Drill 02Straight line between two points
How to draw straight lines freehand
Connect two dots. Find out whether your line curves or shakes — they are not the same problem.
Measures your line, not your drawingRuns on your deviceFree and unlimitedWant a real drawing checked?
Connect the two dots. One stroke, and go fast.
How it works
What it can name
The faults, drawn
A percentage on its own tells you nothing you did not already know. These are the separable problems the measurement identifies — each with a different fix, which is the whole reason for telling them apart. Every example below is a real stroke, generated by the same code that tests the engine.
Bow
One smooth curve. A committed movement that was never aimed — the fix is aiming, not slowing.
Tremor
What is left after the curve is removed. Caused by going slowly, so slowing down adds more.
Ratcheting
Drawn in short pushes. Every restart is a fresh chance to be a degree off.
Sideways miss
Straight, but not between the dots. The stroke was never aimed at the target.
Overshoot
Past the far dot. The movement was right and only its length was wrong.
Stopped short
Easing off on the approach — the same hesitation that curves a line.
Two tools, two questions
What this drill looks at
This drill · your line
Measures the stroke itself — how round, how straight, how evenly spaced, how far off the mark, and how the hand moved while it drew.
The number is arithmetic. The finding is not: which fault a set of measurements adds up to, and which fix it takes, is how drawing has been taught for a century. The instrument locates it; the teaching names it.
- Instant, exact, and the same answer every time
- Free and unlimited — it costs nothing to run
- Runs on your device; your drawings never leave it
- Cannot tell you whether the drawing works
Rate My Sketch · your drawing
Coach Luna checks a real drawing — a photo of your sketchbook or a screenshot — and marks the corrections onto the image itself.
She measures technique against what you were drawing: proportion versus your reference, shading, the joins. Never your creativity, your style or your subject — those are not hers to grade.
- Five technique scores, and the single fix to make first
- Three free every day, no account needed
- Generates nothing and never redraws your work
- Slower, and needs something real to look at
The two scores are different measurements and are not meant to agree. A circle can be geometrically excellent inside a drawing that does not work, and a drawing can work with shaky circles all through it. Use the drills to build the hand, use the critique to find out what the drawing needs next, and when you want the rest taught properly — construction, form, light, composition — that is what the Sketching Essentials course is for.
Is this the one you need?
Take all 7 drills and get a profile
About 5 minutes. It names your weakest skill and sends you to the drill that measures exactly that.
How the number is made
What the score actually measures
Straightness
peak of fitted parabola24% of the scoreThe one smooth, intentional curve in your line — measured from the chord between its own endpoints, so a line that starts offset is not counted twice.
Steadiness
rms( d − parabola )21% of the scoreWhat is left after that curve is subtracted. The most useful number here, because it separates a line that curves from a line that shakes — and those need opposite advice.
Aim
max |d| at either end26% of the scoreHow far to the side of the dots you finished. Sideways only: running past the far dot is a different skill.
Starting
|t_start|6% of the scoreWhere you began, along the line. Running up before the first dot is a different habit from overshooting the second one — it is a hand looking for confidence rather than a hand that could not stop — so the two ends are reported separately.
Stopping
|t_end − 1|8% of the scoreHow far past the far dot you ran, or how far short you stopped.
Hesitations
stops over 8, or the fraction of the drawing spent stopped — whichever is worse9% of the scoreHow many times the line changed its mind, and for how long. Counted two ways because a count alone cannot tell a 100ms rest from a full second: one long stop is read as the share of your drawing time that the pen spent still, and many short ones are read as a count. A pause leaves no mark, so this is the only part of the score that can see it at all.
One pass
furthest the pen fell back from its own high-water mark6% of the scoreWhether the line was drawn once. Everything else here reads the shape of your stroke, and going back over a line lays ink exactly where ink already is — same endpoints, same curve, same steadiness — so a stroke that reached the far dot, ran most of the way back along itself and came out again measured as a good line. It is one stroke, but it is two attempts.
Your stroke is measured against the two dots, never against a best-fit line through what you drew — fitting your own stroke would give a beautifully straight line drawn in the wrong direction a perfect score. Everything is divided by the distance between the dots, so the numbers mean the same thing on a phone and on a desktop. Every threshold, and the evidence behind it.
The technique
Draw a straighter line freehand
- 01
Fix both ends first
Look at the start dot, then the far dot, then back. Your eye needs to know the whole path before your hand starts.
- 02
Ghost the movement
Rehearse the stroke two or three times in the air above the surface, at the speed you intend to draw it.
- 03
Watch the target, not the tip
Keep your eye on the far dot for the whole stroke. Watching the pencil is what turns a movement into steering.
- 04
One pass, under a second
Draw it in a single continuous stroke and do not correct it. Judge afterwards.
Why the fix for a curve is the opposite of the fix for a shake
Both look like “not straight enough”, and the instinct for both is the same: slow down and be more careful. For one of them that is exactly wrong.
A smooth curve is a committed movement that was never aimed. Your arm is a set of hinges and every one of them sweeps an arc; if you start moving without a target, you get the arc your body wanted to make. The fix is aiming, not slowing — put your eye on the far dot and leave it there.
A shaky line is the opposite problem. Below a certain speed your brain stops running a rehearsed movement and starts steering by eye, correcting continuously against what it sees. Each correction is a visible wobble, and slowing down adds more of them. The fix is to go faster, accept that the first few will land badly, and let the accuracy come back.
A third case is worth naming because it feels the most responsible and does the most damage: drawing the line in a series of short pushes. Every restart is a fresh chance to be a degree off, and those errors accumulate rather than cancel. One committed stroke that misses is more useful than a chain of careful ones that wanders.
Ghosting, which is the actual technique
The method every drawing curriculum converges on has three parts, and the order is the whole point. Fix your two endpoints. Rehearse the movement in the air above the surface, several times, at the speed you intend to draw. Then drop down and execute it in one pass without correcting.
The rehearsal is doing something specific: it moves the planning out of the stroke. A line you are still deciding about while drawing it is a line being steered, and steering is what produces wobble. If the mark misses, the planning was wrong rather than the execution — so you ghost more next time, rather than drawing more slowly.
When you have got it
Five lines in a row above 85, drawn in under a second each, with no named fault. Then make it harder: draw the same line at a diagonal, then draw eight of them fanning out from one point. Ellipses are the natural next step — an ellipse is a line whose direction changes continuously, and it exposes whatever is left over.
Questions
My lines curve. Am I just drawing too fast?
Almost certainly the opposite. A smooth curve is a committed movement that was never aimed — your arm swept the arc it naturally makes. Slowing down does not straighten it; aiming at the far dot does.
What is the difference between a bow and a wobble here?
A bow is one smooth deviation, which we measure by fitting a parabola. A wobble is what remains after that parabola is subtracted. They score separately because a curve is a planning error and a shake is a speed problem.
Is it cheating to draw the line very fast?
No — that is the technique. Speed is what stops your eye steering the stroke. The drill also measures where you landed, so a fast line that misses both dots still scores badly.
Should I use my wrist, my elbow or my shoulder?
For a line this length, the elbow with a locked wrist, or the shoulder if you are working large. Short lines from the fingers are fine; the trouble starts when a long line is drawn with a short joint, which is what produces the arc.
Why does overshooting score better than missing sideways?
Because overshooting means the movement was right and only its length was wrong, which is a much smaller correction. Landing to the side means the stroke was never aimed at the target at all.
Does this work with a mouse?
The aiming and stopping measurements do, exactly. Straightness and steadiness are partly about the device — a trackpad in particular forces a re-grip mid-stroke — so compare your scores against your own earlier attempts on the same hardware.
Why is there no eraser?
Because the line you drew is the measurement. Erasing the wobbly middle and redrawing it would be editing the evidence rather than improving your hand. Undo drops the stroke and you can go again as often as you like.
Is my drawing uploaded?
No. The whole calculation runs in JavaScript in your browser. No image is sent anywhere and no model is involved.
Next drill
Ellipse inside a plane
Draw one ellipse that fills the box. Two laps, without lifting.
Drew something real?
Rate My Sketch
These drills measure geometry. For a drawing with a subject in it, Luna scores five technique dimensions and marks the corrections on your image.