Metric and imperial in one made-to-measure storefront

Made-to-measure retailers with international shoppers meet the same problem: half of their customers measure in centimetres, and half in inches. Building two storefronts is one way to handle it. Building a calculator that accepts both is the other. The Curtain and Blind Calculator ships both measurement systems as first-class inputs on the same Shopify product page.

The shopper picks the unit

A small toggle at the top of the calculator lets the shopper choose centimetres or inches. Width and drop fields update their placeholder text to match. When the shopper switches, existing values convert to the new unit rather than clearing. A merchant who prefers to lock the storefront to one system for a specific market can disable the toggle and expose only the unit that matches the shipping region.

The pricing table stays in the merchant's unit

The merchant does not maintain two pricing tables. They upload one, in whichever unit they price in, and the calculator translates the shopper's input into that unit before the table lookup. A UK merchant with a metric price grid can still take a US order in inches; a US merchant with an imperial grid can still take a UK order in centimetres. The workshop-facing side of the order carries both, so the workshop sees the exact figures they will cut against.

Rounding rules stay honest

Unit conversion introduces small rounding errors that matter at the edge of a pricing band. A 60-inch width converts to 152.4 cm, which sits exactly on a boundary between a 150 to 160 cm band and a 160 to 170 cm band. The calculator applies the merchant's configured rounding rule (nearest, up, or down) consistently, so a shopper switching between units does not see the price flip.

Language and unit are independent

The storefront interface can be shown in English, French, Lithuanian, or Danish. The measurement unit is a separate control. A French merchant serving French shoppers in metric and English tourists in imperial runs the same store, with the shopper choosing both settings independently.

Why it matters for a Shopify store

Shopify stores that serve international customers rarely have the budget to split the storefront in two. Handling metric and imperial in one calculator is what keeps a small curtain shop competitive on cross-border quotes. It is the difference between converting a 10 pm order from a shopper in another country and losing them to a competitor whose calculator does the same job automatically.