30 60 90 Triangle Calculator
Calculate the side lengths, area, and perimeter of a 30-60-90 right triangle given one side.
Published by:
isCalculator Editorial Team
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How to use this tool?
How to Use the 30-60-90 Triangle Calculator
- Enter a side length in the "Side Length" field. Use any positive number (e.g., 5, 2.5). No specific unit is required—just be consistent (e.g., all in inches or all in cm).
- Select which side you entered from the "Known Side" dropdown:
- Short Leg – opposite the 30° angle (the smallest side).
- Long Leg – opposite the 60° angle.
- Hypotenuse – opposite the 90° angle (the longest side).
- Click "Calculate". The calculator will instantly compute all three sides, area, and perimeter based on the fixed ratio 1 : √3 : 2.
- Read the results below. All values are displayed to 4 decimal places. The formula reminder confirms the ratio used.
Tip: If you see an error, ensure the side length is a positive number (e.g., not zero or negative). No other formatting is needed.
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Frequently Asked Questions
A 30-60-90 triangle is a right triangle with angles 30°, 60°, and 90°. Its sides are in the ratio 1 : √3 : 2.
If you know one side, use the ratio: short leg = hypotenuse/2, long leg = short leg * √3, hypotenuse = short leg * 2.
Any consistent unit (e.g., inches, cm). The calculator works with any positive number.
