Frequently Asked Questions
Everything you need to know about the Area Calculator.
Which shapes are supported?
Triangle, rectangle, square, circle, trapezoid, parallelogram, rhombus, regular polygon, ellipse, and circular sector.
How is triangle area calculated?
Either from base and height (½bh), or from all three sides using Heron's formula.
Does it show the formula used?
Yes, each shape shows its formula with your values substituted in.
How is regular polygon area calculated?
Using the formula based on number of sides and side length (or apothem), not an approximation.
Are circle-based results exact?
Yes, shown in π-form (e.g. 25π) alongside the decimal.
What units does it use?
It's unit-agnostic; results are labeled in units² matching whatever unit you entered.
What if my triangle sides are invalid?
The triangle inequality is checked, and invalid combinations are flagged.
Can I calculate a sector's area?
Yes, enter the circle's radius and the sector's central angle.
Is it free?
Completely free, no sign-up or limits.
Does it work on mobile?
Yes, fully responsive.