Roll calculator
Enter the GSM, the roll width and length, and the area you need to cover. The figures update as you type. The formula behind them is set out below, with worked examples for 5.0 m and 5.2 m wide rolls.
The formula
- Area in m² = width in metres × length in metres
- Weight in kg = GSM × area in m² ÷ 1,000
- Example: 200 GSM × 5.2 m × 100 m ÷ 1,000 = 104 kg
GSM is grams per square metre, so the nominal weight of a roll is its area multiplied by its GSM.
Worked examples: 100 m rolls
- 100 GSM: 50 kg at 5.0 m wide, 52 kg at 5.2 m wide
- 150 GSM: 75 kg at 5.0 m wide, 78 kg at 5.2 m wide
- 200 GSM: 100 kg at 5.0 m wide, 104 kg at 5.2 m wide
- 300 GSM: 150 kg at 5.0 m wide, 156 kg at 5.2 m wide
- 400 GSM: 200 kg at 5.0 m wide, 208 kg at 5.2 m wide
- 600 GSM: 300 kg at 5.0 m wide, 312 kg at 5.2 m wide
These are nominal fabric weights for a roll 100 m long. Our rolls are 5.0–5.2 m wide and can be cut narrower. Our standard roll is 50 m long (other lengths on request); the next section works it out for 50 m.
Our standard 50 m roll
- 100 GSM: 25 kg at 5.0 m wide, 26 kg at 5.2 m wide
- 200 GSM: 50 kg at 5.0 m wide, 52 kg at 5.2 m wide
- 300 GSM: 75 kg at 5.0 m wide, 78 kg at 5.2 m wide
- 400 GSM: 100 kg at 5.0 m wide, 104 kg at 5.2 m wide
- 600 GSM: 150 kg at 5.0 m wide, 156 kg at 5.2 m wide
A 50 m roll covers 250 m² at 5.0 m wide and 260 m² at 5.2 m wide, before overlaps. Its nominal fabric weight is half the 100 m figure above:
How much does one tonne cover?
- 100 GSM: 10,000 m² per tonne
- 150 GSM: about 6,667 m² per tonne
- 200 GSM: 5,000 m² per tonne
- 300 GSM: about 3,333 m² per tonne
- 400 GSM: 2,500 m² per tonne
Turn the formula round: area in m² = 1,000,000 ÷ GSM for each tonne of fabric. A heavier fabric covers less ground per tonne, so compare price per square metre, not price per kilogram.
Finding the length you need
If you know the area to cover, divide it by the roll width to get the length. A 2,600 m² area with 5.2 m rolls needs 500 m of fabric before overlaps, so allow for overlap and waste in the design, which your engineer sets.
What the calculation does not include
- The core and the packaging, which add to the shipping weight
- The manufacturing tolerance on GSM, so a roll can run slightly above or below nominal
- Overlaps, anchor trenches and cutting waste on site
Treat the figure as a nominal fabric weight. Packed and shipped weights are confirmed with your order.
Wide rolls and container loading
Rolls 5.0–5.2 m wide are longer than the width of a shipping container, so they are loaded lying lengthwise. A 20 ft container is about 5.9 m long inside, which leaves little spare room beside a 5.2 m roll. Confirm the loading plan and the container weight limit with your freight forwarder before you fix the roll length.
If your site handling or your container plan prefers a narrower roll, rolls can be cut narrower than 5.0 m.
Ordering by weight or by area
Tell us the GSM, the width, the length per roll and the number of rolls, or the area in m². Our export team will confirm the roll count and the shipped weight with your quote. Read how GSM works in our GSM guide, how to choose it for roads in the road geotextile GSM guide, and what to include in an enquiry in the quote checklist. Samples are available on request.
Questions
How do I calculate the weight of a geotextile roll?
Multiply GSM by the width in metres and the length in metres, then divide by 1,000 to get kilograms. A 200 GSM roll 5.2 m wide and 100 m long weighs about 104 kg of fabric.
How much area and weight is in a standard 50 m roll?
A 50 m roll covers 250 m² at 5.0 m wide or 260 m² at 5.2 m wide. At 200 GSM that is about 50–52 kg of fabric. Other roll lengths are available on request.
How many square metres does one tonne of geotextile cover?
Divide 1,000,000 by the GSM. A 200 GSM fabric covers 5,000 m² per tonne, and a 300 GSM fabric covers about 3,333 m².
Is the calculated weight the shipping weight?
No. It is the nominal fabric weight. The core, the packaging and the GSM tolerance change the real figure, so confirm packed weights with your order.
What roll width and GSM can you supply?
Roll widths of 5.0–5.2 m, which can be cut narrower, across a 100–1200 GSM range, with a standard roll length of 50 m (other lengths on request).
