Nail the exact color dark blue in your design by using the code from any one of these systems for color identification.
|RGB||r: 0, g: 0, b: 139|
|HSL||h: 240°, s: 100%, l: 27%|
|HSV||h: 240°, s: 100%, v: 55%|
|CMYK||c: 100%, m: 100%, y: 0%, k: 45%|
If you're identifying color for pretty much anything digital, you're working in an RGB colorspace. If the project you're working on requires percentage representation, dark blue is made of 0% red, 0% green, and 55% blue.
If you're identifying color for a print project, you're most likely using a CMYK colorspace—the percentages are 100% cyan, 100% magenta, 0% yellow, 45% black.