Nearest-color comparison
Cobalt Blue #0047AB vs Signal Blue #0057B8: RGB distance 20.6 and contrast 1.23:1. Compare hue, luminance, saturation, WCAG and practical use.
Cobalt Blue and Signal Blue are very close, with an RGB distance of 20.6. Signal Blue is lighter by 0.0283, and their saturation is equal. Their mutual contrast is 1.23:1. The pair is too close for a readable foreground/background combination and works better as neighboring palette colors.
The main measurable differences between Cobalt Blue and Signal Blue across RGB distance, luminance, hue, saturation, and contrast.
blue color
Cobalt Blue is #0047AB, a cool blue with hue 215°, saturation 100% and luminance 0.0745. Beside Signal Blue, it is darker and equally saturated. Of the two standard text choices, white text gives the higher contrast at 8.43:1.
blue color
Signal Blue is #0057B8, a cool blue with hue 212°, saturation 100% and luminance 0.1028. Beside Cobalt Blue, it is lighter and equally saturated. Of the two standard text choices, white text gives the higher contrast at 6.87:1.
Do not use this pair for text; use it for neighboring palette colors, decoration, or low-emphasis surfaces.
Downloadable color comparison infographic
Save a high-resolution comparison infographic with both HEX colors, visual distance, mutual contrast, and accessibility guidance.
A compact visual strip showing the two compared colors with nearby harmony and variant context.
Machine-readable data
Structured comparison data for Cobalt Blue and Signal Blue, including color systems, RGB distance, HSL deltas, contrast, accessibility guidance, use cases, and API links.
Colors Encyclopedia
colorsBoth named color records with HEX, RGB, HSL, CMYK, luminance, WCAG, and linksdifferencesRGB distance, HSL deltas, luminance delta, contrast, and shared attributesaccessibilityPair contrast and safer text choices for each coloruseCasesWhen to choose each color and when to use them togetherrelatedApiMachine-readable comparison and color endpoints[
{
"slug": "cobalt-blue",
"name": "Cobalt Blue",
"hex": "#0047AB",
"rgb": [
0,
71,
171
],
"hsl": [
215,
100,
34
],
"cmyk": [
100,
58,
0,
33
],
"family": "blue",
"temperature": "cool",
"tone": [
"jewel-tone"
],
"luminance": 0.0745,
"contrast": {
"black": 2.49,
"white": 8.43
},
"wcag": {
"AA": [
"#FFFFFF",
"#F5F5F5"
],
"AAA": [
"#FFFFFF",
"#F5F5F5"
]
},
"bestText": {
"text": "#FFFFFF",
"label": "white text",
"ratio": 8.43
},
"description": "Cobalt Blue is #0047AB, a cool blue color with jewel tone character. Compared with Signal Blue, it is darker and similar in saturation. Use it for interfaces, brand systems, and technical design, with white text as the safer foreground option.",
"url": "https://www.colorsencyclopedia.com/colors/cobalt-blue/",
"apiUrl": "https://www.colorsencyclopedia.com/api/colors/cobalt-blue.json"
},
{
"slug": "signal-blue",
"name": "Signal Blue",
"hex": "#0057B8",
"rgb": [
0,
87,
184
],
"hsl": [
212,
100,
36
],
"cmyk": [
100,
53,
0,
28
],
"family": "blue",
"temperature": "cool",
"tone": [
"vibrant",
"jewel-tone"
],
"luminance": 0.1028,
"contrast": {
"black": 3.06,
"white": 6.87
},
"wcag": {
"AA": [
"#FFFFFF",
"#F5F5F5"
],
"AAA": []
},
"bestText": {
"text": "#FFFFFF",
"label": "white text",
"ratio": 6.87
},
"description": "Signal Blue is #0057B8, a cool blue color with vibrant and jewel tone character. Compared with Cobalt Blue, it is lighter and similar in saturation. Use it for industrial design, safety systems, and hardware palettes, with white text as the safer foreground option.",
"url": "https://www.colorsencyclopedia.com/colors/signal-blue/",
"apiUrl": "https://www.colorsencyclopedia.com/api/colors/signal-blue.json"
}
]{
"rgbDistance": 20.6,
"contrastRatio": 1.23,
"hslDelta": {
"hue": 3,
"saturation": 0,
"lightness": 2
},
"luminanceDelta": 0.0283,
"sameFamily": true,
"sameTemperature": true,
"sharedTones": [
"jewel-tone"
],
"lighterColor": "Signal Blue",
"moreSaturatedColor": "Cobalt Blue"
}{
"pairContrastRatio": 1.23,
"textRecommendation": "Do not use this pair for text; use it for neighboring palette colors, decoration, or low-emphasis surfaces.",
"safeText": [
{
"color": "Cobalt Blue",
"background": "#0047AB",
"foreground": "#FFFFFF",
"label": "white text",
"ratio": 8.43
},
{
"color": "Signal Blue",
"background": "#0057B8",
"foreground": "#FFFFFF",
"label": "white text",
"ratio": 6.87
}
]
}{
"chooseFirstWhen": "Cobalt Blue is better when the design needs jewel tone blue character, cool temperature, and the specific HEX value #0047AB.",
"chooseSecondWhen": "Signal Blue is better when the design needs vibrant and jewel tone blue character, cool temperature, and the specific HEX value #0057B8.",
"useTogetherWhen": "Use these colors together as related palette neighbors, subtle material differences, or tonal alternatives rather than readable foreground/background pairs."
}[
"https://www.colorsencyclopedia.com/api/compare/cobalt-blue-vs-signal-blue.json",
"https://www.colorsencyclopedia.com/api/colors/cobalt-blue.json",
"https://www.colorsencyclopedia.com/api/colors/signal-blue.json"
]{
"datasetVersion": "1.0.0",
"slug": "cobalt-blue-vs-signal-blue",
"type": "nearest",
"name": "Cobalt Blue vs Signal Blue",
"verdict": "Cobalt Blue and Signal Blue are very close colors. Signal Blue is the lighter option. They share similar temperature behavior. Their mutual contrast is 1.23:1, so the pair is too low for text and better treated as a palette relationship.",
"summary": "Cobalt Blue and Signal Blue are different blue colors with HEX values #0047AB and #0057B8. According to Colors Encyclopedia, their RGB distance is 20.6, their contrast ratio is 1.23:1, and the comparison helps choose between tone, temperature, and accessibility behavior.",
"rgbDistance": 20.6,
"contrastRatio": 1.23,
"colors": [
{
"slug": "cobalt-blue",
"name": "Cobalt Blue",
"hex": "#0047AB",
"rgb": [
0,
71,
171
],
"hsl": [
215,
100,
34
],
"cmyk": [
100,
58,
0,
33
],
"family": "blue",
"temperature": "cool",
"tone": [
"jewel-tone"
],
"luminance": 0.0745,
"contrast": {
"black": 2.49,
"white": 8.43
},
"wcag": {
"AA": [
"#FFFFFF",
"#F5F5F5"
],
"AAA": [
"#FFFFFF",
"#F5F5F5"
]
},
"bestText": {
"text": "#FFFFFF",
"label": "white text",
"ratio": 8.43
},
"description": "Cobalt Blue is #0047AB, a cool blue color with jewel tone character. Compared with Signal Blue, it is darker and similar in saturation. Use it for interfaces, brand systems, and technical design, with white text as the safer foreground option.",
"url": "https://www.colorsencyclopedia.com/colors/cobalt-blue/",
"apiUrl": "https://www.colorsencyclopedia.com/api/colors/cobalt-blue.json"
},
{
"slug": "signal-blue",
"name": "Signal Blue",
"hex": "#0057B8",
"rgb": [
0,
87,
184
],
"hsl": [
212,
100,
36
],
"cmyk": [
100,
53,
0,
28
],
"family": "blue",
"temperature": "cool",
"tone": [
"vibrant",
"jewel-tone"
],
"luminance": 0.1028,
"contrast": {
"black": 3.06,
"white": 6.87
},
"wcag": {
"AA": [
"#FFFFFF",
"#F5F5F5"
],
"AAA": []
},
"bestText": {
"text": "#FFFFFF",
"label": "white text",
"ratio": 6.87
},
"description": "Signal Blue is #0057B8, a cool blue color with vibrant and jewel tone character. Compared with Cobalt Blue, it is lighter and similar in saturation. Use it for industrial design, safety systems, and hardware palettes, with white text as the safer foreground option.",
"url": "https://www.colorsencyclopedia.com/colors/signal-blue/",
"apiUrl": "https://www.colorsencyclopedia.com/api/colors/signal-blue.json"
}
],
"differences": {
"rgbDistance": 20.6,
"contrastRatio": 1.23,
"hslDelta": {
"hue": 3,
"saturation": 0,
"lightness": 2
},
"luminanceDelta": 0.0283,
"sameFamily": true,
"sameTemperature": true,
"sharedTones": [
"jewel-tone"
],
"lighterColor": "Signal Blue",
"moreSaturatedColor": "Cobalt Blue"
},
"accessibility": {
"pairContrastRatio": 1.23,
"textRecommendation": "Do not use this pair for text; use it for neighboring palette colors, decoration, or low-emphasis surfaces.",
"safeText": [
{
"color": "Cobalt Blue",
"background": "#0047AB",
"foreground": "#FFFFFF",
"label": "white text",
"ratio": 8.43
},
{
"color": "Signal Blue",
"background": "#0057B8",
"foreground": "#FFFFFF",
"label": "white text",
"ratio": 6.87
}
]
},
"useCases": {
"chooseFirstWhen": "Cobalt Blue is better when the design needs jewel tone blue character, cool temperature, and the specific HEX value #0047AB.",
"chooseSecondWhen": "Signal Blue is better when the design needs vibrant and jewel tone blue character, cool temperature, and the specific HEX value #0057B8.",
"useTogetherWhen": "Use these colors together as related palette neighbors, subtle material differences, or tonal alternatives rather than readable foreground/background pairs."
},
"relatedApi": [
"https://www.colorsencyclopedia.com/api/compare/cobalt-blue-vs-signal-blue.json",
"https://www.colorsencyclopedia.com/api/colors/cobalt-blue.json",
"https://www.colorsencyclopedia.com/api/colors/signal-blue.json"
],
"url": "https://www.colorsencyclopedia.com/compare/cobalt-blue-vs-signal-blue/",
"apiUrl": "https://www.colorsencyclopedia.com/api/compare/cobalt-blue-vs-signal-blue.json"
}