ColrShift3F51B5 (Indigo 500) — RGB, HSL, CMYK and Contrast
A blue at 48% lightness and 48% saturation, which puts it at 6.87:1 against white and 3.06:1 against black. The tables below give the notation conversions, the tints and shades that keep the hue intact, and the harmonies that pair with it.
Notation conversions
| Notation | Value |
|---|---|
| HEX | 3F51B5 |
| RGB | rgb(63, 81, 181) |
| HSL | hsl(231, 48%, 48%) |
| CMYK | cmyk(65%, 55%, 0%, 29%) |
| Relative luminance | 0.1028 |
| Perceived brightness | 34.1 / 100 |
Contrast against pure white and pure black
Pair this colour with the two extremes to see which is the safer text partner. AA needs 4.5:1 for body text and 3:1 for large text; AAA raises that to 7:1 and 4.5:1.
| Against | Hex | Ratio | AA text | AA large | AAA text |
|---|---|---|---|---|---|
| #FFFFFF | white | 6.87:1 | pass | pass | fail |
| #000000 | black | 3.06:1 | fail | pass | fail |
Tints and shades
Lightness moves in ten-point steps while hue and saturation stay fixed, which keeps the colour recognisable in a scale. The last column is the ratio against white text, useful for deciding where a scale stops working as a background.
| Step | Hex | HSL | vs white text |
|---|---|---|---|
| shade -30 | #171e44 | hsl(231, 48%, 18%) | 16.08:1 |
| shade -20 | #252f69 | hsl(231, 48%, 28%) | 12.43:1 |
| shade -10 | #32408f | hsl(231, 48%, 38%) | 9.27:1 |
| tint +10 | #606fc7 | hsl(231, 48%, 58%) | 4.57:1 |
| tint +20 | #8591d5 | hsl(231, 48%, 68%) | 3.00:1 |
| tint +30 | #abb4e2 | hsl(231, 48%, 78%) | 2.03:1 |
Harmonies
| Scheme | Hex |
|---|---|
| Complementary | #b5a33f |
| Analogous −30 | #3f8cb5 |
| Analogous +30 | #683fb5 |
| Triadic −120 | #51b53f |
| Triadic +120 | #b53f51 |
Measured rather than eyeballed: hue 230.8°, saturation 48.4%, lightness 47.8%, relative luminance 0.1028 — four decimals is the precision the WCAG formula actually needs — and perceived brightness 34.1 out of 100. Entry 38 of 69 in this library, it scores 6.87:1 on white and 3.06:1 on black, a 3.82 spread. The complementary #b5a33f sits 180° away on the wheel, and the scale brackets it with #171e44 below and #abb4e2 above.
Nearby colours
Frequently asked questions
What text colour should sit on 3F51B5?
Black gives 3.06:1 and white gives 6.87:1, so white wins at 6.87:1. That clears the 4.5:1 AA threshold for normal text, but not the 7:1 AAA threshold.
Do the CMYK numbers match a print workflow?
They are the naive conversion from RGB, which assumes no ink limit, no colour profile and no black generation strategy. Real print work needs a profile-aware conversion; the values here are the ones the converter reports and are best used as a starting point for a designer rather than a press-ready separations file.
Convert any other colour, or test a pair against each other, in the ColrShift colour converter and contrast checker. The colour library groups every entry on this site by hue family.