Oscilloscope probe loading calculator

Estimate how much signal you lose at the test point when you connect a probe.

Use the resistance seen looking back into the circuit from the test point, with the probe disconnected. The 50 Ω default is an example.

Probe input at the tip

For your own probe, use the input values specified for the probe and oscilloscope combination.

— signal amplitude reduction

Calculation details
Probe impedance magnitude
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Capacitive reactance magnitude
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Phase lag at the test point
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The estimate uses a resistive source and the probe’s input resistance and capacitance in parallel. It leaves out probe bandwidth, ground-lead inductance and any reactive source impedance.