← Quick Reference Charts
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Electrical
Resistor color code, wire gauge, wire color codes, metric prefixes, dB reference, and unit conversions.
Metric Prefixes
| Prefix | Symbol | Power | Example |
|---|---|---|---|
| Tera | T | 10¹² | 1 THz = 1,000,000 MHz |
| Giga | G | 10⁹ | 1 GHz = 1,000 MHz |
| Mega | M | 10⁶ | 1 MHz = 1,000 kHz |
| Kilo | k | 10³ | 1 kHz = 1,000 Hz |
| Base | — | 10⁰ | 1 Hz, 1 V, 1 A, 1 W |
| Milli | m | 10⁻³ | 1 mA = 0.001 A |
| Micro | μ | 10⁻⁶ | 1 μF = 0.000001 F |
| Nano | n | 10⁻⁹ | 1 nF = 0.001 μF |
| Pico | p | 10⁻¹² | 1 pF = 0.001 nF |
Decibel Quick Reference
| dB | Power Ratio | Voltage Ratio | Meaning |
|---|---|---|---|
| 0 dB | 1:1 | 1:1 | No change |
| +1 dB | 1.26:1 | 1.12:1 | Slight increase |
| +2 dB | 1.58:1 | 1.26:1 | Minor increase |
| +3 dB | 2:1 | 1.41:1 | Double power |
| +6 dB | 4:1 | 2:1 | 4× power, 2× voltage |
| +10 dB | 10:1 | 3.16:1 | 10× power |
| +20 dB | 100:1 | 10:1 | 100× power |
| +30 dB | 1,000:1 | 31.6:1 | 1,000× power |
| −3 dB | 0.5:1 | 0.707:1 | Half power |
| −6 dB | 0.25:1 | 0.5:1 | Quarter power |
| −10 dB | 0.1:1 | 0.316:1 | 10% of power |
| −20 dB | 0.01:1 | 0.1:1 | 1% of power |
Resistor Color Code
Mnemonic: Big Brown Rabbits Often Yield Great Big Values Good Work
| Color | Digit | Multiplier | Tolerance |
|---|---|---|---|
Black | 0 | ×1 | — |
Brown | 1 | ×10 | ±1% |
Red | 2 | ×100 | ±2% |
Orange | 3 | ×1k | — |
Yellow | 4 | ×10k | — |
Green | 5 | ×100k | ±0.5% |
Blue | 6 | ×1M | ±0.25% |
Violet | 7 | ×10M | ±0.1% |
Gray | 8 | ×100M | ±0.05% |
White | 9 | ×1G | — |
Gold | — | ×0.1 | ±5% |
Silver | — | ×0.01 | ±10% |
AWG Wire Gauge Reference
| AWG | Diameter | Resistance | Max Current |
|---|---|---|---|
| 0 | 8.25 mm | 0.161 Ω/km | 150 A |
| 2 | 6.54 mm | 0.256 Ω/km | 95 A |
| 4 | 5.19 mm | 0.407 Ω/km | 70 A |
| 6 | 4.11 mm | 0.648 Ω/km | 55 A |
| 8 | 3.26 mm | 1.03 Ω/km | 40 A |
| 10 | 2.59 mm | 1.64 Ω/km | 30 A |
| 12 | 2.05 mm | 2.60 Ω/km | 20 A |
| 14 | 1.63 mm | 4.14 Ω/km | 15 A |
| 16 | 1.29 mm | 6.59 Ω/km | 13 A |
| 18 | 1.02 mm | 10.5 Ω/km | 10 A |
| 20 | 0.812 mm | 16.7 Ω/km | 7.5 A |
| 22 | 0.644 mm | 26.5 Ω/km | 5 A |
| 24 | 0.511 mm | 42.1 Ω/km | 3.5 A |
Wire Color Codes
| Standard | Wire Color | Meaning |
|---|---|---|
| Automotive (SAE) | Black | Ground / negative return |
| Automotive (SAE) | Red | Battery positive / switched power |
| Automotive (SAE) | Yellow | Battery constant positive (memory) |
| Automotive (SAE) | Green | Right front speaker positive |
| Automotive (SAE) | White | Left front speaker positive |
| Marine (ABYC) | Yellow/Red stripe | Starting circuit / bilge blower |
| Marine (ABYC) | Red | DC positive (ungrounded conductor) |
| Marine (ABYC) | Black or Yellow | DC negative (grounded conductor) |
| Marine (ABYC) | Green or Green/Yellow | DC grounding conductor |
| Marine (ABYC) | Dark Blue | Cabin and instrument lights |
| Marine (ABYC) | Brown | Generator armature / bilge pump |
| Aviation (MIL-W-5088) | White | General wiring (most common) |
| Aviation (MIL-W-5088) | Red | DC power bus |
| Aviation (MIL-W-5088) | Black | Ground / negative |
| Aviation (MIL-W-5088) | Blue | AC power |
| AC Mains (US NEC) | Black | Hot (line) |
| AC Mains (US NEC) | White | Neutral |
| AC Mains (US NEC) | Green or Bare | Safety ground |
| AC Mains (US NEC) | Red | Second hot (240V / 3-phase) |
Imperial to Metric Conversions
| Imperial | Metric |
|---|---|
| 1 inch | 25.4 mm |
| 1 foot | 304.8 mm / 0.3048 m |
| 1 yard | 914.4 mm / 0.9144 m |
| 1 mile | 1.609 km |
| 1 nautical mile | 1.852 km |
| 1 statute mile | 1.609 km |
| 1 oz | 28.35 g |
| 1 lb | 453.6 g / 0.4536 kg |
| 1 psi | 6.895 kPa |
| 1 ft-lb | 1.356 N·m |
| 1 in-lb | 0.113 N·m |
| 1 horsepower | 746 W |
| 1 BTU | 1055 J |
| °F to °C | (°F − 32) × 5/9 |
| °C to °F | (°C × 9/5) + 32 |