List each measurement in the unit your customers use for that product, add the other unit in brackets where buyers compare, and round conversions to figures a person would actually say.

Two systems in one country

Canada went metric decades ago, and Canadians still use both systems, choosing by the thing being measured.

Height is given in feet and inches, the weather in Celsius and the oven in Fahrenheit. Gas is sold by the litre, lumber by the inch and flooring by the square foot.

Nobody finds this confusing in conversation. On a product page it causes trouble when the unit is the wrong one for the product, or when a conversion produces a number nobody recognises.

A shopper who cannot picture the size does not stop to do the arithmetic. They phone to ask, or buy from a site that made it easy.

Each product has a usual unit

For most products, habit has already chosen the unit:

The second is where conversion goes wrong most often, because many of its sizes are names rather than measurements. More on that below.

The customer's unit comes first

The first figure should be the one a customer would use to describe the product to a friend: boots by shaft height in inches, a paint can in litres, a rug in feet.

Put the other unit in brackets after it where some buyers will need it: someone fitting a shelf into a space they measured in centimetres, or comparing with a European product sized the other way.

Not every number needs both. A waist size in inches rarely needs centimetres beside it, and brackets on every figure make a page harder to read.

Round the way a person would

Automatic conversion produces false precision. A six-foot table becomes 182.88 centimetres, which suggests an accuracy the table never had.

Round the converted figure to what a tape measure would show: about 183 centimetres. Keep the original figure exact, since that is the one the product was made to.

Check the arithmetic once, by hand, for each kind of product. Supplier sheets copied from one catalogue to another sometimes carry an inch figure labelled as centimetres, and every page built from them inherits the mistake.

Names that look like measurements

Some numbers on a product page are names, not sizes, and converting them produces nonsense.

A 2x4 is not two inches by four. The board is about one and a half by three and a half inches, or 38 by 89 millimetres, and converting the name describes a board nobody sells.

Television sizes, pipe fittings and jean sizes work the same way. Leave the name alone, and give the actual dimensions on a separate line where they matter.

A worked example

A western wear store in a farming town sells jeans, boots, hats and belts in the store and online, many of them to customers hours away.

Its product pages came from supplier descriptions. Boot makers gave shaft heights in inches, a European hat maker gave head sizes only in centimetres, and the store's own belts had no measurements at all.

The same questions arrived by phone and email every week: whether a 58 is the same as a 7 1/4, how tall a boot is, which belt length goes with a 34 waist.

Hats were the costly part, since every wrong size came back in a box big enough not to crush the brim.

The store settled one approach for each category. Hats now show the North American size first, centimetres in brackets, and a line on measuring a head with a soft tape.

Boots give shaft and heel height in inches. Belts give their length in inches, with the store's own rule for matching a belt to a jean size.

A customer can now answer the sizing question at ten at night, from the page, without waiting for the store to open.

Size charts belong in the text

Many stores show sizing as a picture of the supplier's chart. Phone screens shrink it to a blur, search engines see only an image, and nobody can copy a figure from it.

A short table in text works everywhere. Give each unit its own column, and keep only the columns a customer needs to choose.

Put it on the product page, or one tap away from it. A chart on a separate page loses the product the customer was looking at.

Settings that do the arithmetic

Shop software keeps weights and dimensions in the units chosen in its settings, and uses them to work out shipping.

If the setting says kilograms and someone entered pounds, every rate calculated from those products is off by a factor of about 2.2. Either customers overpay for shipping or the store quietly absorbs the difference.

Check the setting, then weigh a few products and compare. The description can use whichever unit suits the product; the weight and dimension fields must match the setting.

Search in both units

People search the way they measure. Some type "13 inch boots"; others type "58 cm hat".

Where buyers use both systems, having both figures in the text lets the site's own search, and Google, match either. A size filter in inches alone leaves metric shoppers with nothing to choose.

The counter-case

A store selling one kind of product with a settled unit, such as paint or jeans, can use that unit throughout and lose very little.

Stores selling mostly to the United States or Europe face different habits. The principle is the same, the answers differ, and the customer's unit still comes first.

And brackets can be overdone. A page where every number carries its twin is harder to read than one that converts only where buyers compare.

Elsewhere, the advice holds: the customer's unit first, the other in brackets where it helps, rounded the way a person would say it.

Before the next product goes up

  1. List each category and the unit customers use.
  2. Put that unit first on every page.
  3. Add brackets only where buyers compare.
  4. Round converted figures to sensible numbers.
  5. Leave nominal sizes as names.
  6. Check the shipping units against a scale.
  7. Replace chart images with text tables.

Step six is the one that costs money without anyone noticing. A wrong unit in the settings never shows on the page; it shows up in every shipping charge.

Payment, another place where Canadian habits differ, is covered in accepting e-transfers for online orders.

Frequently asked questions

Should product pages use metric or imperial?

Whichever unit customers use for that product. Canadians mix both: clothing and lumber in inches, paint in litres, flooring in square feet, and temperature depending on whether it is weather or an oven.

When should both units be shown?

Where buyers compare across systems, such as fitting a shelf into a space measured in centimetres or choosing a hat sized the other way. Put the second unit in brackets.

How should converted figures be rounded?

To what a tape measure would show. A six-foot table is about 183 centimetres, not 182.88, and the original figure stays exact because the product was made to it.

Why not convert every size automatically?

Some sizes are names, not measurements. A 2x4 is about 38 by 89 millimetres, so converting the name describes a board that nobody sells.

What goes wrong in the shop settings?

Weights entered in one unit while the settings expect another. Every shipping rate calculated from those products is then wrong, by a factor of about 2.2 for pounds and kilograms.

Are size chart images good enough?

No. A picture of a supplier chart blurs on a phone, and to search engines it is only an image. A short text table, with a column for each unit, works everywhere.

West Coast Media Solutions Inc. provides web design, web development, hosting, digital marketing, and business consulting to organisations across Canada, drawing on more than twenty-five years in the field.

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