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Shielding effectiveness calculator
Turn your own before-and-after readings into percentage reduction and dB attenuation.
YOUR TEST RESULTS
Change one thing at a time.
Use the same instrument, mode, position and orientation for before and after readings.
No entries yet. Add a before-and-after pair for one change at a time.
How the numbers are calculated
Percentage reduction = (before − after) ÷ before × 100. Decibel (dB) attenuation uses 10·log₁₀(before ÷ after) for power-density units (µW/m², mW/m²) or 20·log₁₀(before ÷ after) for field-strength units (µT, mG, V/m) — the standard convention for power-like versus amplitude-like quantities. When the baseline or the after-reading is zero, these are left undefined rather than shown as infinite. Readings below an instrument's detection floor should not be entered as a measured zero.