Crosstalk Calculator

Calculate crosstalk between two signal channels: enter the source (aggressor) and coupled (victim) voltage levels to get the crosstalk in decibels, percent coupling, isolation, and attenuation ratio.

Quick Facts

Formula
XT(dB) = 20 × log10(Vcoupled / Vsource)
The standard voltage-ratio definition of crosstalk. Every 20 dB drop means the coupled voltage is 10 times smaller; isolation is simply -XT.

Your Results

Calculated
Crosstalk
-
20 × log10(coupled / source), in dB
Channel isolation
-
-Crosstalk; higher means better separation
Coupling ratio
-
Coupled voltage as a percent of source
Attenuation ratio
-
How many times larger the source is

Ready

Enter the source and coupled signal levels, then press Calculate.

Understanding Crosstalk

Crosstalk is the unwanted coupling of a signal from one channel (the aggressor or source) into a nearby channel (the victim), where it shows up as interference. It happens in audio cables, telecom wiring, PCB traces, and any pair of conductors placed close enough to interact capacitively or inductively. Engineers quantify how much unwanted signal has leaked across by comparing the coupled level to the original source level, expressed on a logarithmic decibel (dB) scale because the leaked signal is usually thousands of times smaller than the source.

The formula

The standard voltage-ratio definition of crosstalk (XT) is:

  • Crosstalk (dB): XT = 20 × log10(Vcoupled / Vsource), where Vsource is the level driven onto the aggressor channel and Vcoupled is the unwanted level measured on the victim channel.
  • Isolation (dB): the positive mirror of crosstalk, Isolation = -XT. A crosstalk of -60 dB is the same coupling as 60 dB of isolation.
  • Coupling ratio (%): (Vcoupled / Vsource) × 100, the linear fraction of the source that leaked through.
  • Attenuation ratio: Vsource / Vcoupled, how many times larger the source is than the leaked signal (for example, "1 : 1,000" means the coupled voltage is a thousandth of the source).

Common reference points

  • -20 dB — coupled signal is 10% of the source. Very poor isolation; crosstalk would be clearly audible or visible.
  • -40 dB — coupled signal is 1% of the source. Marginal; acceptable for some consumer-grade cabling.
  • -60 dB — coupled signal is 0.1% of the source. A common target for decent line-level audio interconnects.
  • -80 dB — coupled signal is 0.01% of the source. Typical of well-shielded professional cabling and instrumentation.

Reading your result

A more negative crosstalk figure (or a higher isolation figure) always means less interference. Because the scale is logarithmic, every additional 20 dB represents a 10x reduction in the coupled voltage, not a linear improvement — going from -40 dB to -60 dB is a 10x reduction, the same relative improvement as going from -60 dB to -80 dB. Compare your result against a target isolation spec appropriate to the application (consumer audio, professional audio, telecom cabling, or PCB routing) rather than judging the number in isolation.

Frequently Asked Questions

What is the formula for crosstalk?
Crosstalk (XT) expressed as a voltage ratio in decibels is XT(dB) = 20 × log10(Vcoupled / Vsource), where Vsource is the signal level on the driving (aggressor) channel and Vcoupled is the unwanted level picked up on the victim channel. Because Vcoupled is normally much smaller than Vsource, the result is a negative number; more negative means less crosstalk.
What is the difference between crosstalk and isolation?
They describe the same coupling from opposite directions. Isolation is simply the positive magnitude of the crosstalk figure: Isolation(dB) = -XT(dB). A crosstalk of -60 dB and an isolation of 60 dB describe the identical amount of unwanted coupling.
What does a -60 dB crosstalk figure mean in practical terms?
Every 20 dB on this scale corresponds to a factor of 10 in voltage, so -60 dB means the coupled voltage is about 1/1000 (0.1%) of the source voltage. As a rule of thumb, -40 dB or better is considered acceptable for many consumer audio and cable applications, while professional and measurement equipment often targets -80 dB or beyond.
Does this calculator account for cable length or frequency?
No. This tool computes crosstalk from two measured or specified voltage levels using the standard logarithmic ratio formula. Real coupling through capacitance and inductance also depends on frequency, cable length, and geometry, so treat this as the definition-level dB/percentage conversion, not a physical coupling simulation.

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