Why weights vary
Fresh meat is a natural product and butchery involves whole pieces, trimming and cutting. It is not always possible to hit an exact gram target without waste or impractical cuts.
How the estimate works
For meat sold per kilogram, the product page uses the current unit price and the weight you request to calculate an estimated line total. Quantity multiplies that estimate where you order more than one pack.
Final packed weight
Where the product is configured for actual-weight charging, the packed weight is the quantity used for the final charge. The service should show this clearly rather than disguising the difference as a fee.
If a substitution or material weight change would fundamentally alter what you ordered, customer support should resolve it rather than treating the original estimate as unlimited permission to change the order.
Preparation and piece counts
Piece counts shown for cuts are targets unless the product is explicitly sold as an exact count. Natural piece size and the requested total weight can mean the final count varies slightly.