Stihl RMI 422 and 632
Stihl's older wired iMOW generation, replaced before the whole range left UK sale. Only a used buy, and only if a dealer will still service it.
- Lawn sizeup to 3,000 m²
- NavigationPerimeter wire
- Max slope45%
- Versions3
Prices and stock
RMI 422 · up to 800 m² · RRP £1,110
We don’t have a live price from a UK retailer for this version right now.
RMI 422 P · up to 1,500 m² · RRP £1,335
We don’t have a live price from a UK retailer for this version right now.
RMI 632 · up to 3,000 m² · RRP £2,000
We don’t have a live price from a UK retailer for this version right now.
Prices include VAT and are checked automatically. They can change at any time. How we get prices · Links are not affiliate links. Why
Successor: Stihl iMOW (3, 4, 5, 6 and 7)
Prices and stock
iMOW 3 · up to 500 m² · RRP £929
We don’t have a live price from a UK retailer for this version right now.
iMOW 4 · up to 1,000 m² · RRP £1,309
We don’t have a live price from a UK retailer for this version right now.
iMOW 5 · up to 1,500 m² · RRP £1,729
We don’t have a live price from a UK retailer for this version right now.
iMOW 6 · up to 3,000 m² · RRP £2,349
We don’t have a live price from a UK retailer for this version right now.
iMOW 7 · up to 5,000 m² · RRP £3,269
We don’t have a live price from a UK retailer for this version right now.
Prices include VAT and are checked automatically. They can change at any time. How we get prices · Links are not affiliate links. Why
Our verdict
Should you buy the RMI 422 and 632?
A desk-based verdict from the manufacturer’s specifications, manuals and UK warranty terms.
Pros
- Simple wire-guided design that needs no satellite signal or camera
- RMI 632 cuts a 280 mm strip and handles slopes up to 45%
- Stihl dealers have long serviced iMOW mowers
- Should be inexpensive second-hand
Cons
- Two generations old and no longer sold by Stihl UK
- IPX4 weather protection, below the IP56 of later iMOWs
- Base models have no app or mobile connection
- Used batteries may be near the end of their life
- RMI 422 limited to 35% slopes
Who it’s for
- Buyers offered a cheap, well-maintained used unit
- Lawns already wired for an RMI, up to about 2,500 m²
- Owners with a Stihl dealer nearby who will service older iMOWs
Who should avoid it
- You want a new mower with a full warranty
- You don't want a boundary wire
- You want app control or theft tracking: the base models had no mobile connection
Specifications
RMI 422 and 632 specifications
The manufacturer’s published figures, each linked to its source. Where versions differ, each is listed.
| Rated lawn area | RMI 422: 800 m²Source: manufacturer product page RMI 422 P: 1,500 m²Source: manufacturer product page RMI 632: 3,000 m²Source: manufacturer product page |
|---|
| Navigation | RMI 422: Perimeter wireSource: manufacturer manual RMI 422 P: Perimeter wireSource: manufacturer manual RMI 632: Perimeter wireSource: manufacturer manual |
|---|---|
| RTK base station needed | RMI 422: NoSource: manufacturer manual RMI 422 P: NoSource: manufacturer manual RMI 632: NoSource: manufacturer manual |
| 4G | RMI 422: NoneSource: manufacturer manual RMI 422 P: NoneSource: manufacturer manual RMI 632: NoneSource: manufacturer manual |
| Max slope | RMI 422: 35%Source: manufacturer manual RMI 422 P: 40%Source: manufacturer manual RMI 632: 45%Source: manufacturer manual |
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| Cutting width | RMI 422: 200 mmSource: manufacturer manual RMI 422 P: 200 mmSource: manufacturer manual RMI 632: 280 mmSource: manufacturer manual |
|---|---|
| Min cutting height | RMI 422: 20 mmSource: manufacturer manual RMI 422 P: 20 mmSource: manufacturer manual RMI 632: 20 mmSource: manufacturer manual |
| Max cutting height | RMI 422: 60 mmSource: manufacturer manual RMI 422 P: 60 mmSource: manufacturer manual RMI 632: 60 mmSource: manufacturer manual |
| Battery | RMI 422: 42 WhSource: manufacturer manual RMI 422 P: 83 WhSource: manufacturer manual |
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| Weight | RMI 422: 9 kgSource: manufacturer manual RMI 422 P: 10 kgSource: manufacturer manual RMI 632: 14 kgSource: manufacturer manual |
|---|---|
| Dimensions (L × W × H) | RMI 422: 600 × 430 × 270Source: manufacturer manual RMI 422 P: 600 × 430 × 270Source: manufacturer manual RMI 632: 730 × 540 × 270Source: manufacturer manual |
| Noise | RMI 422: 62 dB(A)Source: manufacturer manual RMI 422 P: 62 dB(A)Source: manufacturer manual RMI 632: 62 dB(A)Source: manufacturer manual |
| Noise figure type | RMI 422: GuaranteedSource: manufacturer manual RMI 422 P: GuaranteedSource: manufacturer manual RMI 632: GuaranteedSource: manufacturer manual |
| Water/dust rating | RMI 422: IPX4Source: manufacturer manual RMI 422 P: IPX4Source: manufacturer manual RMI 632: IPX4Source: manufacturer manual |
| RRP | RMI 422: £1,110Source: manufacturer product page RMI 422 P: £1,335Source: manufacturer product page RMI 632: £2,000Source: manufacturer product page |
|---|---|
| Warranty |
links go to the manufacturer source for each figure. Figures are the manufacturer’s own claims unless marked otherwise.
Claims vs reality
Where the brand’s marketing and its own small print don’t agree.
They sayNoise of 62 dB(A).
In practiceThe RMI manuals give a measured sound power of 59 to 60 dB(A) plus a 2 dB(A) uncertainty. 62 dB(A) is the upper bound, not a typical reading. Source
Which version do you need?
The RMI 422 is rated for 800 m² and 35% slopes. The RMI 422 P doubles the battery for 1,500 m² and 40% slopes. The RMI 632 is the larger body, with a 280 mm cut, 45% slopes and a 3,000 m² rating. Connected 'C' and 'PC' versions existed but used 2G, not 4G, and aren't covered here.
How it navigates and sets up
The RMI models follow a perimeter wire around the lawn and use guide wires to find the dock. There's no satellite positioning or camera, so the mower relies on the wire for boundaries and on contact for obstacles. Rated areas are 800–3,000 m² and slope limits 35%–45%, depending on the model. If you're buying one for a lawn that isn't already wired, read our installation guide first, as a new wire kit adds to the cost.
Cutting
Cut width is 200 mm on the RMI 422 models and 280 mm on the RMI 632. Height ranges from 20 mm to 60 mm. The manuals give 62 dB(A) as the upper-bound sound power. Batteries are 42 Wh on the RMI 422 and 83 Wh on the 422 P; Stihl doesn't publish a figure for the RMI 632 in the sources we checked.
App, connectivity and security
The base RMI 422, 422 P and 632 have no mobile module, and Stihl's records for these models don't list an app connection. Settings are made on the mower's own controls. Stihl sold connected C and PC versions, but these used 2G (GSM) rather than 4G, so check with your network that 2G service is still available where you live before relying on one. Weather protection is IPX4.
Running costs, warranty and support
Stihl GB's current iMOW warranty is 5 years with registration and annual servicing, but terms at the time these were sold may have differed, and a used mower is very likely out of cover. Blades and servicing go through Stihl approved dealers. Our winter storage guide explains how to look after an ageing battery.
Should you still buy one?
Only second-hand, cheaply, for a lawn that's already wired, and only after a Stihl dealer confirms it can still service the model. Stihl's last-known UK RRPs, archived from 2024, were £1,110–£2,000; a used unit today should cost a small fraction of that. Ask for the battery's age and the service history.
For a new wired mower, the Husqvarna Automower 310 Mark II and Kress Mission are simple dealer-supported choices, and the Honda Miimo HRM 1000 to 4000 keeps a five-year warranty. If you're starting from scratch, a wire-free model such as the Husqvarna Automower 320 NERA avoids laying wire at all.
Price history
Price history will appear here once we’ve tracked this model for a few days.
Questions owners ask
Frequently asked questions
What replaced the Stihl RMI 422 and 632?
The iMOW 3 to 7 and their EVO versions. Stihl UK redirected the old RMI 632 page to the iMOW 6 EVO. Those newer models have since been withdrawn from UK sale too, so there's no current Stihl robot mower in the UK.
Can I still get parts for a Stihl RMI?
Stihl UK still lists iMOW dealer services, but it doesn't publish which parts remain available for the older RMI models. Ask a Stihl approved dealer about batteries, blades and boards before buying a used one.
Is a used RMI worth buying?
Only at a low price and with a recent battery. Check the charging station, power supply and wire connectors come with it, and budget for a new battery if the seller can't show it has been replaced.
Also consider
Alternatives to the RMI 422 and 632
Similar mowers that trade something for something else: price, wire, slope or size.
Cheaper option
Honda Miimo HRM 1000 to 4000
- Up to 4,000 m²
- Perimeter wire
- 47% slopes
Cheaper option
Husqvarna Automower 310 Mark II
- Up to 1,000 m²
- Perimeter wire
- 40% slopes
Cheaper option
Kress Mission
- Up to 2,500 m²
- Perimeter wire
- 35% slopes
Wire-free alternative
Husqvarna Automower 320 NERA
- Up to 3,300 m²
- Network RTK
- 50% slopes
Owning one
Accessories, guides and tools
Compatible accessories
- AKM 100 small-area module setRRP £26.50
- Care & Clean Kit RM (iMOW & lawn mowers)RRP £22.10
Last updated 2026-09-29. Specs are the manufacturer’s own figures, each linked to its source. How we score · How we get prices · Report an error