TechTools

Logarithmic Converter

From
To
Sig. figures:

Decibel

dB

3(input)

Neper

Np

0.345388

Bel

B

0.3

Power / Intensity Ratio

P₂/P₁

1.99526

Amplitude / Voltage / Pressure Ratio

A₂/A₁

1.41254

Power Change

% power

99.5262

Amplitude Change

% ampl.

41.2538

Hover any row to copy the value or use it as the new input.

These units carry an absolute reference - use the offset column to convert between them.
dBm

Ref: 1 mW

Power (RF, telecom, audio)

dBW

Ref: 1 W

Power (transmitters, broadcast)

dBµW

Ref: 1 µW

Power (weak signals, receivers)

dBu

Ref: 0.775 V RMS

Voltage (pro audio, 600 Ω)

dBV

Ref: 1 V RMS

Voltage (consumer audio)

dBFS

Ref: Full scale

Digital audio (max = 0 dBFS)

dBSPL

Ref: 20 µPa

Acoustic pressure (hearing threshold)

dBA

Ref: 20 µPa (A-weighted)

Environmental noise

dBZ

Ref: 1 mm⁶/m³

Weather radar reflectivity

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A comprehensive logarithmic unit converter covering all units engineers and scientists use when working with ratios and levels. The relative converter handles Decibel (dB), Neper (Np), Bel (B), linear power ratio, linear amplitude/voltage ratio, percentage power change, and percentage amplitude change - all shown simultaneously. Converting 3 dB instantly shows power ratio ≈ 2, amplitude ratio ≈ 1.414, 0.115 Np, 0.3 B, +100% power, +41.4% amplitude. Accurate math: dB = 10·log₁₀(P₂/P₁) = 20·log₁₀(A₂/A₁); 1 Np = 8.686 dB; 1 B = 10 dB. A built-in absolute dB reference table covers dBm (ref 1 mW), dBW (ref 1 W), dBµW (ref 1 µW), dBu (ref 0.775 V RMS), dBV (ref 1 V RMS), dBFS (digital full scale), dBSPL (ref 20 µPa), dBA (A-weighted), and dBZ (weather radar) with offset relationships shown. A quick-reference table lists the most memorized dB milestones: 3 dB (doubles power), 6 dB (doubles amplitude), 10 dB (10× power), 20 dB (100× power / 10× amplitude), and their negatives. Adjustable significant figures (3–12). One-click copy on every result. 100% browser-based.

How to Use

  1. 1Enter a value in the input field
  2. 2Select your source unit from the From dropdown (dB, Neper, Bel, ratio, or percent)
  3. 3All conversions update instantly across all output units
  4. 4Hover any result row and click Copy to copy that value
  5. 5Click ⇄ to swap the From unit to a different target
  6. 6Use the quantity type selector (field vs power) if working with voltage/pressure vs watt-level quantities

Features

  • Converts between dB, Neper, Bel, linear amplitude ratio, linear power ratio, and percentage change
  • Supports both field quantity (20×log) and power quantity (10×log) conventions
  • Instant reactive conversion - all outputs update as you type
  • Full conversion table showing every unit at once
  • Copy any individual result to clipboard with one click
  • Swap From unit with a single click
  • Common reference values shown for context (0 dB = unity, +3 dB ≈ 2× power, etc.)
  • 100% browser-based - no data sent to any server

Frequently Asked Questions

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