Triangle Area Calculator

Fill in any two of base, height and area, then click Calculate. The tool uses Area = Base × Height ÷ 2 to compute the remaining value automatically.

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Please fill exactly two of base, height and area, leave one blank, and the calculator will find the missing value.
Result
Triangle Area Diagram
三角形面积计算公式: \(S = \frac{1}{2} b h\)
A
Find Base
Fill fields:
Height Area
and leave blank:
Base
B
Find Height
Fill fields:
Base Area
and leave blank:
Height
C
Find Area
Fill fields:
Base Height
and leave blank:
Area

About Triangle Area Calculator

This calculator is based on the triangle area formula: Area = Base × Height ÷ 2. Knowing any two of base, height and area lets you solve for the third.

If you know base and height, Area = Base × Height ÷ 2. If you know area and base, Height = 2 × Area ÷ Base. If you know area and height, Base = 2 × Area ÷ Height.

Triangle area is widely used in roof design, land measurement, structural engineering and graphic design. This tool lets you perform these conversions quickly.

Make sure all values are greater than 0 and use consistent units (for example, all in meters, centimeters or millimeters) so the result remains meaningful.

Quiz: Test Your Triangle Area Knowledge

1. What is the basic formula for the area of a triangle?

Area = Base × Height ÷ 2.

2. If a triangle has a base of 6 m and a height of 4 m, what is its area?

Area = 6 × 4 ÷ 2 = 12 m².

3. If the area of a triangle is 10 m² and the base is 5 m, what is the height?

Height = 2 × Area ÷ Base = 2 × 10 ÷ 5 = 4 m.

4. Why does the triangle area formula include division by 2?

Because a triangle can be seen as half of a rectangle with the same base and height, so its area is half the rectangle’s.

5. Can you use the same formula for right triangles?

Yes. Take one leg as the base and the other leg as the height, then Area = Base × Height ÷ 2.

6. Why must the units of base and height be consistent when using this tool?

If the units differ, for example meters and centimeters, the computed area will not correctly reflect the real size.

7. Can you directly use this tool if you only know the three side lengths of a triangle?

No. This calculator is based on the base-height formula. For three sides you would use Heron’s formula, which is a different method.

8. Can you use decimal values for base, height or area?

Yes. All three fields accept decimal values for more precise calculations.

9. Who can benefit from this triangle area calculator?

Students, teachers, engineers, designers and anyone who needs triangle area conversions.

10. Why can base or height not be negative in this calculator?

Base and height represent physical dimensions and must be positive; negative values have no geometric meaning.

Triangle Area Calculator

This tool helps you find the third value when any two of base, height and area of a triangle are known. Useful for learning, design and everyday geometry calculations.

Scan the QR code to use this tool on mobile.