With the free roller shutter motor calculator, you can determine the weight of your shutter curtain, the required torque and the right tubular motor in seconds – for PVC, aluminium and wooden roller shutters with 40, 60 or 70 mm octagonal shafts.
In brief: The torque of a roller shutter motor depends on the weight of the curtain and the winding radius of the shaft. Rule of thumb: torque (Nm) = curtain weight (kg) × 9.81 × winding radius (m) × 1.5. A PVC roller shutter measuring 1.20 × 1.40 m weighs around 7.6 kg and needs about 5.6 Nm on a 60 mm shaft – a 6 or 10 Nm motor is enough.
Result
Guide values based on the formula torque = curtain weight × 9.81 × winding radius × 1.5 (reserve for friction). The motor data sheets are authoritative. If in doubt, we will size the motor for you: phone +49 40 50694631.
How the roller shutter motor calculator works
First, the curtain area (width × height) is multiplied by the weight per square metre. This gives the torque the motor must deliver to lift the curtain over the winding radius. The factor 1.5 is a reserve for friction in the guide rails and for the wound-up curtain, which increases the radius. The calculator then selects the next higher torque rating of the suitable A-OK motor.
| Curtain material | Weight per m² (guide value) |
|---|---|
| PVC | approx. 4.5 kg |
| Aluminium, foam-filled | approx. 5 kg |
| Wood or extruded aluminium | approx. 10 kg |
Which motor fits which shaft?
- 40 mm octagonal shaft: A-OK AM35 tubular motor with 6 or 10 Nm, with switch or radio.
- 60 mm octagonal shaft: AM45 mechanical (15–50 Nm, wall switch), AM45 radio tubular motor (6–30 Nm, obstacle detection) or AM45 battery solar (10/20 Nm, without power cable).
- 70 mm shaft and larger: AM45 with a suitable adapter – contact us.
Frequently asked questions about roller shutter motors
How heavy is a roller shutter per square metre?
A PVC roller shutter weighs around 4.5 kg per m², foam-filled aluminium about 5 kg per m², wood or extruded aluminium around 10 kg per m². A 2 m² PVC roller shutter therefore weighs about 9 kg.
What torque do I need for a 2 m² roller shutter?
Made of PVC (approx. 9 kg) on a 60 mm shaft: 9 × 9.81 × 0.05 × 1.5 ≈ 6.6 Nm. The next higher rating is chosen, i.e. 10 Nm. Made of wood (approx. 20 kg), it is around 14.7 Nm, i.e. 15 Nm.
Does a 45 mm motor fit into a 40 mm shaft?
No. Only a 35 mm motor such as the A-OK AM35 fits into a 40 mm octagonal shaft. For 60 mm shafts and larger, the 45 mm motor is the standard solution.
What happens if the motor is too weak?
A motor that is too weak pulls the curtain up slowly or not at all and overheats more quickly. So always choose the next higher torque rating – a slightly stronger motor does no harm.
Can I motorise a roller shutter without a power cable?
Yes, with the A-OK AM45 battery-solar tubular motor. It has a built-in lithium battery and is charged via a small solar panel – no power cable to the shutter box is needed.
Advice and ordering
All motors are in stock in Hamburg and ship within 24 hours. Which type fits is shown in the roller shutter motor comparison. More on selection, installation and prices in the guide Retrofitting and replacing roller shutter motors and at Sun protection motors. Questions? Phone 040 50694631 (Mon–Fri 8 am–5 pm) or Contact form.
In the glossary: Octagonal shaft · Tubular motor
Technically reviewed by Dietmar Heiken, Sales, Vent Systems HDI GmbH, Hamburg – around 20 years of industry experience. Questions? Phone +49 40 50694631 or info@ventsystems.de
Last updated: 27.10.2026
Questions? 040 50694631 · info@ventsystems.de
