Somfy motor names look like license plates. 506S2, 525A2, 550R2, 6100R2, 404S2. They are not arbitrary, and once you can read one you can tell a motor's platform, its strength and roughly its speed without opening a spec sheet.
The structure
A code such as 525A2 breaks into four parts:
- 5 is the platform, matched to tube size
- 25 is the torque in newton-metres
- A is the speed class
- 2 is the generation
So a 525A2 is a 500-series motor delivering 25 Nm at the middle speed band, second generation.
The pattern, checked against real part numbers
Every row below is Somfy's own published record for that exact part, not a reading of the code. The code predicts the torque column in all ten cases.
| Code | Part | Torque | Speed | Min tube ID |
|---|---|---|---|---|
| 404S2 | 1240380 | 4 Nm | 36 rpm | 1.46 in |
| 506S2 | 1001809 | 6 Nm | 32 rpm | — |
| 510S2 | 1001807 | 10 Nm | 32 rpm | — |
| 504A8 | 1134023 | 4 Nm | 25 rpm | — |
| 506A2 | 1002562 | 6 Nm | 24 rpm | — |
| 525A2 | 1043423 | 25 Nm | 20 rpm | 1.85 in |
| 550R2 | 1038170 | 50 Nm | 14 rpm | 1.85 in |
| 660R2 | 1162271 | 60 Nm | 14 rpm | 2.37 in |
| 680R2 | 1164261 | 80 Nm | 14 rpm | 2.37 in |
| 6100R2 | 1166289 | 100 Nm | 14 rpm | 2.37 in |
Sources: Somfy's product records for 1240380, 1001809, 1001807, 1134023, 1002562, 1043423, 1038170, 1162271, 1164261 and 1166289.
The first digit: platform and tube size
| 4 | 400 series. LS40 and Sonesse 40 platform. The Sonesse 40 404S2 needs a 1.46 in minimum inside diameter. |
| 5 | 500 series. LT50 and Sonesse 50 platform. LT50 exterior motors need 1.85 in. The busiest platform in residential work. |
| 6 | 600 series. LT60 platform, 2.37 in minimum, for rolling shutters and large exterior assemblies. |
The platform determines which crowns, drives and brackets fit. An LT50 crown will not mount an LT60 motor, and the two platforms share almost no hardware. The LT50 vs LT60 comparison works through exactly what does and does not cross over.
The middle digits: torque in Nm
This is the most directly useful part of the code. Read the digits between the platform number and the letter as the torque rating:
- 506S2 is 6 Nm. 510S2 is 10 Nm. 515S2 is 15 Nm.
- 525A2 is 25 Nm. 530R2 is 30 Nm. 535A2 is 35 Nm.
- 540R2 is 40 Nm. 550R2 is 50 Nm.
- 660R2 is 60 Nm. 680R2 is 80 Nm. 6100R2 is 100 Nm.
- 404S2 is 4 Nm. 409R2 is 9 Nm. 412R2 is 12 Nm.
Note the 6100R2: three digits, because 100 Nm needs them. The pattern still reads cleanly once you know the first digit is the platform.
The letter: speed class
The letter tracks the speed band, and the table above confirms it across ten parts.
| S | Fastest band. 404S2 runs 36 rpm, 506S2 and 510S2 run 32 rpm. Light interior shades. |
| A | Middle band. 506A2 runs 24 rpm, 504A8 runs 25 rpm, 525A2 runs 20 rpm. |
| R | Slow and strong. 550R2, 660R2, 680R2 and 6100R2 all run 14 rpm. Heavy exterior work. |
The relationship is not a coincidence. Within a platform, gearing torque up means gearing speed down, so high-torque motors are slow motors. The one place it breaks is stepping between platforms: 550R2, 660R2, 680R2 and 6100R2 all run 14 rpm, so moving from LT50 to LT60 buys torque at no speed cost.
The trailing digit: generation
The trailing 2 marks the current generation of the platform. Older stock and legacy part numbers may carry different trailing digits. Where a product here replaces a discontinued reference, the listing names both part numbers so you can match what you are replacing.
What the code does not tell you
The control protocol. A 506S2 exists as an RTS version (1001809), an RS485 / SDN version (1002286) and a plain 4-wire wired version (1001814), all with identical torque and speed.
The head type. Star and square heads take different brackets, and the code says nothing about which you have. The Sonesse ULTRA 504A8 (1134023) carries a square head, so a star bracket will not hold it, even though its code looks like its star-headed siblings. Check the head on the listing before ordering the bracket.
The noise rating. ULTRA motors share the numbering but are built quieter: 506S2 is rated 45.1 dB and its ULTRA equivalent 506A2 is rated 38 dB.
For all three, the Somfy part number is what matters. Every listing on this site carries it in the title, so 1001809 gets you the Sonesse 506S2 RTS and nothing else.
Worked examples
- 506S2 is a 500 series motor, 6 Nm, fast band, gen 2. The default interior roller shade motor for 2 in tube. Sonesse 506S2 RTS (1001809)
- 525A2 is a 500 series motor, 25 Nm, mid band, gen 2, on a 1.85 in tube. Cassette awnings and zip screens. Maestria 525A2 RTS (1134083)
- 6100R2 is a 600 series motor, 100 Nm, slow band, gen 2, on a 2.37 in tube. Large rolling shutters. Altus RTS 6100R2 (1166289)
Common questions
Does the number in a Somfy motor code mean the torque?
Yes. The digits between the platform number and the letter are the torque in newton-metres. 506S2 is 6 Nm, 525A2 is 25 Nm, 6100R2 is 100 Nm.
What does the letter in a Somfy model code mean?
It is the speed class. S is the fastest band at 32 to 36 rpm, A is the middle band at 20 to 25 rpm, and R is the slow, high-torque band at 14 rpm.
Is a 510S2 stronger than a 506S2?
Yes, 10 Nm against 6 Nm, and both run 32 rpm. They take the same tube and the same crown, so it is a straight swap for more pulling power.
Does the code tell me whether a motor is RTS?
No. The code describes the mechanism only. The same 506S2 is sold in RTS, RS485 and 4-wire versions. The product title and the listing state the protocol.
With the code read, size the motor properly using How to Size a Somfy Shade Motor, then pick a control protocol. Browse all Somfy motors.
