GSM is the first number on any tarpaulin quote, and the easiest one to misread. This guide explains what it means, how the common grades compare, and how to pick the right one, so you neither overpay for a heavy sheet nor buy one too light for the job.
What GSM means
GSM stands for grams per square metre: the weight of one square metre of the sheet. A higher GSM means more material in every square metre, which generally makes the tarpaulin tougher and better at standing up to long outdoor use. A lower GSM is lighter, easier to handle and costs less.
How the standard grades compare
- 90 GSM: our lightest standard grade, easy to handle and fold.
- 120 GSM: a middle grade for general covering.
- 150 GSM: heavy duty.
- 200 GSM: our heaviest standard grade, for the toughest outdoor use.
For orders of 2 tons we make any GSM from 70 to 200, so the grade can be set exactly for your use.
Which GSM for which job
- Short-term covering, light loads or sheets that are moved often: a lighter grade such as 90 GSM.
- General covering of goods and stored produce for a season: a middle grade such as 120 GSM.
- Truck covers, construction sites and long outdoor exposure: a heavy grade such as 150 GSM.
- Farm pond lining, monsoon sheds and the hardest outdoor jobs: the heaviest grade, 200 GSM.
These are starting points, not rules. Tell us how the tarpaulin will be used and for how long, and we will recommend a grade.
How much does a tarpaulin weigh?
Weight follows directly from GSM: multiply the sheet's area in square metres by the GSM and divide by 1,000 to get kilograms. One square foot is 0.0929 square metres. The table shows the sheet material for some common sizes; the finished tarpaulin weighs a little more because of its reinforced edges.
| Size (feet) | Area (m²) | 90 GSM | 120 GSM | 150 GSM | 200 GSM |
|---|---|---|---|---|---|
| 12 × 18 | 20.07 | 1.8 | 2.4 | 3.0 | 4.0 |
| 18 × 24 | 40.13 | 3.6 | 4.8 | 6.0 | 8.0 |
| 24 × 30 | 66.89 | 6.0 | 8.0 | 10.0 | 13.4 |
| 30 × 40 | 111.48 | 10.0 | 13.4 | 16.7 | 22.3 |
Compare prices only at the same GSM
A 90 GSM sheet uses less than half the material of a 200 GSM sheet of the same size, so their prices are not comparable. When you compare quotes, check that the GSM, size and material match first.
For the full ordering checklist, see how to measure and order tarpaulin in bulk.