# I am very new to Node Red, have a question about Sliders
**URL:** https://discourse.nodered.org/t/i-am-very-new-to-node-red-have-a-question-about-sliders/60853
**Category:** General
**Created:** [6 April 2022 00:08 UTC](https://discourse.nodered.org/t/i-am-very-new-to-node-red-have-a-question-about-sliders/60853 "2022-04-06T00:08:55Z")
**Posts on this page:** 4
**Page:** 1
### Author:  [@mikhael47](https://discourse.nodered.org/u/mikhael47)
#### Post date: [6 April 2022 00:08 UTC](https://discourse.nodered.org/t/i-am-very-new-to-node-red-have-a-question-about-sliders/60853/1 "2022-04-06T00:08:55Z")
I am looking to take a slider and use it to adjust the value of the output of a dht22 humidity sensor.
The Humidity value is stored in msg.humidity and I would like the interface to allow me to "calibrate" the humidity by the amount selected on the slider.
I already have the humidity level triggering a relay
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### Author:  [@craigcurtin](https://discourse.nodered.org/u/craigcurtin)
#### Post date: [6 April 2022 02:57 UTC](https://discourse.nodered.org/t/i-am-very-new-to-node-red-have-a-question-about-sliders/60853/2 "2022-04-06T02:57:59Z")
So will this be a "standing" calibration ? i.e. the same value used to offset the return value from the DHt22 everytime NR is restarted - or would you expect the user to do another calibration after each restart ?
If you want to keep the calibration factor - then take the output of the slider - feed it into a change node and store this in a flow context variable (make sure you have persistent storage setup)
Then reference that flow variable each time you restart node red and/or take a Humidity reading and use that in your calculation
Craig
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### Author:  [@mikhael47](https://discourse.nodered.org/u/mikhael47)
#### Post date: [6 April 2022 12:56 UTC](https://discourse.nodered.org/t/i-am-very-new-to-node-red-have-a-question-about-sliders/60853/3 "2022-04-06T12:56:24Z")
My initial prototype does not require "standing" calibration. Once I have the code built, I'll be moving on to storing the data in a db. That being said, I can just store this in a flat file and use that as a flow variable.
Thanks for your suggestion. I appreciate it.
Mike
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### Author:  [@system](https://discourse.nodered.org/u/system)
#### Post date: [5 June 2022 12:56 UTC](https://discourse.nodered.org/t/i-am-very-new-to-node-red-have-a-question-about-sliders/60853/4 "2022-06-05T12:56:42Z")
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