Smart Blind Motor Torque Calculator

Estimate the motor torque needed for roller shades, cellular blinds, Roman shades, dual rollers, and exterior screens from shade weight, tube radius, gear efficiency, and safety factor.

01Real blind presets

02Torque inputs

Blind construction

Construction factor covers guide friction, folds, dual fabric layers, and nonvertical load.

Shade width (in)

Measure finished cloth or slat width, not bracket-to-bracket width.

Shade drop (in)

Use full travel from fully open to fully closed.

Fabric weight (oz/yd2)

Use face fabric weight; dual rollers should include both layers.

Tube radius (in)

Torque rises directly with the effective rolling radius.

Bottom rail weight (lb)

Include hem bar, slat, magnets, pull bar, or wind bar.

Gear efficiency (%)

Small gearboxes, tight guides, and worm gears often sit near 55% to 75%.

Safety factor (x)

Use more margin for exterior, tall, dusty, cold, or battery-powered shades.

Select a preset or edit the blind details. The model computes shade mass, lift force, effective tube radius, gear loss, and the motor torque rating to shop above.

15.0 ft2Fabric area1.39 m2 shade surface

1.00xLift factorFree-hanging roller baseline

20 mmEffective radiusIncludes tube radius and fabric build allowance.

78%Gear efficiencyTorque is divided by this drivetrain efficiency.

Core formula: shade mass = area x fabric weight + bottom rail. Lift force = mass x 9.80665. Tube torque = force x effective radius x blind factor. Motor torque N·m = tube torque / gear efficiency x safety factor.

03Motor torque results

Recommended motor torque 0.92 N·m Shop at or above the next standard motor size.

Estimated moving shade weight 1.19 kg 2.63 lb including bottom rail.

Tube load force 11.7 N Static gravity force before friction factor.

Suggested motor class 1.5 N·m Compact roller motor with reserve.

This preset has healthy margin for a small interior roller shade. Confirm the motor also fits the tube diameter and voltage system.

04Blind motor/spec comparison grid

0.8 N·mMicro tube motor

Small light rollers, narrow windows, 25 to 28 mm tubes, low rail weight.

1.5 N·mCompact shade motor

Common bedroom rollers and cellular blinds where calculated need stays below 1.2 N·m.

3 N·mStandard roller motor

Wide interior solar shades, blackout fabric, and moderate cassette friction.

6 N·mHeavy shade motor

Large patio-facing rollers, Roman shades, long drops, and heavier hem bars.

10 N·mLarge tube motor

Exterior screens, oversized fabric panels, wind bars, and higher safety-factor installs.

15 N·m+Specialty drive

Commercial widths, guided side channels, very heavy textiles, or linked shade banks.

05Reference tables

Fabric or shade material	Typical weight	Metric weight	Torque note
Light sheer roller fabric	5 to 8 oz/yd2	170 to 270 g/m2	Usually limited by tube fit more than torque.
Solar screen fabric	8 to 14 oz/yd2	270 to 475 g/m2	Open weave can still need rail weight for straight tracking.
Dimout or blackout fabric	12 to 18 oz/yd2	405 to 610 g/m2	Commonly pushes small windows into 1.5 N·m motors.
Roman shade fabric stack	16 to 28 oz/yd2	540 to 950 g/m2	Fold lift and rings add friction beyond fabric mass.
Exterior screen textile	15 to 26 oz/yd2	510 to 880 g/m2	Use stronger safety factor for side tracks and wind bars.

Tube radius	Metric radius	Torque multiplier	Where it appears
0.50 in radius	12.7 mm	0.67x vs 0.75 in	Small battery shade tubes and light rollers.
0.75 in radius	19.1 mm	1.00x baseline	Many 1.5 in outside-diameter roller tubes.
1.00 in radius	25.4 mm	1.33x vs 0.75 in	Stiffer tubes for wider solar and blackout shades.
1.25 in radius	31.8 mm	1.67x vs 0.75 in	Large tubes, exterior screens, and long spans.
1.50 in radius	38.1 mm	2.00x vs 0.75 in	Heavy commercial tubes where deflection control matters.

Blind construction	Model factor	Efficiency range	Recommended safety factor
Free-hanging roller shade	1.00x	75% to 85%	1.5x to 1.8x for interior use.
Cellular or honeycomb blind	1.08x	65% to 78%	1.7x to 2.0x because cord paths add drag.
Roman shade with folds	1.25x	60% to 72%	1.9x to 2.3x for ring and fold friction.
Dual roller or cassette pair	1.32x	60% to 75%	1.9x to 2.2x when two fabrics share one drive.
Exterior screen with wind bar	1.45x	55% to 70%	2.1x to 2.6x for guides, dirt, and weather.
Guided skylight or incline shade	1.18x	60% to 75%	1.8x to 2.2x for rails and angled travel.

Preset scenario	Shade area	Moving weight	Typical motor class
Kitchen light screen	10.0 ft2 / 0.93 m2	1.1 lb / 0.5 kg	0.8 N·m micro motor.
Bedroom blackout roller	15.0 ft2 / 1.39 m2	2.6 lb / 1.2 kg	1.5 N·m compact motor.
Wide woven solar shade	36.0 ft2 / 3.34 m2	7.0 lb / 3.2 kg	3 N·m standard motor.
Roman living-room shade	20.0 ft2 / 1.86 m2	6.2 lb / 2.8 kg	3 to 6 N·m depending on folds.
Exterior patio screen	56.0 ft2 / 5.20 m2	14.2 lb / 6.4 kg	6 to 10 N·m heavy motor.

06Torque sizing tips

Measure the parts that move. Fabric area gets you close, but the bottom rail, sewn hem, magnets, pull bar, and side-channel drag can outweigh the cloth on smaller shades.

Do not undersize for quiet operation. A motor near its limit may lift slowly, stall when cold, or miss position calibration. Choosing the next standard N·m class usually improves consistency.

When you are considering the purchase of motorized blinds, you must understand how weight, geometry, and friction plays crucial roles in creating the necessary torque to operate the motor. Most individuals will consider the brand of the blinds or the brand of the remote control as a starting point for their search for motors. However, this isnt the best way to select motors for blinds.

You must determine the amount of torque that the shade require and how much extra capacity the motor should have. Shade weight is one of the primary considerations in determining the motor requirement for blinds. Shade weight is not just the weight of the fabric.

How to Choose a Motor for Your Blinds

The weight of the solar screen does not include the weight of the bottom rail, the magnets, and the side channel of the shade. Additionally, the weight of the fabric will build up on the shade tube as the shade rolls up. The calculator allows you to enter these measurement to help you find the total weight of the shade.

The radius of the shade tube is another critical measurement in calculating the torque the motor must create. If you increase the radius of the tube from half an inch to one inch, the load that the motor have to lift changes, and it may require a different motor. If the radius of the shade tube is large, it is possible that a compact motor will not have the strength to operate the shade.

In such instances, a standard or heavy-duty motor will be required. The calculator will ask for the radius of the shade tube as one of the measurements. Another consideration is gear efficiency.

If there is a gearbox within the shade tube, it may only allow three-quarters of the motors power to reach the shade. In some instances, the power that reaches the shade may be even less. To account for this, the motor that the motor calculator calculates will not be underpowered.

You can also introduce a safety factor for the motor to provide it with the extra capacity to overcome additional variable like dust within the shade or cold temperatures. Finally, the construction of the shade will affect the amount of torque the motor must provide. If the shade is a free-hanging roller shade, it will require less torque than a cellular shade because cellular shades has cord friction and resistance within each cell.

Roman shades require more torque than a cellular shade because the motor must lift folds of fabric in sequence. Finally, if the shade is an exterior screen, it will require the most torque to operate because exterior screens have wind bar or side tracks. The calculator accounts for these different shade constructions so that you dont have to memorize the different charts for different shades.

While the reference tables provide general information about the weights and motor classes for shades, the reference tables should not replace the specific calculation that are required for your specific shade. The reference tables can help you to understand how the radius of a shade will impact the torque that is required to move the shade, but the calculator will provide you with the specific torque that is required for your shade. You should not assume that every blackout shade requires the same motor, nor should you assume that every shade that is described as “wide solar” shade will be able to fit onto a small diameter shade tube.

In order to improve the accuracy of the calculations that the calculator performs, you are encouraged to use the actual weight of the moving parts of the shade rather than the weight of the shade as published by the shade manufacturer. The weight of the hem bar, the tracking weight, and the thickness of the shade as it accumulates on the tube should all be accounted for in the calculation. Most importantly, entering the weight of the bottom rail of the shade separately will prevent the shade from being underweighted in the calculation.

The figure that the calculator provides represent the minimum amount of torque that is required to move the shade. Motors that are operating near their limit will tend to slow down, lose calibration, or even fail at an earlier point in their expected lifespan than the motor that is calculated to be required for the shade. Therefore, it is recommended that you increase the size of the motor by one size in relation to the calculations, especially for battery-powered shades.

Battery-powered motors will not provide the same amount of torque when the batteries is low. In addition to the factors that are described in the calculation of the torque requirement for the shade, other factors that may increase the torque that is required for the shade may also occur. For instance, cold weather, dust, and other environmental factors may increase the required torque to move the shade.

You may use the safety factor that is provided in the calculator to account for these environmental factors. For instance, exterior screen shades may require a higher safety factor due to the impact of the wind load and temperature difference between indoors and outdoors. However, interior shades, such as those for bedrooms may require a lower safety factor.

Even at a lower safety factor, the extra torque will prevent the motor from laboring if the shade fabric has stretched over time. The purpose of the calculator is to provide you with information regarding the motor that is required for your shade based off the actual condition of the shade. Once you know the requirement for torque, it becomes easier for you to determine the diameter of the tube for the shade and the power source that will be used for the shade.

The calculator will provide you with a figure that is used to purchase the motor or to provide information to an installer of the shade.