Drawing the correct Length of Line

I’ve got a question for you. Have a look at the illustration below, which line is the longest and which one is the shortest?

Hands up if you selected the second line as the longest and the first line as the shortest?

That’s certainly the way that it appears when we first glance at the picture. Having a closer inspection (below) reveals that all three lines are exactly the same length. The arrows at either end create an optical illusion that tricks us into believing that the second line is longer.

Imagine if we were making a drawing of these lines, if we drew the middle line longer we would have been wrong. Getting the length of every line correct compared to the lines around it is essential.

Whether you are drawing or painting, this is one of the 3 core fundamentals that you must learn to be able to successfully reproduce shapes in your artwork. This lesson is designed to show you how to easily compare lines for your drawings.

Here is a quick way that we can compare the length of lines (without measuring them).

In previous lessons we have looked at how to work out the direction of your lines, the amount of curve in a line and how to hold your pencil to press lightly. The first two lessons in particular deal with fundamental thought processes that are needed to be able to draw.

The third core process that we need to understand is the length of line. Remember that drawing is all about relationships, each line must work with the surrounding lines to make it resemble anything. This means that if the length of your lines aren’t working together you will have trouble making your shapes look correct.

What we need to do is to train our minds to be able to judge the length of any line compared to other lines around it. Today I’m going to share with you an easy method to compare line length.

Comparing line length may sound easy but it is often deceiving. If the lines are going in different directions or on opposite sides of the page it can be difficult to judge by eye. Optical illusions may also be taking effect, which can give the appearance of a line being longer simply because of the other lines around it.

The illustration below is the same 3 lines that we saw earlier but re-arranged differently on the page. See how hard it can be to judge the length, it certainly looks like the one on the left is much shorter.

drawing a line length optical illusion2

There are many ways that we can take a quick measurement of a line so that we can compare it against other lines. We don’t want to get too technical or mathematical about it, that just takes all the fun out of drawing and stops us from developing the skills to analyse length by eye. Here’s a quick way that we can do it without any math.

If you are copying from a drawing, painting or photo hold the bottom edge of your pencil at one end of the line that you want to copy. Use the tip of your fingernail along the shaft of the pencil to line up the other end of the line. Now you have a measurement from the end of the pencil to your fingernail that you can use to see how other lines compare. You can move your pencil around the page now to do comparisons and see if other lines are longer or shorter and roughly by how much. This can give you a clearer idea of the relationship of length of each line on the page.


Lets go back to our drawing of the book from your first lesson. Using the method above we can compare the length of lines to see which lines are the shortest and longest.We can see that the line (A) at the back of the book is quite a bit shorter than (B) the front of the book. Now check your own drawing to make sure that your lines have the same kind of relationship between lines A and B. Of course your line A is going to be a different length to the original drawing that you are copying from, but the idea is to compare A and B to see if they share the same size relationship with B being longer than A.

Drawing a book_lineLength_A-B

Now, Here is something real interesting…!

If we continue to compare other lines on the image we will notice that line B and line C are almost IDENTICAL in length. Who would have thought? Another optical illusion messing with our heads. Lucky that we checked, otherwise we might have drawn something different. Check your own drawing to see if you got it right.

Drawing a book_lineLength_B_C

Hopefully now we are beginning to understand how important the relationship of length is, even in apparently simple shapes. Be sure to do these checks of length and direction as often as you can while you are learning. Eventually with enough practice, your brain will develop the pathways to make this sort of judgement without measuring.

If you are drawing from real-life the same idea can be used by holding up your pencil in front of you and closing one eye to get a measurement in the same way with your fingernail and edge of pencil. You have probably seen cartoons of artists doing this and wondered what on earth they are doing.

But here’s the catch! Make sure that your arm is fully extended when making that measurement. Then you can move your pencil around to compare the length with other lines, but only with a fully extended arm. If your arm is bent when taking the measurement, you are likely to change the amount of arm-bend while doing your comparisons, which will bring your pencil closer or further from you. Perspective will then come into play and distort your results.

With practice, judging the lengths of lines of lines becomes easier. Over time we will come to do it automatically without measuring. As you are learning though, remember to check your lines as often as you can.

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