# How does the calibrateLight block work
**URL:** https://forum.makecode.com/t/how-does-the-calibratelight-block-work/596
**Category:** EV3
**Created:** [October 9, 2019, 9:56am UTC](https://forum.makecode.com/t/how-does-the-calibratelight-block-work/596 "2019-10-09T09:56:46Z")
**Posts on this page:** 2
**Page:** 1
### Author:  [@mkrdroid](https://forum.makecode.com/u/mkrdroid)
#### Post date: [October 9, 2019, 9:56am UTC](https://forum.makecode.com/t/how-does-the-calibratelight-block-work/596/1 "2019-10-09T09:56:46Z")
I’m unclear how to the calibrateLight block works. How does it know the sensor is over the dark or light area? Does it sample several times a second and find the min and max reflection in a given time or until the program ends. Are the calibration values stored or do I run the procedure every time? Also, if there are two sensors do we calibrate them individually.
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### Author:  [@peli](https://forum.makecode.com/u/peli)
#### Post date: [October 9, 2019, 3:11pm UTC](https://forum.makecode.com/t/how-does-the-calibratelight-block-work/596/2 "2019-10-09T15:11:12Z")
For reference, here is the impl: [https://github.com/microsoft/pxt-ev3/blob/master/libs/color-sensor/color.ts#L333](https://github.com/microsoft/pxt-ev3/blob/master/libs/color-sensor/color.ts#L333)
It resets the sensor, then collects readings until it does not change anymore, compute min/max range and applies a threshold. It does not store the results yet but it’s an excellent suggestion.
2 sensors is not supported. You would have to write your own sequence. I guess when we store the data things would be easier as well.