Triangle Area Calculator
Use your own numbers after reviewing the formula and worked example.
Quick answer
Triangle area uses a base and the perpendicular height to that base.
Formula or method
Keep units, percentages and time periods consistent. The formula is useful as a transparent check on the calculator result and helps explain why changing one input changes the answer.
Step-by-step
- Choose a base.
- Find the perpendicular height.
- Multiply base by height.
- Divide by two and report square units.
Worked example
A triangle with base 10 ft and perpendicular height 6 ft has area 30 sq ft.
How to interpret the result
The height does not need to be a side; it must be perpendicular to the chosen base.
When the answer is used for a purchase, loan, payroll decision, construction order, school grade, health estimate or other real-world choice, verify the assumptions that matter in that context. Accurate arithmetic still depends on accurate inputs.
Common mistakes
- Using a slanted side as height.
- Forgetting one-half.
- Reporting linear units.
Frequently asked questions
Can any side be the base?
Yes, with its corresponding perpendicular height.
What units are used?
Square units.
Can area be found from three sides?
Yes, with Heron’s formula.