EasyEDA Calculator

Essential calculators for electronics design - resistor color codes, Ohm's Law, voltage dividers, and more.

Resistor Calculator
Ohm's Law
Voltage Divider
Power Calculator
Capacitance

Resistor Color Code: 4-band resistors use the first two bands for digits, third for multiplier, and fourth for tolerance.

Example: Brown (1), Black (0), Red (×100), Gold (±5%) = 10 × 100 = 1000Ω ±5%

Resistor Color Bands

0
1
2
3
4
5
0
1
2
3
4
5
×1
×10
×100
×1K
×10K
×100K
±1%
±2%
±0.5%
±0.25%
±0.1%
±5%

Or Enter Value Directly

Enter resistor value directly

Ohm's Law Formula: V = I × R

Where: V = Voltage (Volts), I = Current (Amperes), R = Resistance (Ohms)

V
Enter voltage in volts
A
Enter current in amperes
Ω
Enter resistance in ohms
W
Enter power in watts

Voltage Divider Formula: Vout = Vin × (R2 / (R1 + R2))

Where: Vin = Input Voltage, Vout = Output Voltage, R1 & R2 = Resistor values

V
V
Vout/Vin
mA

Power Formulas: P = V × I = V² / R = I² × R

Where: P = Power (Watts), V = Voltage (Volts), I = Current (Amperes), R = Resistance (Ohms)

V
A
Ω
W

Capacitor Formulas: Series: 1/Ctotal = 1/C1 + 1/C2 + ... | Parallel: Ctotal = C1 + C2 + ...

Where: C = Capacitance (Farads)

Calculating...

Electronics Design Fundamentals

Electronic design involves calculating component values, analyzing circuits, and ensuring proper operation of electronic devices. These calculators help with common design tasks in PCB design and circuit analysis.

Common Electronic Formulas:

Resistor Color Code Reference

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%

Common Component Values

Electronic components typically follow standard value series:

E6

E6 Series (20% tolerance): 10, 15, 22, 33, 47, 68

E12

E12 Series (10% tolerance): 10, 12, 15, 18, 22, 27, 33, 39, 47, 56, 68, 82

E24

E24 Series (5% tolerance): 10, 11, 12, 13, 15, 16, 18, 20, 22, 24, 27, 30, 33, 36, 39, 43, 47, 51, 56, 62, 68, 75, 82, 91

E48

E48 Series (2% tolerance): 100, 105, 110, 115, 121, 127, 133, 140, 147, 154, 162, 169, 178, 187, 196, 205, 215, 226, 237, 249, 261, 274, 287, 301, 316, 332, 348, 365, 383, 402, 422, 442, 464, 487, 511, 536, 562, 590, 619, 649, 681, 715, 750, 787, 825, 866, 909, 953

Design Considerations

Safety Note: When working with electronic circuits, always ensure proper safety measures. High voltage circuits can be dangerous. Use appropriate personal protective equipment and work with circuits only when power is disconnected unless specifically required for testing.

Frequently Asked Questions

4-band resistors: First two bands are significant digits, third is multiplier, fourth is tolerance.
5-band resistors: First three bands are significant digits, fourth is multiplier, fifth is tolerance.
6-band resistors: First three bands are significant digits, fourth is multiplier, fifth is tolerance, sixth is temperature coefficient.

Calculate the power dissipation using P = I² × R or P = V² / R. Choose a resistor with a power rating at least 50% higher than the calculated dissipation to ensure reliability and account for temperature effects. For example, if your calculation shows 0.3W dissipation, use at least a 0.5W resistor.

Capacitors in parallel: Total capacitance increases (Ctotal = C1 + C2 + ...).
Capacitors in series: Total capacitance decreases (1/Ctotal = 1/C1 + 1/C2 + ...).
This is the opposite of resistors, where series increases resistance and parallel decreases it.

Use a voltage divider for low-current applications like setting reference voltages or biasing transistors. Use a voltage regulator when you need a stable voltage for powering components, especially when the load current varies. Voltage dividers are inefficient and their output changes with load, while regulators provide stable output regardless of load (within their specifications).

Common resistor tolerances: ±20% (rare today), ±10% (general purpose), ±5% (common for most circuits), ±1% (precision circuits), ±0.1% or better (high precision applications). Use higher tolerance (cheaper) resistors where exact value isn't critical (pull-up/down resistors, current limiting for LEDs). Use precision resistors for voltage references, measurement circuits, and filters where accuracy matters.

PCB Design Tips

Common Resistor Values (Ω)

  • 10
  • 22
  • 47
  • 100
  • 220
  • 470
  • 1K
  • 2.2K
  • 4.7K
  • 10K
  • 22K
  • 47K
  • 100K
  • 220K
  • 470K
  • 1M
  • 2.2M
  • 4.7M
  • 10M
  • 22M

Electronic Unit Prefixes

Prefix Symbol Multiplier
Pico p 10⁻¹²
Nano n 10⁻⁹
Micro μ 10⁻⁶
Milli m 10⁻³
Kilo k 10³
Mega M 10⁶
Giga G 10⁹

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