5.1 Human figure proportions and ratios

Human figure proportions are the size relationships between the parts of the body and the whole figure, usually measured using the height of the head as a unit. Interior designers draw human figures in sketches, elevations, sections and perspectives to show scale, to show how people use a space and to make drawings feel lifelike, so figures must be correctly proportioned or the whole drawing will look wrong in size. Using standard ratios lets a designer draw believable figures quickly and at any scale, without measuring a real person each time. Example: when preparing a section drawing of a hotel's double-height lobby, a designer adds standing figures drawn eight heads tall, so the client immediately understands the height of the space and the size of the reception desk.

The head as a unit of measurement

The head height, from the top of the skull to the bottom of the chin, is the standard unit for measuring the figure. An average adult is about 7 to 7.5 heads tall, while artists and designers often use 8 heads for an idealised, elegant figure that reads well in presentation drawings. Taller "heroic" figures of 8.5 to 9 heads are used in fashion and illustration but look exaggerated in interior drawings.

Landmarks of an eight-head adult figure

Key proportional relationships

• Midpoint of the body: The crotch is at about half the total height.
• Arm span: The distance from fingertip to fingertip with arms stretched out equals the height.
• Elbows: Fall at about waist level when the arms hang down.
• Wrists and fingertips: The wrists reach the crotch line and the fingertips reach mid-thigh.
• Hand size: A hand is about the length of the face, from chin to hairline.
• Foot length: A foot is about the length of the forearm, or slightly longer than one head.
• Shoulder width: About two head lengths in men and slightly less in women.

Differences between male and female proportions

Proportions at different ages

Steps for drawing a proportioned standing figure

1. Decide the figure height: Set the total height to suit the drawing scale.
2. Divide into head units: Draw a vertical line and divide it into eight equal parts.
3. Draw the head: Sketch an oval in the top unit.
4. Mark the landmarks: Mark chest, navel, crotch, knees and feet on the correct head lines.
5. Set the widths: Mark shoulder and hip widths using head units.
6. Block in the body: Draw simple shapes for the torso, pelvis, arms and legs.
7. Check the relationships: Confirm elbows at the waist, wrists at the crotch and fingertips at mid-thigh.
8. Refine the outline: Add clothing and details while keeping the proportions.

Common proportion mistakes

• Head too large: Makes adults look like children.
• Legs too short: The crotch drawn above the halfway point makes the figure look stunted.
• Arms too short: Wrists that do not reach the crotch line look unnatural.
• Feet too small: Small feet make figures look unstable.
• Inconsistent figures: Figures in the same drawing drawn to different proportions confuse the scale.

Worked example: drawing a figure to scale

Drawn height = actual height ÷ scale

Head unit = drawn height ÷ number of heads

A designer adds a 1.75 m tall standing figure to a 1:50 elevation of a bank's customer hall and uses an eight-head figure.

Drawn height = 1,750 ÷ 50 = 35 mm

Head unit = 35 ÷ 8 ≈ 4.4 mm