Slate Blue (BM 1648) vs Steel Blue (BM 823)

Living room with walls painted Benjamin Moore Slate Blue 1648 (simulated) — Slate Blue BM 1648#9BB1BB, LRV 43.2

Living room with walls painted Benjamin Moore Steel Blue 823 (simulated) — Steel Blue BM 823#879EBF, LRV 35.3

Illustrative room. Screen colors vary; test a sample before you paint.

Quick decision

Lighter: Slate Blue, LRV 43.2 vs 35.3.
Warmer: Slate Blue (Lab b* -7.6 vs -19.6). Slate Blue reads blue-gray; Steel Blue reads blue.
North rooms: Slate Blue keeps more brightness (L* 66.8 vs 60.3 in north light); both drift gray about equally.
Trim that works: Harbor Fog BM 2062-70, #D3E7ED, LRV 74.8: the Benjamin Moore white closest in hue to both.
Closeness: deltaE 10.8, clearly different. At 10.8, treat them as different colors.

See each color

Slate BlueBenjamin Moore, BM 1648LRV 43.2, #9BB1BB

Steel BlueBenjamin Moore, BM 823LRV 35.3, #879EBF

Slate Blue (BM 1648) is lighter than Steel Blue (BM 823) and much warmer: LRV 43.2 vs 35.3, deltaE 10.8 (clearly different).

Side by side

Measure	Slate Blue	Steel Blue	Gap
Brand	Benjamin Moore	Benjamin Moore
Color code	1648	823
Hex	#9BB1BB	#879EBF
RGB	155, 177, 187	135, 158, 191
HSL	199°, 19%, 67%	215°, 30%, 64%
LRV (light reflectance value)	43.2	35.3	+7.9
Lab L*	70.9	64.5	+6.4
Lab a*	-5.4	-0.3	−5.1
Lab b*	-7.6	-19.6	+12.0
Undertone	Cool	Cool Blue
Temperature	cool	cool
Color family	Blue	Blue

Same paint, two kinds of light

Slate Blue (BM 1648), published as #9BB1BB

North light (cool, indirect)
#88A7B9

South light (warm, direct)
#AEBBBB

Steel Blue (BM 823), published as #879EBF

North light (cool, indirect)
#7394BD

South light (warm, direct)
#9BA8BF

These swatches and the rooms above are a simulation, not a measurement. How the visualizer works

Which should you pick

Rules of thumb computed from the LRV and Lab values in the table above; no room test was done.

Pick Slate Blue (BM 1648) for a small room or a north-facing room, because it is 7.9 LRV points lighter (43.2 vs 35.3), so it bounces back more of the limited light
Pick Steel Blue (BM 823) for a south-facing room, because its Lab b* is -19.6 against -7.6, so it is the cooler of the two and offsets warm direct sun
Pick Slate Blue (BM 1648) to warm a north-facing room, because it is the warmer of the two (Lab b* -7.6), which counters cool indirect light

Closest matches to Slate Blue in other brands

Closest matches to Steel Blue in other brands

Common questions

Is Slate Blue the same color as Steel Blue?: They are clearly different: a CIEDE2000 difference of 10.8. Slate Blue and Steel Blue are different colors.
Which is lighter, Slate Blue or Steel Blue?: Slate Blue, with an LRV of 43.2 against 35.3.

Full pages

By Paint Pairs. Color data from manufacturer specifications, via PaintDB. The most-viewed colors are checked against each manufacturer's own color page.

Published 2026-10-01. Updated 2026-10-01.

Sources: LRV and hex as published by the manufacturer, via PaintDB (CC BY 4.0). Color differences are CIEDE2000 values computed by this site from the hex values (data snapshot 2026-10-01). Color names and codes belong to their manufacturers.