To find the difference between two heights, put them in the same unit, subtract the smaller from the larger, then convert the difference into whatever unit you want to report. This avoids mistakes such as subtracting “feet” and “inches” separately as if they were decimals.
For example, 5 ft 7 in and 6 ft 0 in differ by exactly 5 inches, or 12.7 cm. The first height is 67 inches; the second is 72 inches. The difference is 72 − 67 = 5 inches, and 5 × 2.54 = 12.7 cm. The inch is defined as exactly 2.54 cm; the factor is given in NIST’s SI conversion guide.
If you would rather skip the arithmetic, enter both values in the height difference calculator. The rest of this guide shows what the calculator is doing so you can check a result, handle mixed units, and choose sensible rounding.
The two formulas you need
For a height stated in feet and inches:
total inches = (feet × 12) + remaining inches
For a height stated in centimeters:
centimeters = total inches × 2.54
To go the other direction, divide centimeters by 2.54 to get inches. One international foot is 12 inches, so it is 30.48 cm. NIST lists both inch and foot conversion factors. The relationship 12 × 2.54 = 30.48 is exact; a rounded height supplied by a person is still only as precise as that original measurement.
Choose one common unit for the subtraction. If both inputs are in feet and inches, use total inches. If one is in centimeters, centimeters are often easier. Convert only once when possible, and keep a few decimal places until the final answer.
Worked example: 5′7″ versus 6′0″
Write each height as inches:
| Height | Calculation | Total inches | Centimeters |
|---|---|---|---|
| 5 ft 7 in | (5 × 12) + 7 | 67 | 170.18 |
| 6 ft 0 in | (6 × 12) + 0 | 72 | 182.88 |
| Difference | 72 − 67 | 5 | 12.70 |
Notice that 6 ft 0 in means 6 feet and zero additional inches. It does not mean 6.0 inches. Likewise, 5 ft 7 in is not the decimal number 5.7 feet: 0.7 of a foot would be 8.4 inches. Treat the feet and inches as separate fields until you combine them into total inches.
The same subtraction works in centimeters: 182.88 − 170.18 = 12.70 cm. If the inputs came from whole-inch estimates rather than a precise measurement, reporting “about 13 cm” may be more honest than implying that each person’s height is known to the hundredth of a centimeter.
Worked example: 168 cm versus 180 cm
Metric values are straightforward: 180 − 168 = 12 cm. To express that gap in inches, divide by 2.54:
12 ÷ 2.54 ≈ 4.724 inches.
For everyday communication, that is about 4.7 inches, or just under 4¾ inches. If you round to the nearest whole inch, it becomes 5 inches. Those descriptions are not contradictory; they use different rounding. Keep the exact 12 cm as your primary result when the starting values were given in centimeters.
Do not convert 168 cm to “5 ft 6 in” and 180 cm to “5 ft 11 in” before subtracting if you need a precise answer. Rounding each input to a whole inch first can change the gap. Calculate from the original centimeter values, then round the final difference.
Worked example: 5′11″ versus 6′2″
This is where carrying across a foot boundary can feel confusing. Convert to total inches first:
- 5 ft 11 in = (5 × 12) + 11 = 71 inches.
- 6 ft 2 in = (6 × 12) + 2 = 74 inches.
- The difference is 74 − 71 = 3 inches.
- In centimeters, 3 × 2.54 = 7.62 cm.
You can also “borrow” one foot from 6 ft 2 in, making it 5 ft 14 in; then 14 − 11 = 3 in. Total inches are less error-prone, especially when one or both heights are fractional or when a calculator needs to support many inputs.
Mixed units: one person in centimeters, one in feet
Suppose one height is 175 cm and the other is 5 ft 10 in. First convert 5 ft 10 in to inches: 5 × 12 + 10 = 70 inches. Then 70 × 2.54 = 177.8 cm. Subtract 175 cm to get 2.8 cm, or about 1.10 inches.
It is tempting to read 5 ft 10 in as “5.10 feet” and multiply by 30.48. That would be wrong because the “10” is inches, not a decimal fraction of a foot. The 70-inch step prevents this common mistake. You can check mixed-unit inputs with the height converter before putting them on a chart.
What if a height includes half an inch?
Fractional inches fit the same formula. For 5 ft 8½ in, calculate 5 × 12 + 8.5 = 68.5 inches, then multiply by 2.54 to get 173.99 cm. If the second height is 5 ft 10 in, it is 70 inches or 177.8 cm. The gap is 1.5 inches, exactly 3.81 cm using the stated inputs.
Decimal feet are a different notation. A height of 5.5 feet means five and a half feet, which is 5 ft 6 in, not 5 ft 5 in. Multiply the decimal part by 12: 0.5 × 12 = 6 inches. A number such as “5.8” without a unit convention is ambiguous: it could mean 5.8 feet (5 ft 9.6 in) or someone’s shorthand for 5 ft 8 in. Ask which format was intended before calculating a gap.
| If your inputs are… | Good common unit | Why |
|---|---|---|
| Both in feet and inches | Total inches | No decimal-feet confusion |
| Both in centimeters | Centimeters | No conversion required |
| One in cm, one in ft/in | Centimeters or total inches | Convert one input once |
| Rounded or estimated values | Original units, then rounded final gap | Avoid false precision |
How to express the answer clearly
A height difference has a direction and a size. “The difference is 12 cm” gives the size. “Person B is 12 cm taller than Person A” also tells the reader who is taller. If the inputs are estimates, say “about 12 cm taller.” If two inputs are equal, the gap is zero; do not force a taller/shorter label.
You may also see a percentage difference. That number depends on the chosen reference height. For 180 cm versus 168 cm, the 12 cm gap is 12 ÷ 168 × 100 ≈ 7.14% of the shorter person’s height. Relative to the taller person’s height it is 12 ÷ 180 × 100 ≈ 6.67%. Both calculations describe the same 12 cm gap, but answer different questions. State the denominator when publishing a percentage.
An eye-level or shoulder-level claim is less dependable. Body proportions and posture vary, so a 12 cm gap does not put one person’s crown at a fixed facial feature of another. A shared-baseline visual comparison communicates the measured heights without pretending everyone’s proportions are identical.
Rounding without hiding the original measurement
The exact conversion factor does not make an approximate input exact. A person who says “I’m 5 ft 7 in” may be rounding to the nearest inch. Converting that to 170.18 cm is mathematically correct, but the two decimal places reflect the unit conversion, not necessarily the quality of the measurement.
A practical reporting rule is:
- Preserve the original input and its unit.
- Calculate with the exact factor, 2.54 cm per inch.
- Round the displayed result to a level that matches the input—often a whole centimeter or a tenth of an inch for everyday comparisons.
- Use “approximately” when the measurements themselves are approximate.
For example, if two reported athlete heights are 180 cm and 188 cm, the difference in the reports is 8 cm. Writing “3.149606 inches” adds no useful certainty. “About 3.1 inches” is clearer. If two heights were actually measured to the millimeter in a controlled setting, retaining more digits may be justified.
Check the result visually
Arithmetic tells you the gap. A diagram helps you understand it. Put both measured or reported values on the interactive comparison board, switch between centimeters and feet/inches, and keep both figures on the same baseline. If you are comparing named public figures, verify the source of each reported height first. The board displays the numbers you enter; it does not validate biographical claims.
For a quick numerical answer without the full board, use the height difference calculator. For an isolated unit conversion, use the height converter. Each tool serves a different question: conversion changes the unit, subtraction finds the gap, and a visual chart explains the gap.
Sources and method
All worked conversions on this page use the NIST SI factor of exactly 2.54 cm per inch and 12 inches per foot. The examples are original arithmetic illustrations, not measurements or claims about real people. Values shown with “about” are rounded only after subtraction.