Looking for a Unit-Conversion Widget on Building-Materials Product Pages

We run an online store selling tile, laminate, insulation and other building materials, and right now customers have to do their own math to figure out how many packs or boxes they actually need. Products are sold in different units - some by square meters, some by cubic meters, some by piece or pack - and coverage per package varies from item to item, which leads to under-ordering or over-ordering and extra returns.

We need a widget embedded directly on the product card that lets a shopper enter their area or volume and immediately see the equivalent in square meters, cubic meters, pieces and full packages, rounded up to the nearest whole pack with a visible note about the leftover. The logic should be configurable per product, since coverage and pack size differ across categories, and values need to update instantly without reloading the page.

What we are looking for:
— input field for area or volume with a unit selector
— live recalculation into m2, m3, pieces and packs
— rounding up to full packages with a note on the surplus
— per-product configuration for coverage and units per pack
— clean integration with the product-card layout, mobile-friendly

Please share similar examples and a rough estimate of the time needed.