Acier → Benjamin Moore
The closest Benjamin Moore matches for Sherwin Williams Acier (SW 9170-2), ranked by perceptual color distance.
Finding a Benjamin Moore Equivalent for Acier
If you love Sherwin Williams Acier but need a Benjamin Moore alternative, you are not alone. This is one of the most common cross-brand paint matching searches, whether you are working with a painter who prefers Benjamin Moore, your local store does not carry Sherwin Williams, or you simply want to compare prices across brands before committing.
Acier (SW 9170-2) is a medium-dark gray with cool steel gray undertones. A cool, steely gray. Named for the French word for steel. Neutral and industrial. Between Magnetic Gray and Dovetail. To find a good Benjamin Moore match, we need a color that captures not just the right depth (LRV 25) but also that specific undertone character. That is where Delta E color science comes in.
We calculated the perceptual color distance between Acier and every Benjamin Moore color using the CIE2000 Delta E formula, which measures how different two colors look to the human eye. A Delta E under 2 means most people cannot tell the colors apart. Between 2 and 4, you might notice a difference in certain lighting. Above 5, the difference is clearly visible side by side.
The results are decent but not perfect. The closest Benjamin Moore option is Smoked Oyster (2109-40) with a Delta E of 4, which is a "good match" level match. Smoked Oyster is close. You will want to test a sample before committing, as the difference may be noticeable in certain lighting.
Benjamin Moore Matches for Acier
Smoked Oyster is close.
| Acier | Smoked Oyster | |
|---|---|---|
| LRV | 25 | 34.66 |
| Hex | #9D9D9A | #AFACA6 |
| Undertone | Cool Steel Gray | Cool Neutral Gray |
| Family | Gray | Gray |
Undertone Comparison
Acier has cool steel gray undertones. A cool, steely gray. Named for the French word for steel. Neutral and industrial. Between Magnetic Gray and Dovetail.
Smoked Oyster has cool neutral gray undertones. A cool, balanced mid-tone gray. Named for the delicacy. Neutral and reliable without strong undertone pulls.
These two colors share the same undertone family, which is a good sign for a cross-brand swap. The undertone similarity means they will behave similarly as lighting changes throughout the day, and they should coordinate well with the same accent colors, trim, and furnishings.
How These Colors Behave in Different Lighting
Acier in Your Room
Cool and clean. A neutral gray that reads as steel in all conditions.
Smoked Oyster in Your Room
Neutral and clean. Does not pull warm or cool strongly. Simply a solid mid-tone gray.
LRV and Brightness
Acier has an LRV of 25, while Smoked Oyster has an LRV of 34.66. That means Smoked Oyster reflects more light. If you switch from Acier to Smoked Oyster, the room should feel slightly brighter and more open.
Best Rooms for Acier
Sherwin Williams recommends Acier for: office, bathroom, hallway, accent wall, exterior. With an LRV of 25, this is a medium-dark color that is in the medium range, adding real depth and presence to a room. It works best in rooms with good natural light or as an accent wall color. In smaller or darker rooms, pair it with bright white trim to keep the space from feeling closed in.
Smoked Oyster is recommended for: bathroom, bedroom, office, hallway, living room. The recommended applications differ slightly between brands, but the color's properties should work in the same rooms regardless of which brand you choose. Trust the LRV and undertone data more than the specific room suggestions, and always test in your actual space.
Acier in Other Brands
Looking for Acier equivalents in other brands besides Benjamin Moore? We have matches across all major paint brands.
Frequently Asked Questions
The closest Benjamin Moore match for Acier (SW 9170-2) is Smoked Oyster (2109-40) with a Delta E of 4, which rates as a "good match" match. Smoked Oyster is close. Delta E measures perceptual color distance on a scale where under 2 means nearly identical, 2 to 4 means close with subtle differences, and over 5 means clearly noticeable.
No, they are not identical. Acier is a Sherwin Williams color with cool steel gray undertones and an LRV of 25. Smoked Oyster is a Benjamin Moore color with cool neutral gray undertones and an LRV of 34.66. With a Delta E of 4, the difference is subtle and mainly visible in direct side-by-side comparison. Paint formulations differ between brands, so even colors with similar values can look slightly different due to pigment concentration, binders, and finish.
With a Delta E of 4, the difference is enough that they should not be used on adjacent walls in the same room. You can use them in separate rooms of the same house, but be aware that walking from one room to the other may reveal the difference, especially if the rooms have similar lighting. For the most consistent look, pick one brand for all connected living spaces and reserve the other brand for visually separate rooms like bathrooms or bedrooms behind closed doors.
There are several practical reasons to look for a Benjamin Moore equivalent. Price differences between brands can be significant on large projects. Availability matters if your nearest paint store or home center specializes in Benjamin Moore. Some painters have strong preferences for one brand's formula based on coverage, dry time, or workability. And if you are touching up existing Benjamin Moore work, matching within the same brand gives you the best consistency for seamless results.
Match calculations use Delta E (CIE2000) computed from Lab color space conversion. Color data sourced from manufacturer specifications. Last reviewed: March 22, 2026.