There are a bunch of smartphone apps out there you can use to convert an image to a pencil drawing. However, if you want to look like a pro and want to learn image editing more seriously I suggest you to lessen the consumption of smartphone app use.
Converting an image to a pencil drawing is straightforward in GIMP. You just need to understand the use of basic settings like saturation and color level.
GIMP has lots of layer modes you can choose from. We are going to take advantage of this feature to turn an image into a pencil drawing. There are three layers we are going to use.
- Step 1: Open image and duplicate its layer to three
First and foremost, launch GIMP on your computer and open an image you want to convert to a pencil drawing. Then, duplicate the layer of the image to three.

- Step 2: Set the saturation of layer 1
Once you duplicate the layer to three, now it's time to work with each layer. Firstly, you need to work with layer 1 to set its saturation.
So, select layer 1 and go to Colors -> Hue-Saturations.

Set the saturation to the lowest value (-100) and you will get your image turned to black and white.

Change the mode to Saturation.

- Step 3: Apply the Gaussian Blur effect to layer 2
Now, switch to layer 2 to apply the Gaussian Blur filter to this layer. Before applying the filter, change the mode of this layer to Dodge.

Go to Colors -> Invert

Now, you can go to Filters -> Blur -> Gaussian Blur to apply the filter. Don't make your image too blurry. Changing the value to 10 is enough.

- Step 4: Set the color levels of layer 3
Switch to layer 3 to set its color levels. To do so, go to Colors -> Levels. Set the Input Levels by sliding the selector.

That's it! The following is the example of the result of this tutorial.
