You can't, at least not without an actual temp sensor to calibrate it with. With no external reference , no amount of code is going to help you. It's a thermister. It was never designed to measure temperature. It was designed to measure changes in heat. If you want to measure temperature., buy a temperature sensor. That's about as simple as I can make it for you. If you think you're going to measure temperature without a calibration reference then your mistaken. If you can put it in ice water and measure it and then put it in boiling water then you have two references 0 degree Celsius and 100 degrees celsius. It will never be accurate for measuring temperature, period end of story.