# Converters & Calculators

## Use the below converter to convert mils to: mm, Oz, um, inch.

Type a value in a field to convert:

mm:

mil:

Type a value in a field to convert:

mil:

Oz:

Type a value in a field to convert:

um:

mil:

Type a value in a field to convert:

inch:

mil:

## Use below calculator to calculate trace width , and via diameter according to requested current:

This Javascript web calculator calculates the resistance, voltage drop, and power loss of printed circuit board vias.

Inputs:

 Finished Hole Dia milmmum Plating Thickness oz/ft^2milmmum Via Length milmmum

Optional Inputs:

 Applied Current Amps Plating Resistivity Ohm-cm

Electrical Results:

 Resistance Ohms Voltage Drop Volts Power Loss Watts Estimated Ampacity Amps

Thermal Results:

 Thermal Resistance Deg. C/Watt

Notes:
Resistance = Resistivity*Length/Area
Area = pi*(Inner_dia + Plating_thk)*Plating_thk
Resistivity = 1.9E-6 Ohm-cm (plated copper)
(plated copper is much more resistive than pure copper)
Copper Thermal_Resistivity = 0.249 cm-K/W (at 300K)
Est_Ampacity [Amps] = k*(Temp_Rise [deg C])^b*(Area [mils^2])^c
For IPC-2221 external layers: k = 0.048, b = 0.44, c = 0.725

Disclaimer:
These calculations are believed to be correct, but not guaranteed. Use at your own risk!

This Javascript web calculator calculates the trace width for printed circuit boards based on a curve fit to IPC-2221 (formerly IPC-D-275).

Inputs:

 Current Amps Thickness oz/ft^2milmmum

Optional Inputs:

 Temperature Rise Deg CF Ambient Temperature Deg CF Trace Length inchfeetmilmmumcmm

Results for Internal Layers:

 Required Trace Width milmmum Resistance Ohms Voltage Drop Volts Power Loss Watts

Results for External Layers in Air:

 Required Trace Width milmmum Resistance Ohms Voltage Drop Volts Power Loss Watts

Notes:

The trace width is calculated as follows:

First, the Area is calculated:

Area[mils^2] = (Current[Amps]/(k*(Temp_Rise[deg. C])^b))^(1/c)

Then, the Width is calculated:

Width[mils] = Area[mils^2]/(Thickness[oz]*1.378[mils/oz])

For IPC-2221 internal layers: k = 0.024, b = 0.44, c = 0.725

For IPC-2221 external layers: k = 0.048, b = 0.44, c = 0.725

where k, b, and c are constants resulting from curve fitting to the IPC-2221 curves

For geometry diagrams, click on the pictures below.  Disclaimer:
These calculations are believed to be correct, but not guaranteed. Use at your own risk! Zeev Jabotinsky St,

Bursa, Ramat-Gan, Israel