Reviewed by Fengqi Tarps · Updated 2026-09-16
A 4 mil description is not enough to reproduce a tarp. Match the finished product by combining dimensions, total weight, weave, coating and fabrication details.
Buying principle: define application, destination, exposure, handling and target life before comparing price.
Mil and GSM measure different things
Mil is a thickness measurement: one mil equals 0.001 inch. GSM is finished weight per square metre. Coating, woven base, color, additives and measurement method mean that one nominal mil value does not convert reliably to one universal GSM.
Use finished weight as a cross-check
Record the actual finished length and width and weigh the complete tarp. Total weight divided by finished area provides a useful finished-weight reference, but hems, ropes, eyelets, patches and packaging must be considered.
Document the complete sample
Confirm weave or yarn construction, lamination, two-side color, waterproof requirement, UV exposure, finished-size tolerance, hem construction, rope reinforcement, corner patches, eyelet material and spacing.
Approve before bulk production
Use an agreed physical sample and written specification. Bulk inspection should check finished size, weight tolerance, eyelet spacing, welds, hems, appearance and packing against that reference.
BUYER FAQ
Direct answers for sourcing teams
Can 4 mil be converted directly to GSM?
No. The measurements describe different characteristics and the relationship changes with the woven base, coating and additives.
Why can two tarps with the same GSM feel different?
Yarn, weave density, lamination, surface finish and reinforcement distribute the same nominal weight differently.
What should I send to match a retail tarp?
Send a physical sample when possible, plus the SKU, finished dimensions, total weight, photos, intended use and required order quantities.