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Right Triangle Side and Angle Calculator.

Solve the hypotenuse and acute angle from two legs.

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Set your values

Results update as you type.

02 / ANSWER

Opposite leg

Adjacent leg

Opposite must be finite.

Results update automatically as you type.

Use Cases

Construction and Carpentry

Quickly determine the length of a diagonal brace or rafter and the angle to cut for a right-angled corner.

Example: If a wall is 8 ft high and the base is 6 ft away, the brace length is 10 ft.

Education and Homework

Verify solutions for right triangle problems in geometry or trigonometry classes.

Example: Check that a triangle with legs 3 and 4 has a hypotenuse of 5 and angles of 36.87° and 53.13°.

Frequently Asked Questions

How do I use the Right Triangle Side Angle Calculator?: Enter the lengths of the opposite and adjacent legs (in any consistent unit) into the corresponding fields. The calculator instantly computes the hypotenuse, the two acute angles, and the area of the right triangle.
What formulas does the calculator use?: It uses the Pythagorean theorem (hypotenuse = √(opposite² + adjacent²)) for the hypotenuse, and trigonometric ratios (tan(angle) = opposite/adjacent) to find the angles. The area is (opposite × adjacent) / 2.
Can I use any unit of measurement?: Yes, as long as both leg lengths are in the same unit. The calculator treats the inputs as numbers and outputs the hypotenuse in the same unit, and angles in degrees.

Tips & Common Mistakes

Tips

Ensure both leg lengths are in the same unit before entering them.
For precise angle measurements, use more decimal places in your inputs.
Remember that the sum of the two acute angles is always 90°.
Use the area result to cross-check your calculations if needed.

Common Mistakes to Avoid

Mixing units (e.g., feet and inches) without converting to a single unit.
Entering the hypotenuse as one of the legs; this calculator only accepts the opposite and adjacent legs.
Assuming the angle output is in radians when it is actually in degrees.

Last updated: August 13, 2026

Use Cases

Construction and Carpentry

Quickly determine the length of a diagonal brace or rafter and the angle to cut for a right-angled corner.

Example: If a wall is 8 ft high and the base is 6 ft away, the brace length is 10 ft.

Education and Homework

Verify solutions for right triangle problems in geometry or trigonometry classes.

Example: Check that a triangle with legs 3 and 4 has a hypotenuse of 5 and angles of 36.87° and 53.13°.

Frequently Asked Questions

How do I use the Right Triangle Side Angle Calculator?

Enter the lengths of the opposite and adjacent legs (in any consistent unit) into the corresponding fields. The calculator instantly computes the hypotenuse, the two acute angles, and the area of the right triangle.

What formulas does the calculator use?

It uses the Pythagorean theorem (hypotenuse = √(opposite² + adjacent²)) for the hypotenuse, and trigonometric ratios (tan(angle) = opposite/adjacent) to find the angles. The area is (opposite × adjacent) / 2.

Can I use any unit of measurement?

Yes, as long as both leg lengths are in the same unit. The calculator treats the inputs as numbers and outputs the hypotenuse in the same unit, and angles in degrees.

Tips & Common Mistakes

Tips

Ensure both leg lengths are in the same unit before entering them.
For precise angle measurements, use more decimal places in your inputs.
Remember that the sum of the two acute angles is always 90°.
Use the area result to cross-check your calculations if needed.

Common Mistakes to Avoid

Mixing units (e.g., feet and inches) without converting to a single unit.
Entering the hypotenuse as one of the legs; this calculator only accepts the opposite and adjacent legs.
Assuming the angle output is in radians when it is actually in degrees.

Use Cases

Construction and Carpentry

Quickly determine the length of a diagonal brace or rafter and the angle to cut for a right-angled corner.

Example: If a wall is 8 ft high and the base is 6 ft away, the brace length is 10 ft.

Education and Homework

Verify solutions for right triangle problems in geometry or trigonometry classes.

Example: Check that a triangle with legs 3 and 4 has a hypotenuse of 5 and angles of 36.87° and 53.13°.

Frequently Asked Questions

How do I use the Right Triangle Side Angle Calculator?

What formulas does the calculator use?

Can I use any unit of measurement?

Yes, as long as both leg lengths are in the same unit. The calculator treats the inputs as numbers and outputs the hypotenuse in the same unit, and angles in degrees.

Tips & Common Mistakes

Tips

Ensure both leg lengths are in the same unit before entering them.
For precise angle measurements, use more decimal places in your inputs.
Remember that the sum of the two acute angles is always 90°.
Use the area result to cross-check your calculations if needed.

Common Mistakes to Avoid

Mixing units (e.g., feet and inches) without converting to a single unit.
Entering the hypotenuse as one of the legs; this calculator only accepts the opposite and adjacent legs.
Assuming the angle output is in radians when it is actually in degrees.