45-45-90 triangle calculator
A 45-45-90 triangle is half of a square cut along its diagonal, so the two legs are equal and the hypotenuse is the diagonal.
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How to use it
- Enter known side and side length.
- The result appears straight away and updates as you edit.
- Copy the result, or copy a link that keeps the same values to share it.
How it is calculated
Leg x, hypotenuse x√2. From the hypotenuse: x = hypotenuse / √2. Area = x² / 2.
Example
Inputs: Known side = Leg, Side length = 5. Result: Hypotenuse: 7.0711; Each leg: 5; Area: 12.5.
Limits and caveats
- Only for a right triangle whose two acute angles are both 45 degrees.
Questions about this tool
What is the side ratio of a 45-45-90 triangle?
1 : 1 : √2. The hypotenuse is a leg times about 1.414.
Can I use this to get the diagonal of a square?
Yes. Enter the side of the square as the leg and the hypotenuse is the diagonal.
How do I get a leg from the hypotenuse?
Divide the hypotenuse by √2, for example 10 / 1.414 ≈ 7.071.