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Calculate the area of a triangle using base and height, two sides and the included angle, or Heron's formula. Ideal for math studies and engineering measurements.
Overview
Understand what the tool solves, how it works, and the boundaries of its data.
This calculator finds a triangle’s area from a base length and the perpendicular height corresponding to that base. “Perpendicular” means that the height meets the base line at a right angle. The height is not generally the length of one of the sloping sides.
Area = (base × perpendicular height) ÷ 2
The factor of one-half accounts for a triangle occupying half the area of a parallelogram with the same base and perpendicular height. The result is displayed to four decimal places. If both inputs are measured in inches, the result is square inches; if both are in feet, it is square feet. The calculator has no separate unit selector.
For example, a base of 10 inches and corresponding height of 6 inches gives (10 × 6) ÷ 2 = 30 square inches.
Guide
Follow the workflow and verify inputs and outputs with practical examples.
Any side may serve as the base. Use the height measured from the opposite vertex at 90 degrees to the line containing that side.
Enter both lengths in the same unit. Convert one value first if one measurement is in inches and the other is in feet or centimeters.
Multiply the two lengths and divide by two. The displayed number is the area in the corresponding square unit, rounded to four decimal places.
| Base | Perpendicular height | Area |
|---|---|---|
| 10 in | 6 in | 30 in² |
| 8 ft | 5 ft | 20 ft² |
| 12 cm | 7.5 cm | 45 cm² |
For an obtuse triangle, the perpendicular height may meet the extension of the chosen base outside the triangle. It is still the matching height for the area formula.
Use cases
See how the tool fits into real work and everyday tasks.
Use the given base and matching altitude, then compare the calculator’s result with your written substitution into the formula.
For a triangular panel or garden section, measure a side and its perpendicular height in one unit before using the result as an area estimate.
When dimensions are marked on a plan, verify that the height is perpendicular to the selected edge rather than a diagonal side length.
Q&A
Find concise answers to common questions and confusing cases.
No. One value must be a base and the other its corresponding perpendicular height. Two side lengths alone may not determine the area.
No. This calculator does not use Heron’s formula or derive a height from three sides. You need the base and its perpendicular height.
Convert the measurements to the same unit first. Otherwise the product and resulting square unit will be inconsistent.
Area multiplies one length by another. Two measurements in inches produce square inches; two measurements in feet produce square feet.
Notes
Review scope, result limitations, and important precautions before use.
The result is only as reliable as the measurements entered. A sloping side used in place of the perpendicular height changes the answer. This calculator does not validate the triangle’s geometry, infer an unknown measurement, or accept three sides or two sides with an included angle. For construction, surveying, or other precision work, follow the applicable measurement procedure and check source dimensions independently.
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