GSM stands for grams per square metre. It is the single most useful number on a tarpaulin specification because it tells you how much material is actually in the sheet. Two tarpaulins can look identical on a shop counter and behave completely differently in the field, and GSM is usually the reason.

What GSM really changes

A higher GSM means thicker tape yarn, a denser weave and a heavier lamination. In practice that gives you better tear strength at the eyelets, more resistance to flapping damage in wind, and a longer working life under direct sun. It also means more weight to handle and a higher price per square metre, so heavier is not automatically better.

A practical range guide

  • 90–120 GSM — light, short-term covers. Useful for one-season crop covers, painting sheets and temporary protection where the sheet will be replaced soon.
  • 120–150 GSM — general purpose. The common choice for market stalls, small sheds and covering stock that moves regularly.
  • 150–200 GSM — transport grade. Handles the constant flapping of highway travel and repeated folding much better than lighter sheets.
  • 200–300 GSM — heavy duty. Site covers, machinery protection, long-term outdoor storage and anything left tied down for months.
  • 300 GSM and above — industrial. Fumigation covers, godown partitions, and applications where a failure would be expensive.

Three questions before you order

How long will it stay outdoors? Anything beyond three months of continuous sun exposure should start at 150 GSM with a proper UV stabiliser.

How often will it be moved? Frequent folding wears out the coating at the creases. Transport users are usually better served by a heavier sheet that survives handling.

How is it being tied? Rope tension concentrates at the eyelets. If the sheet is pulled tight over a load, the eyelet reinforcement matters as much as the GSM itself.

Where buyers go wrong

The most common mistake is buying on price per piece rather than cost per season. A 120 GSM sheet that needs replacing twice a year costs more than a 200 GSM sheet that lasts three. The second mistake is ignoring the difference between quoted GSM and delivered GSM — always ask for the actual specification in writing, and buy from a supplier who will state it.

If you are unsure, tell us where the cover will be used, how long it needs to last and how it will be secured. We will recommend a grade rather than simply quoting the cheapest option.