Color Code Calculator

A Color Code Calculator helps in two common contexts:

  1. Digital design — convert and compare colors across HEX, RGB, and HSL models for web/app UI work.
  2. Electronics — decode resistor color bands to get resistance, tolerance, and (optionally) temperature coefficient.

This guide explains how to use such a calculator, the underlying formulas, clear examples, and FAQs.

Color Code Calculator

How to Use the Color Code Calculator

For Web Colors

  1. Enter any one: HEX (e.g., #1E90FF), RGB (e.g., rgb(30,144,255)), or HSL (e.g., hsl(210,100%,56%)).
  2. The calculator instantly returns the other models and previews the color.
  3. Optionally adjust channels (R/G/B, H/S/L) and copy results.

For Resistor Color Codes

  1. Choose band count: 4-band, 5-band, or 6-band.
  2. Select the colors for each band.
  3. The calculator outputs resistance value, tolerance, and (for 6-band) tempco.

Web Color Conversion Formulas

1) RGB → HEX

  • Given R, G, B in [0,255].
  • Convert each to two-digit hex and concatenate:
    HEX = # (R_hex)(G_hex)(B_hex)

Example: RGB(34, 139, 34)
34 → 22, 139 → 8B, 34 → 22 → #228B22 (ForestGreen)

2) HEX → RGB

  • Parse pairs: RR, GG, BB as base-16 integers in [0,255].

Example: #FF7A00 → (255, 122, 0)

3) RGB → HSL

  1. Normalize: r = R/255, g = G/255, b = B/255.
  2. max = max(r,g,b), min = min(r,g,b)
  3. L = (max + min) / 2
  4. If max = min → S = 0, H = 0 (achromatic).
    Else:
    • Δ = max − min
    • S = Δ / (1 − |2L − 1|)
    • H (in degrees):
      • if max=r: H = 60 × ((g − b)/Δ mod 6)
      • if max=g: H = 60 × ((b − r)/Δ + 2)
      • if max=b: H = 60 × ((r − g)/Δ + 4)

4) HSL → RGB

  1. C = (1 − |2L − 1|) × S
  2. X = C × (1 − |(H/60 mod 2) − 1|)
  3. m = L − C/2
  4. Map (C, X, 0) to RGB’ by H sector (0–60, 60–120, …, 300–360).
  5. R = 255 × (R’ + m), G = 255 × (G’ + m), B = 255 × (B’ + m) (round to integers).

Web Color Conversion Examples

Example A: RGB → HEX → HSL

  • Input: RGB(30, 144, 255)
  • HEX: 30→1E, 144→90, 255→FF → #1E90FF (DodgerBlue)
  • HSL:
    • r=0.1176, g=0.5647, b=1.0000
    • max=1.0, min=0.1176, L=(1.0+0.1176)/2=0.5588
    • Δ=0.8824; S=Δ/(1−|2L−1|)=0.8824/(1−|1.1176−1|)=0.8824/0.8824=1.0
    • max=b → H = 60×((r−g)/Δ + 4) = 60×((0.1176−0.5647)/0.8824 + 4)
      = 60×(−0.5079 + 4)= 60×3.4921 ≈ 209.5°
    • HSL ≈ (210°, 100%, 56%)

Example B: HEX → RGB → HSL

  • Input: #FF7A00
  • RGB: (255, 122, 0)
  • HSL (summarized): (28°, 100%, 50%) (a vivid orange)

Resistor Color Code Reference

Digit / Multiplier Colors

  • Black 0 (×10^0)
  • Brown 1 (×10^1)
  • Red 2 (×10^2)
  • Orange 3 (×10^3)
  • Yellow 4 (×10^4)
  • Green 5 (×10^5)
  • Blue 6 (×10^6)
  • Violet 7 (×10^7)
  • Gray 8 (×10^8)
  • White 9 (×10^9)
  • Gold multiplier ×10^−1
  • Silver multiplier ×10^−2

Tolerance Band

  • Brown ±1%
  • Red ±2%
  • Green ±0.5%
  • Blue ±0.25%
  • Violet ±0.1%
  • Gray ±0.05%
  • Gold ±5%
  • Silver ±10%
  • None ±20%

Temperature Coefficient (6th band, ppm/K)

  • Brown 100, Red 50, Orange 15, Yellow 25, Blue 10, Violet 5

Resistor Color Code Formulas

4-Band (D1 D2 Mult Tol)

  • Value (Ω) = (10 × D1 + D2) × Multiplier
  • Tolerance from 4th band.

5-Band (D1 D2 D3 Mult Tol)

  • Value (Ω) = (100 × D1 + 10 × D2 + D3) × Multiplier

6-Band

  • Same as 5-band with an extra tempco band.

Resistor Examples

Example 1: 4-Band

  • Red (2) – Violet (7) – Orange (×10^3) – Gold (±5%)
  • Digits: 27; Multiplier: 10^3 → 27,000 Ω = 27 kΩ ±5%

Example 2: 5-Band

  • Brown (1) – Black (0) – Black (0) – Red (×10^2) – Brown (±1%)
  • Digits: 100; Multiplier: 10^2 → 100 × 100 = 10,000 Ω = 10 kΩ ±1%

Example 3: 6-Band

  • Yellow (4) – Violet (7) – Black (0) – Brown (×10^1) – Red (±2%) – Blue (10 ppm/K)
  • Digits: 470; Multiplier: 10 → 4,700 Ω = 4.7 kΩ ±2%, 10 ppm/K

Practical Tips

  • Designers: Use HSL to tweak lightness/saturation without changing hue; convert to HEX for CSS.
  • Developers: Normalize inputs (e.g., trim #, accept rgb()/hsl() strings) and clamp ranges.
  • Makers: For resistors, read bands left-to-right; the tolerance band (gold/silver) is usually wider and sits on the right.

FAQs (20)

  1. What models does a color calculator support?
    HEX, RGB, and HSL are standard; some tools also support HSV/CMYK.
  2. What’s the range for RGB?
    0–255 per channel.
  3. What are valid HEX formats?
    #RRGGBB and shorthand #RGB.
  4. When should I use HSL?
    When adjusting lightness/saturation while keeping hue constant.
  5. Why do colors look different on screens?
    Different displays, color profiles, and brightness settings.
  6. How do I convert APRX HSL back to RGB accurately?
    Use the HSL → RGB steps with proper rounding to 0–255.
  7. Difference between HSL and HSV?
    Both use Hue; S/L vs S/V treat lightness/value differently. HSL is often friendlier for UI.
  8. What’s a resistor color band order?
    Digits → multiplier → tolerance (→ tempco for 6-band).
  9. How do I spot the tolerance band?
    Gold/silver (or a gap) usually indicates the tolerance band on the right.
  10. What if bands are faded?
    Measure with a multimeter to confirm.
  11. Can gold/silver appear as digits?
    No, they’re only multipliers or tolerance.
  12. What’s the most common tolerance?
    ±1% (brown) and ±5% (gold) parts are common.
  13. How do I compute power rating?
    Not from color bands—check the physical size/spec sheet.
  14. Does wire-wound use same code?
    Many use the same scheme; always verify datasheet.
  15. What’s tempco for precision work?
    Lower ppm/K (e.g., violet 5 ppm/K) means better stability.
  16. How to ensure accessible web colors?
    Check contrast ratios (WCAG) after converting.
  17. Can I lock Hue and vary Lightness?
    Yes—keep H fixed, tweak L; then convert to HEX/RGB.
  18. Why rounding matters?
    Tiny rounding differences can change HEX by a unit.
  19. Are 3-band resistors a thing?
    Older parts exist; modern E24/E96 are typically 4–5 bands.
  20. Can I compute percent difference between two colors?
    Yes—convert to a perceptual space (e.g., LAB) and compute ΔE (advanced).