The number in a Sonesse name is the motor's diameter class, not its power. A Sonesse 50 is not five times stronger than a Sonesse 30. It is a physically bigger motor that needs a bigger tube, and inside each size Somfy sells several torque ratings. Confusing the two is how installers end up with a motor that will not fit the tube they already ordered.
Read the size and the model code separately
Two numbers do two jobs. The family size (28, 30, 40, 50) tells you the smallest tube the motor will slide into. The model code stamped on the label tells you the torque: in 506S2 the 06 means 6 Nm, in 510S2 the 10 means 10 Nm, in 404S2 the 04 means 4 Nm.
So a Sonesse 50 510S2 and a Sonesse 50 506S2 take the same tube and the same crown, and differ only in pulling power. A Sonesse 40 404S2 and a Sonesse 50 504A8 share a torque rating of 4 Nm but will not swap, because one needs a 1.46 in bore and the other needs a 50mm one. Our guide to Somfy model codes breaks the pattern down further.
The four sizes, on Somfy's own figures
Every row below comes from Somfy's published product record for that exact part number, not from a range brochure.
| Motor | Part | Torque | Speed | Noise |
|---|---|---|---|---|
| Sonesse 28 WireFree Zigbee | 1241755 | 1.1 Nm | 20 rpm | 44 dB |
| Sonesse 28 WireFree RTS | 1003297 | 1.1 Nm | 20 rpm | 49 dB |
| Sonesse 30 RTS 24V DC | 1241142 | 2 Nm | 25 rpm | 47 dB |
| Sonesse 40 RTS 404S2 | 1240380 | 4 Nm | 36 rpm | 42 dB |
| Sonesse 50 506S2 RTS | 1001809 | 6 Nm | 32 rpm | 45.1 dB |
| Sonesse 50 510S2 RTS | 1001807 | 10 Nm | 32 rpm | 47.2 dB |
| Sonesse ULTRA 50 504A8 DC RTS | 1134023 | 4 Nm | 25 rpm | 35 dB |
| Sonesse ULTRA 50 506A2 RTS | 1002562 | 6 Nm | 24 rpm | 38 dB |
Sources: Somfy's product records for 1241755, 1241142, 1240380, 1001809, 1001807, 1134023 and 1002562.
Which size fits your shade
Sonesse 28. A 1.1 Nm battery motor for small, light shades on narrow tubes. It suits café blinds, cellular shades and retrofits into windows with no power nearby. Ask it to lift a wide blackout roller and it will stall.
Sonesse 30. Somfy publishes a 1.13 in minimum internal diameter, which makes it the smallest practical choice for a discreet interior shade. At 2 Nm it handles light to medium roller shades up to roughly 40 in wide in standard solar fabric.
Sonesse 40. The 1.46 in bore opens up the 40mm tube range, and the family spans 4 Nm through 9 Nm. This is the size most mid-width residential shades land on.
Sonesse 50. The 50mm range runs from 6 Nm to 35 Nm and takes the 2 in and 2.5 in tubes that dominate larger residential and commercial work. Wide blackout, dual-roller and tall shades belong here.
When a shade sits on a boundary between two sizes, go up. The price gap between a 6 Nm and a 10 Nm motor is small next to pulling a stalled motor back out of a finished tube. The full sizing guide works through fabric weight and roll radius.
Where ULTRA earns its price
ULTRA is the quiet build of the same Sonesse 50 chassis, and the gap is bigger than the marketing suggests. A standard 506S2 is rated 45.1 dB. Its ULTRA equivalent, the 506A2, is rated 38 dB. The 504A8 drops to 35 dB.
Decibels are logarithmic, so 45 dB to 35 dB is not a ten percent improvement. It is roughly the difference between a shade you hear cross the room and one you notice only because the light changed. In a bedroom, a boardroom or a hotel suite on a morning schedule, that is the whole specification.
ULTRA does cost speed. The 506A2 runs 24 rpm against the standard 506S2's 32 rpm, so a tall shade takes noticeably longer to travel. On a bank of shades, quiet usually wins anyway.
Speed is a trade, not a free upgrade
Within a family, torque and speed pull against each other. The Sonesse 40 404S2 runs 36 rpm at 4 Nm. Step up to 9 Nm in the same family and speed drops to 14 rpm. Nothing is wrong with either; they are built for different jobs.
Matching speeds across a bank matters more than raw speed. Shades that start together and finish seconds apart look broken, even when every motor is correctly sized.
Three things to confirm before you order
The tube's inside diameter, not its outside. A thick wall or an internal profile eats usable bore. A crown that fits a 2 in round tube will not fit a 2 in profiled tube.
The head type. Star and square heads take different brackets. The Sonesse ULTRA 50 DC motors use a square head, so a star bracket will not hold one. Check the head on the listing before you buy the bracket.
The control protocol. RTS, Zigbee, SDN and wired are fixed at manufacture and cannot be changed later. Match whatever the property already speaks, or read our control systems comparison first.
Common questions
Can I put a Sonesse 50 motor in a 40mm tube?
No. The 50 series needs a 50mm bore. If the tube is already cut and installed, your options are a Sonesse 40 with enough torque for the load, or a new tube.
Is a Sonesse 40 409R2 stronger than a Sonesse 50 506S2?
Yes, on torque. The 409R2 delivers 9 Nm against the 506S2's 6 Nm. They are not interchangeable, because they need different tubes and different crown and drive sets.
Does ULTRA change the tube or bracket I need?
The tube is the same 50mm. The bracket can differ, because the ULTRA 50 DC motors carry a square head rather than a star head. Confirm the head type on the product page.
Which Sonesse is quietest?
Of the parts in the table above, the Sonesse ULTRA 50 504A8 at 35 dB. The Sonesse 28 WireFree RTS at 49 dB is the loudest, which is the trade you make for a battery motor with no wiring.
Every figure above is taken from Somfy's published record for the specific part number, linked in the sources line. Browse the full range in Somfy Sonesse Motors, or the battery range in WireFree and Battery Motors.
