Product dimensions and weight for ecommerce: one unit per column, and what each channel accepts

One weight, five spellings

Open a supplier’s spreadsheet at the Weight column and read down it. The first kettle is “2.5kg”. The next is “2500 g”, then “2,5 KG”, then “5.5 lb”, then “approx 2.5” with no unit at all. Five kettles of about the same weight, written five ways.

Product dimensions and weight in ecommerce data need one number per cell and one unit per column, with the unit named in the header and accepted by the channel the data is going to. Google Merchant Center, Shopify and WooCommerce each want that in a different form, and a supplier file rarely arrives in any of them.

Left as it came, the column fails quietly. With units in the cells, a sort by weight is a text sort, and it puts “12 kg” before “2.5kg”. A clean-up that strips commas turns “2,5” into 25. A store set to kilograms that imports “2500” records a kettle of two and a half tonnes.

Spelling variants and “N/A” entries are covered in normalising attribute values. Measurements have rules of their own.

What each channel accepts

Google has two sets of measurement attributes: one describes the product, the other is used to work out delivery costs. Product length, width and height take cm or in, from 1 to 3,000, and product weight takes lb, oz, g or kg, from 0 to 2,000, with decimals supported in every unit.² Delivery weight, the shipping_weight attribute, takes the same four units, from 0 to 2,000 lb or 0 to 1,000 kg.¹ Delivery length, width and height take cm or inch, from 1 to 400 cm or 1 to 150 inches.³

Two of Google’s rules are easy to break with supplier data. Product dimensions must share one unit, or “the information won’t be displayed”.² Delivery dimensions are all or nothing, “Include all dimension attributes if you include any of them”, and Google lists that among the minimum requirements it enforces by disapproving the product.³ Over the weight limit, its instruction is to “use the delivery label [shipping_label] attribute instead to configure delivery rates”.¹

Shopify’s product CSV wants the weight as a bare number of grams, “without the unit of measurement or decimals”: its examples are 5.125 kilograms entered as 5125, and 4 pounds as 1814.⁹ A separate column, Weight unit for display, sets the unit shown on the store.⁹ Packed product length, width and height take cm or in from a fourth column, and the four are filled or left blank together, or the product is not imported.⁹

WooCommerce keeps the unit out of the file altogether. Under WooCommerce > Settings > Products, the store has one weight unit and one dimensions unit, each chosen from a drop-down.¹⁰ The CSV importer’s weight and dimension columns carry the note “Parse only numbers”.¹¹ Nothing in a cell says which unit it is in, so a supplier’s grams imported into a store set to kilograms read as a thousand times the real weight.

Why supplier measurements fail

Supplier measurements fail in five recognisable ways.

• The unit is in the cell, missing or misspelt. “2.5kg” carries its unit, “2500” does not, and “approx 2.5” carries a hedge instead. “KG”, “Kgs” and “kilo” all mean kilogram, and none is its symbol: the SI conventions NPL publishes keep kg in lower case, say that “Unit symbols are unaltered in the plural”, and ask for a space, “25 kg, but not 25-kg or 25kg”.¹²
• The decimal marker is a comma. “2,5 KG” uses the decimal comma, which the SI allows alongside the point.¹² “2,500” is worse: two and a half to one supplier, two and a half thousand to another.
• Two systems in one column. “5.5 lb” among kilograms, or “5 lb 8 oz” in one cell. The arithmetic is exact, because Schedule 1 to the Weights and Measures Act 1985 defines the pound as 0.453 592 37 kilogram and the ounce as 1/16 pound.¹⁴ The hard part is spotting the rows.
• Compound cells in an unknown order. “30 x 20 x 10 cm”, “300x200x100mm”, “H10 W20 D30”: three numbers, a unit at the end if any, and nothing to say which is the height. The millimetres need converting too, since Google’s dimension attributes take only centimetres and inches.²³
• The carton measured instead of the product. A logistics team measures the box, a marketing team the product, and both call the column Dimensions. Google keeps the two apart, with separate attributes for delivery.²

The same rows, before and after

Here are a supplier’s Weight and Dimensions columns for seven kitchen products as they arrived, and the same rows converted to kilograms and centimetres, one measurement per column.

The three metric rows collapse to one set of values, so a filter or a sort treats them as the same. The inch rows convert exactly: 12 inches is 30.48 cm by definition.¹⁴ KT-104 sent two dimensions for three columns, and KT-105 needs a person twice over: “approx” is a hedge rather than a unit, and its dimensions are the box’s.

The blank stays blank. Shopify records 0 for a weight that is not entered, and asks for accurate weights wherever carrier-calculated shipping is used.⁹ A blank you can see is a gap to fill; a zero looks like an answer.

How to convert product units in a spreadsheet

Conversion is nine steps, and each depends on the one before.

1. Keep the supplier’s column. Work on a copy, so every converted value traces back to the cell it came from.
2. Split the number from the unit. One column for the number, one for whatever followed it: the second is your list of what needs converting.
3. Fix the decimal marker. Before any arithmetic, replace a comma between digits with a point, in the measurement columns only. A comma before exactly three digits needs the supplier’s other rows to settle it.
4. Map every unit spelling to one symbol. kg, g, lb and oz for weight; cm, mm and in for length; lower case, never plural.¹²
5. Choose one target unit per column, and name it in the header. “Weight (kg)”, not “Weight”. For a UK catalogue that means kilograms and centimetres, as the section on the UK explains.
6. Convert with exact factors, into a new column. Pounds times 0.45359237 give kilograms, and ounces divided by 16 give pounds. Inches times 2.54 give centimetres, because the Weights and Measures Act 1985 defines the yard as 0.9144 metre and the inch as 1/36 yard.¹⁴ Divide grams by 1,000 and millimetres by 10.
7. Round last, once per destination. Keep the full result and round on the way out. 5.5 lb is 2.494758035 kg, which Shopify’s whole grams make 2495; round to 2.49 kg first and Shopify receives 2490.⁹ For Google’s delivery weight, send whole grams: its attribute page supports decimals, with “1.25 kg” as its example, but its page on weights that are too high says “Decimal values (such as 20.25) are not accepted”.¹⁴
8. Range-check the result. Sort each converted column and read both ends. A 2,500 kg kettle is grams read as kilograms, and Google reports a delivery weight over 1,000 kg or 2,000 lb as too high.⁴ A 300 cm kettle is millimetres read as centimetres, yet well inside Google’s product dimension limit of 3,000: only the sort will catch it.²
9. Write the unit in the form each channel wants. Google gives product weight one range, 0 to 2,000, whatever the unit, so a 2.5 kg kettle goes as “2.5 kg” rather than “2500 g”; its delivery weight goes as “2500 g”.²¹ Shopify gets “2500” in its grams column, and WooCommerce the bare number.⁹¹⁰

Which dimension is which, and whose measurement it is

One supplier writes L × W × H, another H × W × D, and a wardrobe at 200 × 60 × 50 is a different object from one at 50 × 60 × 200. Only the column header can fix the order, so a compound cell becomes three columns, not a tidier compound cell.

Google and schema.org do not even share a name for the first of the three. schema.org’s Product has depth, width, height and weight, and no length property at all.¹⁵ Google’s page notes that “schema.org property Product.depth maps on attribute product_length”.²

A written convention is enough if every row follows it: length is the longer horizontal side, width the shorter, height the vertical as the product stands in use, and a supplier’s depth is your length. For weight, Google asks for the assembled product, and for a bundle “the complete weight of all of the pieces in the listing”.²

Unit pricing, and metric for the UK

Google’s unit pricing measure states how much a product contains, measured “without packaging”, and its base measure the amount the price is shown per.⁵⁸⁶ Certain products advertised in the EU and EFTA countries, the UK, Australia and New Zealand “must be displayed with the unit price based on local regulations and therefore require this attribute”, including products sold by weight, volume, length or area.⁵ The base measure is a whole number plus unit: 1, 10, 100, 2, 4 or 8, or one of four metric combinations, 75cl, 750ml, 50kg and 1000kg.⁶ Without one, Merchant Center reports “Missing product measurement”.⁷

For the UK, Google’s instruction is plain: “Submit metric values if you sell products to the UK”, because imperial units such as fl oz, pt, qt and gal “are interpreted as US imperial units, which are different from the imperial units used in the UK”.⁵ GOV.UK’s guidance points the same way for the goods themselves: “You must use metric measurements (grams, kilograms, millilitres or litres) when selling packaged or loose goods in England, Scotland or Wales.”¹³ An imperial figure may sit alongside but “cannot stand out more than the metric measurement”, and Northern Ireland has different rules.¹³

Metric first, with imperial at most as a second figure, is the safe default for every measurement column in a UK catalogue.

What to do next

Converting every measure to one unit is one of the specification steps in RefynData’s product data enrichment service. Compound cells are split, each weight and dimension is converted to the catalogue’s unit, and the review cross-checks numbers against their category, which is where a 2,500 kg kettle gets flagged. Every value keeps a link to its source, so “approx 2.5” can be checked against the product page rather than trusted. Measurements are one part of what product data enrichment covers.

Start with the headers: decide each measurement column’s unit, write it in, and move every unit out of the cells. Convert the heaviest and largest products first, since Google’s limits and delivery costs bite hardest there. Keep the supplier’s column beside the converted one, and finish before the file is built, because a weight imported in the wrong unit reaches every channel the store feeds. One unit per column is also a line in the product data quality checklist, and the easiest to test.