specific temperature vs "medium heat" on an induction cooker?

Low, Medium, Medium-low, Medium-high and High are weasel-words so that manufacturers/recipe writers cannot be blamed for misuse of equipment/recipes, so a specific temperature range for medium heat cannot be given for just any cooker out there.

For an oven, I use as a rule of thumb: 50-100°C (100-200°F) Low heat, 100-150°C (200-300°F) Medium low, 150-200°C (300-400°F) Medium high and 200+°C (400+°F) for High...

For an induction cooker, my personal rule of thumb would be:

• Low, Medium, High: 1/3 strength, 2/3 and just below boost respectively
• Low, Medium-low, Medium-high and High: 1/4, 1/2, 3/4 and just below boost respectively

As I've seen induction cookers go from "?" to "15" (excluding boost), above rule of thumb should be taken with a shovel of salt...

There is no specific temperature for "medium heat" on any cooker at all.

I know that many induction cookers come with a display which shows some kind of "temperature" setting instead of just a number. This is a useless feature, and does not correspond to any real temperature anywhere.

First, if they try to implement it with a firm amount of modulation (= percentage of time the coil is on), it will be the same thing as the "wattage" setting, only translated to some other number. The problem is that depending on the size of the pan, the amount of food, and many other variables, you will end up with different pan temperatures at the same setting.

Second, I think there are models which try to be more clever, and they hold a constant temperature at a sensor, changing the modulation as needed. The problem with this approach is that the sensor is somewhere below the glass plate, far far away from your pan. So the real temperature in the pan is not at all the one shown in the sensor, and the shape of the pan bottom also means that, with different pans, you will get different in-pan temperatures for the same sensor reading.

The best you can do is to forget that this setting is there, and to use the induction cooker as any other cooker, that is, reading the different "temperatures" or "wattages" as a simple ordinal scale without any meaning between the number, similar to the "1 --- 6" settings on a standard hob. As usual, you will have to learn to recognize a medium heat based on the way your food cooks, and for temperature critical applications, to use an infrared thermometer.

To expand on what's already been said -- even if you use 'medium' heat on a given burner, the size of the pan vs. size of the burner, plus the maximum heat output (BTU) of the burner makes a significant contribution to the resulting temperature of the pan.

Also, you have to consider what's in the pan -- a dry pan is going to heat up more than something with lots of moisture, as you both have thermal mass to absorb heat and the possibility of evaporative cooling.

You're better off going with other indicators of temperature like 'shimmering oil' if the recipe mentions something to that effect.