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The PCB Calculator is a collection of specialized calculators and reference tools for electronic design and PCB engineering.

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Overview

The PCB Calculator provides tools for:
  • Transmission line impedance calculation
  • Track width sizing for current
  • Via design and thermal calculations
  • Component value selection (resistors, regulators)
  • RF attenuator design
  • Electrical spacing requirements
  • Reference data and color codes

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Calculator Categories

The calculators are organized into logical groups:

General System Design

  • Regulators
  • Resistor Calculator

Power & Isolation

  • Electrical Spacing
  • Via Size
  • Track Width
  • Fusing Current
  • Cable Size

High Speed

  • Wavelength
  • RF Attenuators
  • Transmission Lines

Reference

  • E-Series
  • Color Code
  • Board Classes
  • Galvanic Corrosion

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General System Design

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Regulators Calculator

Design voltage regulator circuits with standard 3-terminal ICs
Features:
  • Select regulator type: LM78xx, LM317, LM337, etc.
  • Calculate resistor values for desired output voltage
  • Power dissipation calculation
  • Component database with common regulators
1

Choose Regulator

Select from dropdown (LM317, LM7805, etc.)
2

Enter Specifications

  • Input voltage
  • Desired output voltage
  • Load current
3

Get Results

  • R1, R2 resistor values
  • Power dissipation
  • Heat sink requirements

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Resistor Calculator

Standard Values:
  • E-series resistor selection (E6, E12, E24, E96, E192)
  • Parallel/series combinations
  • Find closest standard value
  • Calculate tolerances
Substitution:
Find equivalent resistance using series/parallel combinations of standard values

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Power, Current & Isolation

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Electrical Spacing Calculator

Critical for safety in AC/DC applications and high voltage designs
Calculates minimum spacing based on:
  • Voltage: Operating and peak voltages
  • Pollution degree: Environmental conditions
  • Material group: PCB substrate type
  • Standard: IPC-2221, IEC 60664, etc.
Output:
  • Clearance requirements
  • Creepage distance
  • Air gap spacing

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Track Width Calculator

Determine copper trace width for given current carrying capacity
Inputs:
  • Current: Expected current through trace
  • Temperature rise: Allowable heating (typically 10°C)
  • Copper weight: 0.5oz, 1oz, 2oz, etc.
  • Trace length: For resistance calculation
  • Location: Internal or external layer
Outputs:
  • Required trace width
  • Resistance of trace
  • Voltage drop
  • Power loss
Input:
  Current: 3A
  Temp Rise: 10°C
  Copper: 1oz (35µm)
  Location: External

Result:
  Width: 1.5mm (59 mils)
  Resistance: 0.012Ω
  Voltage Drop: 0.036V
  Power Loss: 0.108W
Use wider traces than calculated minimum for better reliability and lower voltage drop

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Via Size Calculator

Via Current Capacity:
  • Calculate maximum current through via
  • Based on via diameter and plating thickness
  • Thermal considerations
Inputs:
  • Finished hole size
  • Plating thickness
  • Temperature rise
Outputs:
  • Maximum current rating
  • Thermal resistance
  • Number of vias needed for design current

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Fusing Current

Determine at what current a PCB trace will melt and act as a fuse
Use Cases:
  • Intentional fuse traces
  • Safety critical designs
  • Verify trace won’t fuse under fault conditions
Calculates:
  • Fusing current for given trace width
  • Time to fuse
  • Energy required

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Cable Size Calculator

Wire gauge selection for cables:
  • AWG (American Wire Gauge)
  • Metric wire sizes
  • Current capacity
  • Voltage drop over distance

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High Speed Design

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Wavelength Calculator

RF and signal propagation:
Calculate wavelength from frequency:
  • Free space wavelength
  • PCB wavelength (with dielectric)
  • Quarter-wave and half-wave lengths
Account for PCB dielectric:
  • FR-4: εr ≈ 4.5
  • Rogers: various εr
  • Custom materials
Formula: 
λ = c / (f × √εr)

where:
  λ = wavelength
  c = speed of light
  f = frequency  
  εr = relative permittivity

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RF Attenuators

Design T-pad and Pi-pad attenuator networks
Attenuator Types:
  • Pi: Shunt-series-shunt resistor network
  • T: Series-shunt-series resistor network
  • Bridged-T: Improved bandwidth
Inputs:
  • Attenuation (dB)
  • Input impedance (typically 50Ω)
  • Output impedance (typically 50Ω)
Outputs:
  • R1, R2, R3 resistor values
  • Standard value substitutions
  • Circuit schematic
Pi Configuration:
  R1 (shunt): 150Ω
  R2 (series): 37.4Ω
  R3 (shunt): 150Ω

T Configuration:
  R1 (series): 16.6Ω
  R2 (shunt): 66.9Ω
  R3 (series): 16.6Ω

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Transmission Lines

Calculate impedance for various transmission line types:
Single-ended trace on surface:
  • Trace width
  • Substrate height
  • Dielectric constant (εr)
  • Copper thickness
Result: Impedance (Z₀)
Common Impedances:
  • 50Ω: RF, antenna feeds
  • 75Ω: Video, cable TV
  • 90Ω: USB differential
  • 100Ω: Ethernet, HDMI differential

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Reference Tools

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E-Series Display

Standard resistor and capacitor values reference
Series Coverage:
  • E6: 20% tolerance (6 values per decade)
  • E12: 10% tolerance (12 values)
  • E24: 5% tolerance (24 values)
  • E48: 2% tolerance (48 values)
  • E96: 1% tolerance (96 values)
  • E192: 0.5% tolerance (192 values)
Quick Reference:

E12 Series

10, 12, 15, 18, 22, 27, 33, 39, 47, 56, 68, 82

E24 Series

Plus: 11, 13, 16, 20, 24, 30, 36, 43, 51, 62, 75, 91

Common Values

1k, 10k, 100k (resistors) 0.1µF, 1µF, 10µF (capacitors)

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Color Code

Resistor color code calculator:
ColorDigitMultiplierTolerance
Black0×1-
Brown1×10±1%
Red2×100±2%
Orange3×1k-
Yellow4×10k-
Green5×100k±0.5%
Blue6×1M±0.25%
Violet7×10M±0.1%
Grey8×100M±0.05%
White9×1G-
Gold-×0.1±5%
Silver-×0.01±10%
Mnemonic: “Big Brown Rabbits Often Yield Great Big Vegetable Gardens Weekly”

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Board Classes

IPC standards reference for PCB manufacturing:
  • Consumer products
  • Short product life
  • Function over cosmetics
  • Lowest cost
  • Industrial controls
  • Business machines
  • Extended life expected
  • Moderate reliability
  • Most common class
  • Medical equipment
  • Aerospace/military
  • Continuous performance critical
  • Zero downtime tolerance
  • Highest quality/cost

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Galvanic Corrosion

Reference for metal compatibility to prevent galvanic corrosion
Galvanic Series (anodic to cathodic):
  1. Magnesium (most anodic)
  2. Zinc
  3. Aluminum
  4. Steel
  5. Iron
  6. Tin
  7. Lead
  8. Brass
  9. Copper
  10. Bronze
  11. Stainless Steel
  12. Silver
  13. Gold (most cathodic)
Greater separation in series = higher corrosion risk when in contact

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Usage Tips

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Best Practices

Double-check units: Verify input units (mm vs mils, A vs mA)
Safety margins: Use calculated values as minimums, add safety factor
Standard values: Round calculator results to nearest E-series value
Document assumptions: Note which calculator and settings used

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Common Workflows

1

Power Supply Design

  1. Regulators calculator for voltage
  2. Track width for current paths
  3. Electrical spacing for mains
  4. Via size for ground connections
2

High-Speed Design

  1. Transmission line for impedance
  2. Wavelength for stub lengths
  3. Track width for loss calculation
3

Component Selection

  1. Resistor calculator for dividers
  2. E-series for standard values
  3. Color code for verification

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Keyboard Shortcuts

ActionShortcut
Switch CalculatorCtrl+Tab
Copy ResultCtrl+C
PreferencesCtrl+,
HelpF1
QuitCtrl+Q

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Advanced Features

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Custom Materials

Some calculators allow custom material properties:
  • Dielectric constants
  • Loss tangent
  • Thermal conductivity
  • Resistivity

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Batch Calculations

Most calculators update live as you type, allowing quick “what-if” analysis

PCB Editor

Apply calculations to PCB design

Design Rules

Configure DRC with calculated values

Stack Manager

Design impedance-controlled boards

Component Libraries

Manage component symbols and footprints

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