Simple-Stone provides a simple means to convert from stones and pounds to kilograms or grams by sliding a finger across the iPhone screen. The display separately shows the pound and stone values; touching either sets the slide to increment in units of that value, changing the metric display accordingly, in a large, easy to read font.

Sliding a finger across the metric value increases or decreases the number of decimal digits displayed. Touching the metric value sets the slide to increment in the right-most metric digit shown. The sensitivity of the slide - how much the units increase (or decrease) with a given slide length - can be controlled through the properties of the app.

Rotating the iPhone provides different interfaces for left- and right-handed users; double tapping the slide-area resets the displayed value to zero.

Simple-Stone: the simplest route from imperial to metric weights.