How to Make a Height Comparison Chart to Scale

An accurate height comparison chart needs three things: one unit for every measurement, one scale for every figure, and one shared ground line. Decorative silhouettes are optional. Two plain bars can communicate a height difference more faithfully than detailed figures that have been resized independently.

Here is a complete example. To draw people who are 160 cm and 180 cm tall in a 400-pixel-high plotting area, allow the vertical axis to reach 200 cm. Each centimeter then occupies 2 pixels. The two figures should be 320 and 360 pixels tall, aligned at their feet. Their 20 cm difference becomes a 40-pixel gap between their tops.

You can enter those heights in the height comparison tool, or use the method below in a spreadsheet, drawing app, classroom worksheet, or presentation. The examples are calculated illustrations, not measurements of real people.

Start with measurements you can explain

Make a small input table before drawing anything. Include a name or neutral label, a height, a unit, and where the number came from. A measured barefoot height, a person’s stated height, and an estimate from a photograph are different kinds of evidence. Label them accordingly instead of giving every figure the same apparent certainty.

For fictional characters, note which version or source you are using. For people, do not estimate a missing measurement from head size or shoulder position. Those features vary, and an image adds camera perspective to the problem. Our guide to comparing heights from a photo explains when a photograph is unsuitable for measurement.

For a private family chart, labels such as A and B are enough. You do not need to publish names, ages, or personal photographs to make the comparison useful.

Convert mixed units before choosing the scale

Use centimeters throughout the calculation, even if you display feet and inches beside the finished figures. An inch is exactly 2.54 cm, according to NIST’s length-unit reference. Convert feet to inches first:

height in centimeters = ((feet × 12) + inches) × 2.54

For example, 5 ft 4 in is 64 inches, or 162.56 cm. It is not 5.4 feet: decimal feet and feet-plus-inches are different formats. A 5.4-foot value is 164.592 cm, which would introduce a little over 2 cm of error in this example.

Keep the unrounded converted value for plotting. You may show 162.6 cm in a label, but there is no advantage in rounding to 163 cm before calculating the figure’s size. The height converter handles the unit arithmetic if you want to check your inputs.

Calculate a single scale for the entire chart

First separate the plotting area from the whole image. A 600-pixel-tall image might reserve 80 pixels for a title and 40 pixels for labels, leaving 480 pixels for the height axis. Use that 480-pixel area in the calculation.

Choose an axis maximum above the tallest figure. For a group whose tallest member is 187.96 cm, 200 cm is a convenient maximum. It leaves room above the figure and makes the tick labels easy to read.

pixels per centimeter = plotting-area height ÷ axis maximum in centimeters

figure height in pixels = person’s height in centimeters × pixels per centimeter

With a 480-pixel plotting area and a 200 cm axis, the scale is 2.4 pixels per centimeter:

A drawing app may round those dimensions to whole pixels. At this scale, one pixel represents about 0.417 cm, so whole-pixel rounding is sufficient for a general illustration. It is not a reason to claim that the underlying measurements are accurate to a fraction of a centimeter.

Align the feet, not the centers

Put every figure’s feet on the same horizontal baseline. If your drawing software centers images vertically, a shorter figure may float above the floor, making the visual comparison wrong even when its pixel height is correct.

In a coordinate system where vertical positions increase downward, calculate the top edge this way:

top position = baseline position − drawn height

If the baseline is at y = 520, figure B’s 420-pixel height gives a top position of y = 100. Figure C starts at approximately y = 68.896. Their feet still end at y = 520.

Also check the visible artwork inside each image. Transparent space above a head or below the feet counts toward an image element’s dimensions but is not part of the person’s stature. Crop unused margins or use simple rectangles when you cannot identify consistent top and bottom landmarks. Keep the original width-to-height ratio of any silhouette; stretching only its height can distort the body shape.

Make the difference readable without exaggerating it

Use an axis that starts at zero for a full-body comparison. Cropping the bottom of the chart can make a small difference look disproportionately large. If you need a close-up of the top edges, label it as a detail view and retain the full chart nearby.

For A and C above, the height difference is 25.4 cm, exactly 10 inches. On this chart it becomes 60.96 pixels. A short bracket or a text label reading “25.4 cm difference” can be clearer than expecting a reader to count grid lines.

Avoid adding many tiny ticks. On a small phone screen, labels every 20 cm may be more legible than labels every 5 cm. Preserve the exact values in text even when the visual grid is sparse. For the subtraction steps, see how to calculate height difference.

Adapt the chart for a phone screen

A chart that fits on a desktop can become unreadable when several figures are squeezed into a narrow screen. You have two useful choices:

• Show a smaller group at a time while keeping the same vertical scale between views.
• Allow horizontal scrolling and keep labels close to their figures.

Do not resize every figure to fill its own card. If a 160 cm figure and a 190 cm figure both fill identical cards, the chart loses its shared scale. The same problem occurs when separate screenshots are resized independently before being placed side by side.

If the whole chart is reduced uniformly, the proportions remain correct. The text may still become too small, so include a plain-text summary below it, such as “A: 162.56 cm; B: 175 cm; C: 187.96 cm.” Use both labels and colors so the meaning does not depend on distinguishing colors alone.

Print a chart at a physical scale

A printed chart uses a different instruction from a screen chart. A scale of 1:10 means every 10 cm of real height becomes 1 cm on paper. A 180 cm person should therefore appear 18 cm tall; a 160 cm person should appear 16 cm tall.

Add a calibration line labeled “This line should measure 5 cm on the printed page.” Print without automatic enlargement or “fit to page,” then measure the line with a ruler. If it measures 4.5 cm, the print has been reduced to 90% of the intended size. The figures’ relative heights remain comparable, but the stated physical scale is no longer accurate.

Do not use an ordinary screen image as a ruler against a person’s body. Display zoom and device scaling affect physical size. The W3C explanation of CSS units distinguishes screen rendering from physical print dimensions. A chart can be proportionally correct without being life-size on your display.

Check the finished chart with two quick calculations

First check a ratio. For the simple 160 cm and 180 cm example, the shorter figure must be 160 ÷ 180, or about 88.89%, of the taller figure’s height. If the taller figure is 360 pixels, the shorter must be 320 pixels. This check catches independent resizing.

Then check the difference. The numerical height gap multiplied by the shared scale must match the gap between the top edges. At 2 pixels per centimeter, a 20 cm difference must occupy 40 pixels. If the ratio is correct but the top-edge gap is wrong, look for different baselines or transparent image margins.

Before sharing, confirm that the units are visible, the measurement source or estimate is identified, the baseline is consistent, and the labels remain readable at the final size. These checks matter more than adding decorative detail. The finished chart should let a reader understand both the comparison and its limits without guessing how it was made.