Short answer
Most fake Balenciaga bags are made from polyurethane (PU) or PVC coated fabric. Mid-grade fakes use split-grain leather with a polyurethane topcoat. The best 1:1 replicas use lambskin or calfskin, but the tanning, edge paint, hardware, and stitching rarely match the authentic bag. Real Balenciaga City and Hourglass bags are usually lambskin, calfskin, or distressed Arena leather.
The three material tiers
Budget fakes: PU and PVC
These are the bags you see at markets and on street corners. The outer shell is a synthetic fabric coated with polyurethane or PVC. It feels slick and slightly rubbery. The grain pattern repeats because a machine embossed it. PU can look decent in photos. In person it stays stiff, does not develop a patina, and can peel at the corners after a few months. PVC is heavier and has a sharper plastic smell.
Mid-tier fakes: coated split leather
This is the most common leather fake. The base is split-grain leather, which is the lower layer of the hide after the top grain is removed. It gets a polyurethane coating stamped with a grain pattern. It feels more substantial than PU, but the surface is plastic. The giveaway is the edge. Cut a coated split leather strap and you see a fibrous core under a thin plastic skin. Authentic Balenciaga lambskin has color and texture through the whole thickness.
Top-tier replicas: lambskin and calfskin
High-end replicas use real lambskin or calfskin. Some even copy the distressed Arena finish. The material can feel close to authentic in the hand. The problems show up in the details. Counterfeit lambskin is often thinner and more uniform. The edge paint is thicker and shinier. Hardware is usually a zinc alloy with a bright chrome finish instead of the weightier, slightly muted hardware on a real bag. Stitching can be tight, but the thread is often polyester instead of the cotton-wrapped thread Balenciaga uses.
What I check first
I start with smell. Genuine leather smells like hide, slightly animal and earthy. PU and PVC smell like a new shower curtain. Next I look at the grain. Real leather has irregular pores and natural variation in the surface. Synthetic material repeats the same pattern every few inches. Then I press a thumbnail into the surface. Real leather lifts and wrinkles. Coated split leather stays flat or shows a sharp crease.
Edge paint is the tell I trust most. Authentic Balenciaga glazing is thin, matte to satin, and applied in a clean line. Fake bags often have thick, glossy edge paint that cracks or peels. Hardware weight matters too. Pick up the bag by one handle. Real Balenciaga hardware has heft and the strap feels balanced. A fake often feels light and slightly hollow.
Why the material matters beyond looks
Material affects how the bag ages. PU and PVC crack and peel. Coated split leather can flake where the coating breaks down. Lambskin softens and slouches, which is part of the City bag look. A fake that uses stiff coated leather will never drape the same way. If you care about the shape and feel of the real thing, the material is the first thing to verify, not the logo.
Bottom line
Fake Balenciaga bag material falls into three buckets: synthetic PU or PVC, coated split leather, and real lambskin or calfskin on the best replicas. The label 1:1 tells you nothing about material. Ask what the bag is made of, then check the smell, grain, edge paint, and hardware weight in person.