Example |
|---|---|---|
| Meter | 1 | 2 m = 2 m |
| Centimeter | 0.01 | 100 cm = 1 m |
| Millimeter | 0.001 | 1000 mm = 1 m |
| Inch | 0.0254 | 12 in = 1 ft |
| Foot | 0.3048 | 3 ft = 0.9144 m |
Example Size Ratio Calculations
Example 1: Find the size ratio
You have a height of 8 inches and a width of 6 inches.
R = 8 / 6 = 1.3333
The size ratio is 1.3333:1. This is equivalent to 4:3.
Example 2: Find the missing width
You have a height of 120 cm and a size ratio of 4:3.
R = 4 / 3 = 1.3333
W = 120 / 1.3333 = 90
The missing width is 90 cm.
FAQ
What does a size ratio mean?
A size ratio tells you how height compares to width. A ratio of 4:3 means the height has 4 parts for every 3 parts of width. The actual unit does not matter as long as both measurements are converted consistently.
Can height and width use different units?
Yes. You can enter height in one unit and width in another unit. The calculator converts both values to meters before calculating the ratio or missing measurement.
Why does the calculated ratio show as something like 1.7778:1?
When height and width are entered, the calculator divides height by width and reports the result against 1. For example, 16:9 becomes 1.7778:1 because 16 divided by 9 is approximately 1.7778.
