Centimeters to inches for size charts, fractions included

An inch is exactly 2.54 centimeters, so a size chart converts with one division: centimeters divided by 2.54 gives inches. The work is in the rounding. Ruban Size shows inches as fractions: quarters for body measurements (a 96 cm chest is 37¾ in), eighths under 15 inches (a 26.5 cm foot is 10⅜ in), and heights in feet and inches to the whole inch (1.75 m is 5′ 9″).

How to convert a size chart, step by step

1. Convert each number, not each cell. For "80-84 cm", convert 80 and 84 separately.
2. Divide by 2.54. 80 ÷ 2.54 = 31.50, and 84 ÷ 2.54 = 33.07.
3. Round once, at the end, to the step you've chosen: 31½ to 33 in. Rounding the centimeters first and then converting rounds twice.
4. Use one step for the whole chart: quarters for chest, waist, hips, inseam and lengths; eighths for small values such as hands, wrists and feet.
5. Change the unit in every header. "Chest (cm)" becomes "Chest (in)".
6. Leave the sizes alone. S, M, 75C, 2T and EU 40 are labels, not lengths.
7. Check the steps between sizes. After rounding, the ranges should still follow each other in order, without new gaps or overlaps.

Common values

The first three rows are the room jewelers add to a wrist: ½, ¾ and 1 in (see how to measure your wrist for a bracelet). The 56 cm row is a head, and a US hat size 7 once divided by pi (hat sizes: head circumference to US hat size).

Quarters or eighths

Body measurements round to the quarter inch (¼, ½, ¾). A chest or a waist is measured with a soft tape around a body that breathes, and nobody reads that to the eighth. Under 15 inches (hands, wrists, feet), Ruban Size rounds to the eighth (⅛, ⅜, ⅝, ⅞), because a quarter inch is a large share of a size step there: glove sizes on the Ruban Size template are 2 cm apart, which is only ¾ in.

Prefer decimals? One decimal place works too: 37.8 in rather than 37¾. Pick one style and keep it for the whole chart.

Heights in feet and inches

In the US, heights are written in feet and inches. 175 cm ÷ 2.54 = 68.9 in, rounded to 69 in, which is 5 feet (60 in) and 9 inches: 5′ 9″.

In Ruban Size, the unit of the row decides how a height converts:

• A row in centimeters converts to inches: 175 cm shows as 69 in.
• A row in meters converts to feet and inches: 1.75 m shows as 5′ 9″, and the header "Height (m)" becomes "Height (ft/in)".
• A row in feet and inches converts to centimeters: 5′ 9″ shows as 175.3 cm.

So for a height row that American shoppers will read in feet and inches, type it in meters or in feet and inches.

Kilograms to pounds

A pound is exactly 0.45359237 kg, so divide kilograms by 0.45359237, or multiply by about 2.2046. 12 kg is 26.5 lb; 14 kg is 30.9 lb. Weights show one decimal in both units, and grams convert to ounces.

Common mistakes

• Using 2.5 instead of 2.54. A 100 cm chest becomes 40 in instead of 39¼ in.
• Rounding before converting. Round once, on the inches.
• Forgetting the header. Inches under "Chest (cm)" make every number wrong by a factor of 2.54.
• Converting the size labels. A 75C bra or an EU 40 dress isn't a length.
• Mixing fractions and decimals in one chart.
• Feet typed as decimals. 5.9 ft isn't 5′ 9″: 0.9 ft is 10.8 in, so 5.9 ft is 5′ 10.8″.

What it means for a Shopify store

Shoppers in the US think in inches, and most of the world in centimeters. Two charts, one per unit, mean twice the typing, and the day one of them is updated and the other isn't, they disagree. One chart typed once, with a switch, can't drift.

The switch also has to cover what a shopper reads around the numbers: the units in the headers, heights in feet and inches, weights in pounds. Otherwise the table says inches and the header still says cm.

That's the Kids template, typed in centimeters and kilograms. Switch it to inches: heights, chest and weight convert, and so do the headers.

How Ruban Size converts

• Type in your unit, row by row. Each row has its own unit: mm, cm, m, in, feet and inches, g, kg, oz or lb. The editor reads "35-36", "38 1/8", "38½", "5'9"" and "1,75 m" as numbers, and a value that says its own unit keeps it. The size charts page shows the grid.
• One switch for shoppers. It reads "cm / in", or "Metric / Imperial" when the chart uses other units. Millimeters and centimeters become inches, meters become feet and inches, grams become ounces, kilograms become pounds, and back. Back in its own system, a row shows exactly what you typed.
• Headers follow. "Chest (cm)" becomes "Chest (in)", "Weight (kg)" becomes "Weight (lb)", "Height (m)" becomes "Height (ft/in)". "(M)" is a size and "(G)" a cup, so they stay as they are.
• Rounding. Whole millimeters and grams, two decimals in meters, one in centimeters, kilograms, ounces and pounds; inches with fractions or one decimal, as the store chooses; feet and inches to the whole inch.
• Who sees inches first. Shoppers in the United States, Liberia and Myanmar, by default; everyone else sees the unit the chart is typed in. The choice a shopper makes is remembered on their device for the next product.
• Find my size checks the unit. Type 96 into a chest field in inches and it says "These look like centimeters, and the fields are in inches.", with a button to switch.

Shoes and rings don't convert by division alone: their sizes follow their own scales. For those, use the shoe size converter and the ring size converter. A chart typed in inches, like the women's jeans template, converts the other way with the same switch.

Questions

How do I convert cm to inches?

Divide by 2.54. A 96 cm chest is 37.8 in, which a size chart rounds to 37¾.

What is 175 cm in feet and inches?

175 ÷ 2.54 = 68.9 in, rounded to 69 in: 5 feet 9 inches, written 5′ 9″.

Should a size chart use fractions or decimals for inches?

Either works if the whole chart uses the same one. Fractions are what US tape measures show: quarters for body measurements, eighths for small ones like hands and feet.

How many pounds are in a kilogram?

About 2.2046. A pound is exactly 0.45359237 kg, so 12 kg is 26.5 lb.