Gray Coverage Calculator
Find the right color type, developer volume, and mix strength for your grey percentage, hair length, and texture.
Your coverage recommendation
Mix strength: 1:1 blend — equal parts natural-level shade and gray-coverage shade
Rule of thumb: 50%+ grey or coarse/resistant strands call for a full-strength permanent tint at 20 volume; lighter grey percentages on fine-to-medium hair usually blend well with a gentler demi-permanent at 10 volume.
Why grey percentage and texture both matter
Grey (non-pigmented) hair behaves differently under color than pigmented hair — it’s often more resistant to penetration, especially when it’s coarse in texture. That resistance is why a higher grey percentage, or a coarse/wiry texture, generally calls for a stronger approach: permanent color at 20 volume rather than a gentler demi-permanent gloss.
Below that threshold, blending a grey-coverage shade with your natural-level shade keeps the result looking like natural hair with a few greys blended in, rather than a flat, uniform color.
Frequently Asked Questions
When do I need permanent color instead of demi-permanent?
Once hair is around 50% grey or more, a permanent tint at 20 volume gives more reliable, longer-lasting coverage than a demi-permanent gloss. Coarse or resistant grey strands are also harder for a gentle formula to penetrate, so this calculator recommends permanent color for coarse/resistant texture even under 50% grey.
Why does the calculator recommend a blend ratio instead of full-strength color?
Below about 30% grey, blending 2 parts of your natural-level shade with 1 part of a grey-coverage shade usually looks more natural than full-strength color, which can look flat or overly opaque on hair that's still mostly its natural color. From roughly 30-49% grey, an equal 1:1 blend balances coverage with a natural finish. At 50%+ grey (or on resistant texture), full-strength color is recommended because there isn't enough natural pigment left to blend against.
What does the developer volume actually do?
10 volume developer processes color with little to no lift — enough to deposit tone and blend a handful of greys. 20 volume is the standard strength for full grey coverage, because it opens the cuticle enough for permanent color to penetrate resistant, non-pigmented grey hair.
How much product should I expect to use?
The estimated amount scales with hair length — around 40 g for short hair, 60 g for medium length, and 90 g for long hair, based on typical full-head, single-process amounts. Very thick or dense hair may need more; always keep extra product on hand.
Is this a substitute for a colorist's judgment?
No. This is an educational starting point based on common salon conventions, not a diagnosis of your specific hair. Hair history (previous chemical treatments, porosity, and prior color) can all change how hair takes color.
Educational estimate — not professional cosmetology or medical advice. Patch-test first and follow your specific product’s instructions; consult a licensed colorist for hair with a complex color history.