3 Tricks for Getting Accurate Proportions While Sketching

January 18, 2022  /  by Megan Biffert

Open sketchbook showing a watercolor sketch of mountains

Let’s admit it: getting accurate proportions and angles while you sketch can be an absolute headache.

Have you ever done that thing where you draw and erase a line 11 times and still don’t have it right? I definitely have!

It can be very discouraging. However, I’ve come to find that using these three tricks solves all of my accuracy problems while sketching! Without giving me a headache. 🙂

What’s extra nice is that they don’t require any extra tools or an engineering degree. Just your pen and a little bit of patience. You can use them on any kind of sketch subject, whether you are drawing from a reference photo or sitting outside sketching from life.

So here they are! I hope they bring more ease and enjoyment – as well as accuracy – to your sketching.

1. “Map” Angles With Your Pen


This is a super handy trick for checking angles and perspective without having to do a lot of measuring! So if you are trying to accurately sketch the angle of a line, try this.


Hold out your pen in front of you and line it up so that it is parallel with the line you are trying to draw (see picture on the left above).

Then, without moving that hand, move your sketchbook to behind your pen and “map” that angle onto the page (see picture on the right above).

And there you go! An accurate angle! You can either lightly sketch the line on the page first, then use this method to check that the angle is correct. Or you can first “map” the line onto the page and then draw it.

2. Use Your Pen to Measure & Check Proportions

Accurate proportions can make or break a sketch! You don’t need them to be perfect, but you do want your measurements to be fairly correct so that your subject is recognizable.

Good news! You don’t need a ruler and professional-level math skills to accomplish this. You already have a handy instrument: your pen!


Hold out your pen in front of you and use your finger on the pen to mark the width or length of a certain line or edge on your subject. Then move your arm (still at the same length from you!) and hold up your pen in front of another line or edge, and see how that measurement compares with the first one. This way you can compare relative proportions and then sketch them accurately.

For example, if you watch the video above, you will see that the width of the left-hand wall of the building is half a pen length, and that the height is two half-pen lengths (or a full pen length). So that shows that the width of the left wall is roughly one half of the building’s height. It tells me that when I draw the height of the building, I need to make sure it is twice as tall as the width of the left-hand wall.

Do this trick throughout your sketch as you draw the basic outlines, and soon you will have accurate proportions without needing to do math or use a ruler!

3. Use Reference Points


Do you ever struggle with how to get all of the lines and corners in the correct place? Well, using reference points while you sketch will save you the headache of figuring out where to start and end a line!


In your sketch, start with a line you’ve already drawn (see Line A) as your main point of reference. It needs to be one that you aren’t going to change and you already know is accurate. I often use a strong corner of a building, like the one shown in the photo. That’s the first line I would draw in my sketch.

Then, lightly draw the line you want to sketch next, like Line B. You can use the pen measuring method shared earlier in this post to know how far away this line needs to be from Line A. But you don’t necessarily know where to end it or how tall it is.

What we want to know is where the top of Line B is relative to Line A. So here’s what you do next.



Look at your subject (if you are sketching live) or at your reference photo. Put the tip of your pen at the top of that line where it ends (shown by the circled dot on Line B in the photo) then drag your pencil across the scene to where it intersects that strong corner line (shown by the dot on Line A). 

You now have a reference point. You know the height of Line B relative to Line A. And since you’ve already drawn Line A, you can use this reference point to decide where to end Line B!


Now you can go back to your sketch, place the tip of your pen on Line A where that reference point approximately is, then lightly drag it horizontally across the paper until you intersect Line B. And that is where Line B ends. 

Bonus: You now can draw the roof line accurately as well! Just connect the top of Line B to the top of Line A. This is the magic of reference points; they all interconnect and help you quickly AND accurately draw the main lines of a subject.

If you use reference points like this throughout your sketch, it will save you a lot of energy and effort in figuring out where lines stop and start!

Did you find these helpful? Which trick do you think you’ll use the most? Comment below, I’d love to hear!

About Megan

Megan Biffert is the owner and creator behind Hey There Chickadee. Ink and watercolor art her go-to art mediums. She not only sketches and paints on a regular basis, but also offers classes and inspiration to those who want to create their own art. Her greatest delight in operating Hey There Chickadee is seeing others discover joy, creativity, and community through drawing and painting!

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