Calculator Free is a free calculator app for Android that offers users an easy-to-use interface with customizable themes. Developed by Tom Hogenkamp, this app allows users to style the background and buttons of the calculator. There are several themes included, but users can also create their own theme by choosing a background image from the gallery and selecting text colors that ensure clear readability.

In addition to its customizable themes, Calculator Free also supports all basic functionality for daily-life situations. The entered equation is always shown, together with the intermediate result, making it easy to follow calculations. The calculator supports addition, subtraction, multiplication, and division, as well as percentages and parentheses. The app also includes scientific notation and memory options for making more complex calculations. By touching the buttons, the device vibrates to provide feedback that the button is pressed.

The full sum is displayed above the input display, so users know exactly what they have calculated. The answer is also colored differently, making it clear that the number displayed is the answer. Additionally, wrong inputs are corrected automatically, ensuring accurate calculations. Overall, Calculator Free is an intuitive and practical calculator app that is completely free to use.