Resistor color code calculator
Resistance：
0 Ω
Tolerance：
±0%
Parallel/Series resistor calculator
Series Formula: RTotal = R1 + R2
+ ... + Rn
Parallel Formula: 1/RTotal = 1/R1 +
1/R2 + ... + 1/Rn
Total Resistance：
300 Ω
Ohm's Law
V
A
Ω
V = I × R
- V = Voltage (Volt, V)
- I = Current (Ampere, A)
- R = Resistance (Ohm, Ω)
Calculation Result：
Please Click Calculate
Capacitance conversion calculator
Farad (F):
0.0001 F
Millifarad (mF):
0.1 mF
Microfarad (μF):
100 μF
Nanofarad (nF):
100000 nF
Picofarad (pF):
100000000 pF
Capacitance Unit Conversion
1 F = 1,000 mF
1 mF = 1,000 μF
1 μF = 1,000 nF
1 nF = 1,000 pF
Unit Relationship：
- F - Farad (Farad)
- mF - Millifarad (10⁻³ F)
- μF - Microfarad (10⁻⁶ F)
- nF - Nanofarad (10⁻⁹ F)
- pF - Picofarad (10⁻¹² F)
Voltage divider calculator
V
Ω
Ω
Voltage Divider Formula
Vout = Vin × [R₂ ÷ (R₁ + R₂)]
Among which：
- Vin - Input Voltage
- Vout - Output Voltage
- R₁ - Pull-up Resistor
- R₂ - Pull-down Resistor
Output Voltage：
8 V
Voltage Division Ratio：
0.667
Temperature conversion calculator
Celsius (°C):
25 °C
Fahrenheit (°F):
77 °F
Kelvin (K):
298.15 K
Temperature Conversion Formula
°F = (°C × 9/5) + 32
°C = (°F - 32) × 5/9
K = °C + 273.15
°C = K - 273.15
Temperature Scale：
- °C - Celsius (Water Freezing Point 0°C)
- °F - Fahrenheit (Water Freezing Point 32°F)
- K - Kelvin (Absolute Zero 0K)
Battery runtime calculator
%
Endurance Time：
17 Hour
Theoretical Endurance：
20 Hour
Battery Endurance Formula
Time = Capacity ÷ Current × Efficiency Factor
Theoretical Time = Capacity (mAh) ÷ Current (mA)
Actual Time = Theoretical Time × (Efficiency Factor ÷ 100)
Parameter Description：
- Capacity - Total Charge Capacity of Battery
- Current - Average Operating Current of Device
- Efficiency Factor - Actual Efficiency Considering Losses
Length conversion calculator
Kilometer (km):
0.001 km
Meter (m):
1 m
Decimeter (dm):
10 dm
Centimeter (cm):
100 cm
Millimeter (mm):
1000 mm
Inch (inch):
39.37 inch
Foot (foot):
3.281 foot
Length Unit Conversion
1 km = 1000 m
1 m = 10 dm
1 dm = 10 cm
1 cm = 10 mm
1 inch = 2.54 cm
1 foot = 12 inch
Common Conversions：
- 1 Meter = 3.28084 Foot
- 1 Foot = 0.3048 Meter
- 1 Inch = 2.54 Centimeter
- 1 Centimeter = 0.3937 Inch
555 timer calculator
Ω
Ω
F
Frequency：
481.1 Hz
Duty Cycle：
66.7%
High Level Time：
1.386 ms
Low Level Time：
0.693 ms
555 Timer Formula
Astable Mode：
Frequency = 1.44 / ((R₁ + 2R₂) × C)
High Level Time = 0.693 × (R₁ + R₂) × C
Low Level Time = 0.693 × R₂ × C
Duty Cycle = (R₁ + R₂) / (R₁ + 2R₂)
Notes：
- Resistor value recommended between 1kΩ - 1MΩ
- Capacitor value recommended between 100pF - 1000μF
- Duty cycle always greater than 50%
LED series resistor calculator
V
V
A
Unit
Resistor Value：
495 Ω
Resistor Power：
0.198 W
Recommended Resistor：
510 Ω, 1/4 W
LED Resistor Calculation Formula
R = (Vs - n × Vf) ÷ I
P = I² × R
Parameter Description：
- Vs - Supply Voltage
- Vf - LED Forward Voltage Drop
- I - LED Operating Current
- n - Number of LEDs
- R - Current Limiting Resistor
- P - Resistor Power
dBm to watt converter
dBm：
0 dBm
Watt (W)：
0.001 W
Milliwatt (mW)：
1 mW
Microwatt (μW)：
1000 μW
Common Power Reference
30 dBm
1 W
20 dBm
100 mW
10 dBm
10 mW
0 dBm
1 mW
-10 dBm
100 μW
dBm Conversion Formula
dBm = 10 × log₁₀(P ÷ 0.001)
P = 0.001 × 10^(dBm ÷ 10)
Definition Explanation：
- dBm - Decibel Milliwatt
- 0 dBm = 1 mW (Reference Power)
- Every 3 dBm increase doubles the power
- Every 3 dBm decrease halves the power
Common Applications：
- WiFi Router: 20-30 dBm
- Mobile Signal: 0-20 dBm
- Bluetooth Device: 0-10 dBm
Frequency-to-wavelength calculator
Wavelength：
2997924.58 m
Frequency Wavelength Conversion Formula
λ = c ÷ f
f = c ÷ λ
Parameter Description：
- λ - Wavelength (meter)
- f - Frequency (Hertz)
- c - Speed of Light ≈ 3×10⁸ m/s
Common Frequency Bands：
- AM Broadcast: 530-1700 kHz
- FM Broadcast: 88-108 MHz
- WiFi 2.4G: 2.4-2.5 GHz
- WiFi 5G: 5.15-5.85 GHz
Reactance calculator
Capacitive Reactance Formula：
159.15 Ω
Reactance Calculation Formula
Capacitive Reactance Formula：
Xc = 1 ÷ (2πfC)
Parameter Description：
- Xc - Capacitive Reactance (Ω)
- Xl - Inductive Reactance (Ω)
- f - Frequency (Hz)
- C - Capacitance (F)
- L - Inductance (H)
- π ≈ 3.14159
Filter calculator
Ω
Required Capacitance：
159.15 nF
-3dB Point：
1000 Hz
Filter Calculation Formula
Low-pass Filter：
fc = 1 ÷ (2πRC)
C = 1 ÷ (2πRfc)
Characteristic Explanation：
- Low-pass: Passes low frequencies, attenuates high frequencies
- High-pass: Passes high frequencies, attenuates low frequencies
- -3dB Point: Power attenuated by half
- Attenuation per octave: 6dB
SMD resistor code calculator
Resistor Value：
10 kΩ
Tolerance：
5%
SMD capacitor code calculator
3-digit Code：
First 2 digits: Significant Figures
3rd digit: Power of 10
Example：103 = 10 × 10³ = 10kΩ
4-digit Code：
First 3 digits: Significant Figures
4th digit: Power of 10
Example：1002 = 100 × 10² = 10kΩ
E96 Code：
First 2 digits: E96 Code
3rd digit: Multiplier
Example：01C = 100 × 10² = 10kΩ
SMD capacitor code calculator
Capacitance Value：
100 nF
Voltage Rating：
--
SMD Capacitor Code Rules
2-digit Code：
Directly represents picofarads(pF)
Example：47 = 47 pF
3-digit Code：
First 2 digits: Significant Figures
3rd digit: Power of 10
Example：104 = 10 × 10⁴ = 100,000 pF
Letter Code：
Letter: Capacitance Code
Number: Power of 10
例：A1 = 1.0 × 10¹ = 10 pF
PCB trace width calculator
A
Minimum Trace Width：
39.37 mil
Recommended Trace Width：
50 mil
PCB Trace Width Calculation Formula
Based on IPC-2221 Standard
I = k × ΔT⁰·⁴⁴ × A⁰·⁷²⁵
Parameter Description：
- I - Current (A)
- ΔT - Temperature Rise (°C)
- A - Cross-sectional Area (mil²)
- k - Constant (Inner Layer: 0.024，Outer Layer: 0.048)
Common Specifications：
- 1 oz Copper Thickness = 35 μm = 1.37 mil
- 1 A @ 10°C: ~12 mil (1 oz)
- 1 A @ 20°C: ~40 mil (1 oz)
- 1 A @ 30°C: ~60 mil (1 oz)
Time constant calculator
Ω
Time Constant：
1 ms
Charge 63.2%：
1 ms
Charge 95%：
3 ms
Time Constant Formula
RC Circuit：
τ = R × C
Charging: V(t) = V₀(1 - e^(-t/τ))
Time Constant Meaning：
- 1τ: Charge to 63.2%
- 2τ: Charge to 86.5%
- 3τ: Charge to 95.0%
- 4τ: Charge to 98.2%
- 5τ: Charge to 99.3%
Shunt calculator
A
V
W
Shunt Resistor：
0.01 Ω
Actual Power：
1 W
Recommended Resistor：
0.01 Ω, 1W
Shunt Calculator Formula
R = V ÷ I
P = I² × R
R = P ÷ I²
Parameter Description：
- R - Shunt Resistor (Ω)
- V - Voltage Drop (V)
- I - Full Scale Current (A)
- P - Power Dissipation (W)
Design Points：
- Common Voltage Drop: 50mV, 100mV, 200mV
- Power selection should have margin
- Consider resistor temperature drift effect
- Use four-wire measurement to improve accuracy