pxt-calliope/docs/reference/input/light-level.md

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# Light Level
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Find the light level (how bright or dark it is) where you are.
The light level ``0`` means darkness and ``255`` means bright light.
The BBC micro:bit measures the light around it by using some of the
LEDs on the [LED screen](/device/screen).
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The first time you use it, this function will say ``0``.
After that, it will say the real light level.
This is because the light sensor (the part that can find the light level)
has to be turned on first.
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```sig
input.lightLevel();
```
### Returns
* a [Number](/reference/types/number) that means a light level from ``0`` (dark) to ``255`` (bright).
### Example: show light level
When you press button `B` on the microbit, this
program shows the light level
on the [LED screen](/device/screen).
```blocks
input.onButtonPressed(Button.B, () => {
let level = input.lightLevel()
basic.showNumber(level)
})
```
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### Example: chart light level
This program shows the light level with a [bar chart](/reference/led/plot-bar-graph) on the micro:bit screen.
If you carry the micro:bit around to different places with different light levels,
the bar chart will change.
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```blocks
basic.forever(() => {
led.plotBarGraph(input.lightLevel(), 255)
})
```
### Lessons
### See also
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[acceleration](/reference/input/acceleration), [compass-heading](/reference/input/compass-heading)
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