How to Draw an Open Mouth
Learning how to draw an open mouth is really about understanding structure, not just copying lips and teeth.
Once you know the basic anatomy and shape relationships, you can draw expressions that look natural from almost any angle.
An open mouth can show speaking, shouting, laughing, surprise, or pain, which makes it one of the most expressive features in portrait drawing.
The challenge is keeping the mouth believable while the lips, teeth, tongue, and jaw all shift together.
Start With the Basic Mouth Shape
Before adding details, block in the mouth as a simple opening.
Think of it as a stretched oval, a rounded triangle, or a wedge depending on the expression and angle of the head.
Keep the opening smaller than you think at first.
In many drawings, beginners make the mouth cavity too large, which makes the face look distorted or overly dramatic.
- Sketch the center line of the face first.
- Place the mouth below the nose and above the chin.
- Mark the corners of the mouth lightly.
- Draw the opening as a simplified shape before adding lips or teeth.
Understand the Anatomy Before Adding Details
The mouth is not just a hole.
It is formed by the upper lip, lower lip, oral cavity, teeth, gums, tongue, and the surrounding muscles of the face, including the orbicularis oris.
The upper lip often overlaps the teeth more than the lower lip does.
The lower lip usually has more volume and catches more light, while the upper lip tends to sit in shadow.
For realism, remember that the teeth are not flat, bright rectangles.
They follow the curve of the jaw and sit inside the mouth, partially hidden by the lips.
What should be visible in an open mouth?
That depends on the expression and angle.
A relaxed speaking mouth may show only a hint of teeth, while a wide yawn may reveal the tongue, upper palate, and deeper shadow inside the oral cavity.
- Closed-to-partially open mouth: lips separate slightly, little or no teeth visible.
- Speaking mouth: teeth may show briefly, with moderate lip movement.
- Wide open mouth: teeth, tongue, and inner shadows are more visible.
Draw the Lips First, Then the Opening
Many artists get better results by drawing the lips as forms surrounding the opening instead of outlining teeth first.
This helps preserve the volume of the face.
The upper lip usually creates a shallow M-like shape, though it can vary by expression, age, and anatomy.
The lower lip is often fuller and curves outward, creating a rounded base for the opening.
Use the lip line to define the expression.
A relaxed mouth has smoother curves, while a tense or shocked expression may pull the corners downward or stretch the lips tighter.
Place the Teeth Carefully
Teeth are one of the most overdrawn parts of an open mouth.
In many cases, you do not need to draw every tooth.
Suggest the forms with grouped shapes rather than outlining each one clearly.
The top row of teeth is usually more visible than the bottom row because the upper jaw overlaps the lower jaw.
The front teeth are broader, and the side teeth gradually angle away in perspective.
- Keep tooth edges soft, not razor sharp.
- Show separation with subtle value changes instead of heavy outlines.
- Make front teeth slightly larger than side teeth to reinforce perspective.
- Avoid drawing a full grid of equal-sized teeth.
Shape the Tongue and Mouth Cavity
The tongue is a major form inside the mouth, especially in laughing, yelling, or speaking poses.
It is typically a rounded shape that sits lower in the oral cavity and follows the perspective of the jaw.
The mouth cavity itself should usually be the darkest area in the drawing.
This darkness helps separate the lips from the interior and makes the mouth read as deep space rather than a flat shape.
To keep the drawing believable, vary the darkness.
The far back of the mouth is darkest, while the tongue and inner lips may catch more reflected light.
Use Perspective to Match the Head Angle
The open mouth must follow the angle of the head.
A face viewed from below will show more of the bottom lip and lower teeth, while a face viewed from above may hide the lower lip and compress the mouth opening.
If the head turns sideways, the mouth also turns in perspective.
The far corner of the mouth will appear shorter and less visible, and the lips will wrap around the curve of the face.
How do you keep the mouth aligned on a turning face?
Start with a center line for the face, then position the mouth along that axis.
The mouth should follow the same tilt as the eyes, nose, and jaw so the expression feels attached to the head.
- Use construction lines to map the face plane.
- Think of the mouth as wrapping around a cylinder.
- Shorten the far side of the lips in three-quarter view.
- Shift the opening slightly with the head’s rotation.
Shade for Depth and Form
Shading is what makes an open mouth feel three-dimensional.
The key is to separate the planes of the lips and the cavity using value, not just outlines.
Cast shadows usually appear under the upper lip and inside the mouth opening.
The lower lip often catches more light, especially along its outer edge, which helps it stand out from the chin.
Use softer shading for skin and sharper contrast only where the mouth cavity needs to recede.
Hard lines around the lips can make the drawing look stiff, so vary edge quality to match the expression.
Common Mistakes When Drawing an Open Mouth
Even experienced artists can simplify the mouth too much or over-detail it.
Watching for the most common errors will help your drawings look more convincing.
- Making the mouth too large: the opening should usually stay connected to the face structure.
- Outlining every tooth: this makes the mouth look artificial.
- Ignoring the lips: the lips define the opening and expression.
- Using one flat shadow: the mouth needs layered values for depth.
- Forgetting perspective: the teeth and lips must match the head angle.
Practice Different Expressions
Once you understand how to draw an open mouth, practice several expressions to build flexibility.
Each expression changes the lip tension, tooth visibility, and shape of the cavity.
- Speech: subtle opening, natural lip motion, partial tooth visibility.
- Laughter: wider upper lip lift, visible upper teeth, curved cheeks.
- Shout: stretched mouth opening, darker cavity, strong jaw drop.
- Surprise: rounder opening, lifted upper lip, less tension in the corners.
Build Accuracy With Reference and Observation
Reference photos and live observation are valuable because mouths change constantly with age, emotion, and lighting.
A child’s mouth, an older adult’s mouth, and a face in profile all behave differently.
Study how the lips compress, how teeth disappear behind the lips, and how the mouth cavity changes shape under different expressions.
The more you observe real mouths, the easier it becomes to simplify them accurately in your own style.
For strong results, combine anatomy knowledge with quick gesture sketches, then refine the final drawing only after the structure looks correct.