Cook's Blue vs Perfect Periwinkle
Where Cook's Blue belongs to Farrow & Ball's range, Perfect Periwinkle is a Sherwin-Williams color. These are both blues, so the question isn't which hue to choose — it's where within blue to land. They have nearly identical light reflectance values (25 vs 23), so they'll read as similarly Medium in most lighting conditions. Both lean cool, so they'll behave similarly in mixed or changing light conditions. The ΔE 4.6 gap is real but not dramatic — close enough to use together, distinct enough to matter as a choice. Below you'll find 1 real-room photo comparison where both colors appear side by side, plus 5 simulated room previews.
Cook's Blue vs Perfect Periwinkle in Real Spaces
1 real room side by side. Cook's Blue and Perfect Periwinkle are close enough that the difference can be hard to judge from a chip alone — these photos show how each reads at scale, across different spaces and lighting conditions.
House
Seen across an entire facade, subtle tonal differences become pronounced. What reads as nearly the same on a chip often reads as clearly different at scale. The distinction reads clearly at room scale, making the choice between them concrete.
Color Details
Cook's Blue vs Perfect Periwinkle Simulated Comparison
5 simulated room previews — drag the slider on each to see Cook's Blue on one side and Perfect Periwinkle on the other.
Digital color is approximate. These simulations are generated from the manufacturer's hex values and overlaid on grayscale room photos — your screen's calibration, brightness, and viewing angle all affect how they render. Before committing to either color, test physical samples in your own space under the light you actually live with.
More Cook's Blue comparisons
See how Cook's Blue stacks up against other well-photographed colors across different brands and tones.
At LRV 83 vs 25, White Dove is decisively the brighter choice.
Ammonite reflects far more light (LRV 69 vs 25), opening up a space where Cook's Blue encloses it.
At LRV 25 vs 6, Cook's Blue is decisively the brighter choice.
Purbeck Stone reflects far more light (LRV 52 vs 25), opening up a space where Cook's Blue encloses it.
Evergreen Fog reads slightly lighter (LRV 30 vs 25), a gap that shows most in low-lit rooms.
At LRV 52 vs 25, Mizzle is decisively the brighter choice.
Agreeable Gray reflects far more light (LRV 60 vs 25), opening up a space where Cook's Blue encloses it.
At LRV 58 vs 25, Accessible Beige is decisively the brighter choice.
Their light reflectance is nearly identical (LRV 27 vs 25), so neither reads brighter in a room.
French Gray reflects far more light (LRV 43 vs 25), opening up a space where Cook's Blue encloses it.
Cook's Blue reflects far more light (LRV 25 vs 4), opening up a space where Naval encloses it.
At LRV 55 vs 25, Tranquil Dawn is decisively the brighter choice.
A 12-point LRV gap (25 vs 13) makes Cook's Blue the marginally brighter of the two.
At LRV 44 vs 25, Hardwick White is decisively the brighter choice.
Pure White reflects far more light (LRV 84 vs 25), opening up a space where Cook's Blue encloses it.
Cook's Blue reads slightly lighter (LRV 25 vs 21), a gap that shows most in low-lit rooms.
At LRV 66 vs 25, Balboa Mist is decisively the brighter choice.
At LRV 74 vs 25, Shoji White is decisively the brighter choice.
At LRV 83 vs 25, Snowbound is decisively the brighter choice.
At LRV 25 vs 12, Cook's Blue is decisively the brighter choice.
At LRV 68 vs 25, Skimming Stone is decisively the brighter choice.
Dix Blue reflects far more light (LRV 41 vs 25), opening up a space where Cook's Blue encloses it.
Calamine reflects far more light (LRV 68 vs 25), opening up a space where Cook's Blue encloses it.
With LRVs of 25 and 25, the two reflect almost the same amount of light.
At LRV 25 vs 12, Cook's Blue is decisively the brighter choice.
At LRV 45 vs 25, Saybrook Sage is decisively the brighter choice.
Pale Green reads slightly lighter (LRV 31 vs 25), a gap that shows most in low-lit rooms.
Cook's Blue reflects far more light (LRV 25 vs 7), opening up a space where Pine Needle encloses it.
With LRVs of 25 and 24, the two reflect almost the same amount of light.
Guilford Green reflects far more light (LRV 57 vs 25), opening up a space where Cook's Blue encloses it.