How to sell products by weight and adjust pricing accordingly?

Hello, I have a similar problem and I’d like your recommendation

Setting up a store to sell Fresh Meat per pound at $X per pound.

The problem is that these cuts weight sometimes 4Lbs, sometimes 3.25 Lbs .

Let’s say I get a 4 Lbs Flank steak order, my flank pieces will not be exactly 4 lbs. How do I manage this .

How do you charge an approx weight of 4 Lbs and the adjust for the actual weight of the cut.

Please advice.