In this post I cover one of the drawing basics you must know from the start.
If you’ve ever watched someone drawing from life, you’ve probably seen them hold a pencil up at arm’s length and squint at the subject.
It can look a bit odd if you don’t know what’s going on.
They’re not waving the pencil around for effect. They’re using it as a simple measuring tool.
Artists use a pencil to compare heights, check angles, test alignments, and judge proportions. It’s a quick way to stop guessing and start drawing what you can see.
The first use is probably the most common, measuring proportions.
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Measuring Basic Proportions
One of the main reasons artists hold up a pencil is to compare sizes.
The pencil becomes a quick measuring stick.
In this example I’m checking the two visible sides of the same building. I hold the pencil vertically at arm’s length and line it up against the left wall. My elbow stays locked and the pencil stays the same distance from my eye.
Then I shift my whole arm across and compare the right side of the building without changing anything.
That’s the important part.
If you bend your arm, tilt the pencil, or move your head, the measurement changes and the comparison becomes useless.
Because both measurements are taken under the same conditions, I can see straight away that left side appears shorter than the right side..
That tells me something important about the perspective.
If my sketch shows both sides the same height, I know I’ve made a mistake.
You don’t need exact numbers. You’re looking for relationships.
Is one side taller/longer or noticeably smaller/shorter?
These quick comparisons help you spot errors before you’ve committed too much detail to the drawing.
Finding True Angles
A pencil is useful for more than measuring lengths. You can use it to judge angles too.
In these examples I’m comparing the two rooflines of the building.
I hold the pencil at arm’s length and rotate it until it matches the angle of one roof slope. My arm stays rigid and the pencil becomes a movable reference line.
Once I’ve found the angle, I keep my grip and compare it against the opposite side.
Straight away I can see that the two slopes are different.
That matters.
If I draw both rooflines at the same angle, the building will look wrong, even if the proportions are accurate.
This is an easy mistake to make because your brain likes to simplify shapes. You know it’s a roof, so you tend to invent a neat, symmetrical angle instead of drawing what you can see.
Using a pencil slows you down and forces you to double check.
You don’t need to think in degrees. You’re only asking a simple question.
Is this angle steeper, higher, lower, or roughly the same as the last one?
Those small comparisons make a big difference to the accuracy of your sketch.
Checking For Alignment
You can use a pencil to check alignment as well.
In this example I’ve held the pencil horizontally across the top of the lamppost.
Straight away I can see that the top of the lamppost lines up exactly with the corner of the building.
That’s useful information.
Without checking, I might have guessed that the building corner sits higher or lower and drawn it incorrectly.
This is a quick way to compare positions across your subject.
You can use the pencil horizontally to check levels, or vertically like a plumb line to see what sits directly above, below, or beside something else.
This enables you to cross reference the placing of features more accurately. Are the windows aligned? Have you placed the chimneys in the right position?
These small checks stop objects drifting out of place.
Your eye can be surprisingly unreliable when you’re staring at a complicated scene. A quick alignment check removes the guesswork.
Measuring Negative Spaces
Artists don’t only measure objects. You can measure the spaces between them as well.
In this example I’ve shaded the negative space between the lamppost and the building.
First, I use my thumb on the pencil to measure the gap from the top of the lamppost to the corner of the building. That becomes a new unit of measurement.
Now I can compare everything against that unit.
How wide is the negative space compared to the height of the building corner?
How tall is the gap compared to the lamppost?
Does the shape narrow, widen, or stay fairly even?
These empty shapes often reveal mistakes that are easy to miss when you’re focused on drawing the objects themselves.
Your brain knows what a building looks like. It knows what a lamppost looks like.
But it doesn’t recognize the awkward shape of the air trapped between them.
That’s useful.
Because you have fewer assumptions, you’re more likely to draw the space honestly.
If the negative space in your sketch doesn’t match what you see, something is out of place, even if you can’t immediately tell whether it’s the building, the lamppost, or both.
Why Artists Measure in the First Place
All of these methods have one thing in common.
They stop you drawing what you think you see.
Your brain likes shortcuts. It recognizes a building, a face, or a tree and quickly fills in the gaps.
That’s useful in everyday life, but it can wreck a drawing.
You assume the roof angle is symmetrical.
You assume two windows are level.
You assume the gap between objects is smaller or larger than it really is.
Using a pencil forces you to slow down and check.
Instead of trusting your memory or instincts, you compare lengths, angles, alignments, and negative spaces against what is actually in front of you.
You don’t need to measure everything.
Most experienced artists don’t.
But when something looks wrong and you can’t see why, a few quick checks with a pencil can expose the problem very quickly.
A few practical rules matter:
• Lock your elbow. Always measure with your arm fully extended.
• Keep your position fixed. Move your head and the measurement changes.
• Close one eye. Two eyes give slightly different viewpoints.
• Use the same grip and distance every time.
That’s why you’ll often see artists holding a pencil at arm’s length while drawing from life.
It’s a simple tool for seeing more accurately. Tried and tested for centuries.
Drawing Basics: Final Thoughts
Learning to observe and measure accurately is one of the foundations of good drawing.
Most beginners want better shading, more realism, or cleaner detail, but those things sit on top of the basics. If your proportions, angles, and relationships are off, the drawing will struggle no matter how polished the finish looks.
There are a few core skills you need to get to grips with before your drawings start matching what you see.
If you want help with that, I recommend Stan Prokopenko’s Drawing Basics course. He covers the fundamentals clearly, demonstrates them properly, and teaches the kind of practical drawing skills that can make a noticeable difference to your work.
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