# How Accurate is our Area Calculator?

So you’ve trialed SketchAndCalc™, but just how accurate is our area calculator?

Area of Regular Polygon Shapes
Based on the number of vertices (control points), and the angles between them, SketchAndCalc™ automatically detects whether a Square, Rectangle or Circle is present.

For these regular polygons, a formula is chosen to calculate area based on the length of the perimeter sides (or circle diameter). How Accurate is our Area Calculator? It’s accurate to 10,000 decimal places.

Area of Irregular Polygon Shapes
Shapes with sides of any length and interior angles of any measure use the polygon method of calculation, also known as the ‘Shoelace, or Surveyor’s formula’.

Given the nature of drawing or tracing shapes on a screen, the more faithfully a shape is traced, or described, the more accurate the results.

Therefore, area result inaccuracy can be greatly reduced by adjusting the canvas zoom level, drawing slowly, and using a high-resolution image (if tracing over an image).

One important note to consider when tracing an area over an image or photograph is whether the horizontal and vertical dimensions of the imported image are a true 1:1 ratio. Images can sometimes be scaled in one dimension, making any attempt to calculate its true area impossible.

SketchAndCalc™ also has many drawing techniques that can be used to improve the accuracy of drawing irregular areas.

Such as:

Manually enter a line length

Fine adjust the position of a vertex

Delete a stray vertex

Add a vertex to better describe the perimeter

Draw fixed angles

Draw circular shapes

Draw with a stylus (Mobile app)

Draw curves slowly

With irregular area calculations, rounding up line lengths is required to avoid unnecessarily large arrays of numbers that would detrimentally impact performance when working with 10,000 decimal places.

So, how accurate is our area calculator? Tests have shown this rounding results is a negligible variance of 0.002%.