This post is about the thinking behind my Microwave Cooking Time Conversion tool.
There exists a need to convert microwave cooking times based on various power levels (watts). This is because a recipe is given for one power level, which isn’t the same as your microwave.
Some information providers offer charts to find equivalent cooking times per numerous watt levels.
That didn’t seem right to me. The amount of data gets quite large. And often it lacks precision because the provider is selective in which watt-levels it offers. (For example, showing 700w but not 750w).
A calculator is what is called for. We ascertain the formula.
(Recipe Wattage / Your Microwave Wattage) * Cooking Time in Seconds
Inputs
Setting the 2 watt-levels
We believe a slider is the ideal input for wattage level. We had learned that the range of common watt levels goes from 500w to 1500w. Using the jQuery UI slider, we can set increments of 50. For recipe wattage, we default to 700 (most common for package’s recipes). For our mike’s wattage, default is 950.

Setting the Cooking Time
A microwave is a system of buttons. People are accustomed to using the number pad to enter time. Why not use that same interface for our calculator? This context would match up with the real-life context.
We found a cool working microwave simulator and re-purposed it for our needs, namely, to enter values that set the clock. Then, instead of a Start button, we make a “Convert” button. When the user clicks it, the calculation is done. (First step being to convert number input into “seconds.” )

Displaying the Converted Time
Our calculation complete, we need to format it back into “minutes:seconds” which is easy enough. But where to display the converted time? We decide to simply stay put, and print it out in the same Clock space. So, the microwave interface remains. All we do is give a different background color to denote the conversion.

Why it Works Well
Using a microwave simulator might seem a case where excessive design impedes efficiency. But that is not the case here. Rather, our design is efficient because it benefits from the nature of the real-life input, which is intuitive and a fast (and fun) way to enter values. Press press press.
Our design is pleasant, familiar, and effective.
Compare it to The Omni Calculator or the Conversion Charts.