We are often asked how to calculate the weight of blind fabric or screen material in order to determine the load requirements for our RollerTrol™ tubular motors. We have created this guide for those wishing to estimate the loading for a particular blind or screen material.

The first step is to find out the weight specification for the material you wish to use. Fabric weight is typically measured in units of 'grams per square meter'.

It is often difficult to obtain this information from suppliers, so if you already have the material you could weigh 1 square meter on a scale. You don't necessarily have to cut it, just holding an appropriate amount of the material on the scale will give you a good approximation, with any remaining material supported by the table surface you are working on.

For our example, we'll consider a very large window blind (10 feet x 18 feet), with a very heavy material: wool felt has a weight of approximately 360 grams per square meter. It is unlikely you would use anything this large with this weight, so you could consider this to be a 'worst case' example.

First, we would calculate the area of the blind:

• Area Conversion Formula: 10 square feet = 0.92 square meters
• Weight Conversion Formula: 1 Kg = 1000 grams = 2.2 lbs
• Fabric Area Calculation: 10' x 18' = 180 sq ft = 16.56 square meters

Total weight would be: 16.56 square meter x 360 grams per square meter = 5,961.60 grams

Final Lift Weight: 5,961.60 grams = 5.96 Kg (rounded) = 13 lbs

Also, keep in mind this situation only exists when the material is fully extended; as it rolls up, the weight decreases. Also, note that the weight of the tube is not important in this calculation, but the weight of the tension bar at the bottom is.

Here is a measured example just for the sake of reference: a typical vinyl roller blind that fits a 27" x 57" window frame weighs about 340 grams, including the plastic tension bar at the bottom.

Another method of calculating the weight is to use a fish scale, holding up just half of the material of an existing 'in place' shade (remove the tension bar and weigh it separately). Multiply the measured weight by 2, add the weight of the tension bar, and you will have a reasonably accurate measure of the required lift capacity.

Once you have your weight calculated, you can use our

tubular motor comparison table

to choose the most suitable motor. The model numbers have direct links to click for detailed specifications and pricing.

We sincerely hope you enjoy using these advanced motors; if you have any questions, please feel free to contact us at any time!