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dBm to mW Converter & Free Space Path Loss (FSPL) Calculator

Convert RF power between dBm, milliwatts (mW), Watts, and dBW, and calculate Free Space Path Loss (FSPL) attenuation for wireless radio links.

Input Parameters

Try Example:
dBm
-120100
mW
0.00011000
km
0.01500
GHz
0.1100

Calculation Results

Calculation Mode
dbm-to-mw
RF Power Level (dBm)
20 dBm
RF Power in Milliwatts (mW)
100 mW
RF Power in Watts (W)
0.1 Watts
RF Power Level (dBW)
-10 dBW
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Material Requirement Summary (Copy-Ready)
Konversi Daya RF (dBm ke mW) – InfraCalc.web.id
Daya Input : 20 dBm
Hasil mW   : 100 mW
Hasil Watt : 0.1 Watt
Hasil dBW  : -10 dBW
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Technical Accuracy Note: Calculation results are engineering estimates based on standard RFC/IEEE/ITU-T models. Actual field performance may vary due to protocol overhead, hardware specifications, and environmental factors.

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How to Use This Tool

  1. Select your calculation mode: dBm to mW conversion, mW to dBm conversion, or Free Space Path Loss (FSPL).
  2. Input your power value (dBm or mW) or specify wireless link distance (km) and carrier frequency (GHz).
  3. Review the converted power values across dBm, mW, Watts, dBW, or the resulting free-space path loss in dB.

Worked Example: Wi-Fi Transmission 20 dBm (100 mW)

Worked example: An RF power level of 20 dBm equals 100 mW (0.1 Watts / -10 dBW). Standard indoor Wi-Fi access points typically broadcast between 14 and 20 dBm (25 to 100 mW), while high-power outdoor radios can emit 27 to 30 dBm (500 to 1,000 mW).

Example Input
Calculation Mode
Power Conversion: dBm to mW / Watts / dBW
Power Level (dBm)
20 dBm
Calculated Output
Calculation Mode
dbm-to-mw
RF Power Level (dBm)
20 dBm
RF Power in Milliwatts (mW)
100 mW
RF Power in Watts (W)
0.1 Watts
RF Power Level (dBW)
-10 dBW
Material Requirement Summary (Copy-Ready)
Konversi Daya RF (dBm ke mW) – InfraCalc.web.id Daya Input : 20 dBm Hasil mW : 100 mW Hasil Watt : 0.1 Watt Hasil dBW : -10 dBW

Core Concept & Engineering Notes

The decibel-milliwatt (dBm) unit provides an expression of absolute radio frequency and optical power referenced to one milliwatt (1 mW = 0 dBm). In telecommunications and wireless engineering (Wi-Fi, cellular, microwave links, and optical transport), power levels span enormous dynamic ranges—from tens of Watts down to fractions of a picowatt. Expressing these extremes in linear milliwatts or Watts would necessitate cumbersome decimal scientific notation. Converting to a logarithmic decibel scale reduces complex cascading gain and attenuation stages to elementary additions and subtractions. A foundational mental model for RF engineers is the 'Rule of 3s and 10s': an increase of +3 dB doubles linear power in milliwatts (e.g. 10 dBm = 10 mW, so 13 dBm = 20 mW), while a decrease of -3 dB halves power. An increase of +10 dB multiplies linear power by a factor of 10 (20 dBm = 100 mW, 30 dBm = 1,000 mW = 1 Watt), and a +20 dB increase represents a 100-fold power multiplication. Beyond direct power conversions, this calculator implements Free Space Path Loss (FSPL) modeling governed by ITU-R P.525. FSPL quantifies the geometric spreading loss of an electromagnetic wavefront propagating through unobstructed free space. Governed by the inverse-square law, received signal density attenuates proportionally with distance squared and carrier frequency squared, serving as the benchmark foundation for wireless point-to-point link planning.

How It Was Calculated (Formulas & Steps)

Frequently Asked Questions (FAQ)

What is the fundamental difference between dB, dBm, and dBi?

dB (decibel) is a relative dimensionless ratio expressing power gain or loss. dBm is an absolute measurement of power referenced to 1 milliwatt. dBi expresses directional antenna gain relative to a theoretical isotropic antenna radiating equally in all three dimensions.

Why are received Wi-Fi and optical signal strengths almost always negative (-dBm)?

A negative dBm value signifies power less than 1 milliwatt (0 dBm). For example, a Wi-Fi signal of -50 dBm represents 0.00001 mW (10 nanowatts), and a weak -80 dBm signal equals 0.00000001 mW (10 picowatts).

What is the maximum legal Wi-Fi EIRP transmit power in Indonesia per Kominfo regulations?

Under Indonesian SDPPI/Kominfo regulations, the maximum Equivalent Isotropically Radiated Power (EIRP = TX + Antenna Gain - Cable Loss) for 2.4 GHz Wi-Fi is capped at 20 dBm (100 mW). For 5.8 GHz outdoor point-to-point links, legal limits allow up to 36 dBm (4 Watts) for licensed bands.

How can I mentally calculate dBm power without a calculator?

Memorize the baseline: 0 dBm = 1 mW. Adding +10 dBm multiplies by 10. Adding +3 dBm multiplies by 2. Example: 23 dBm = 0 + 10 + 10 + 3 dBm = 1 mW × 10 × 10 × 2 = 200 mW.

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References & Notes

Last updated: Technically Verified · Industry Standard

Note: Results above are mathematical estimates based on standard formulas. Always verify against official vendor documentation and site conditions before production deployment.

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🔬 Scientific Methodology & Normative Verification

Engineering Sensitivity Analysis, Response Curve & Technical Citation

✓ Calibrated to ISO/IEC/IEEE/TIA Clauses

1. 1. 3-Point Engineering Sensitivity & Tolerance Envelope

Comparative evaluation across theoretical laboratory bounds (0% loss), current nominal operating point, and conservative field safety bounds (±15% thermal/aging derating).

Evaluated Parameter Ideal Theoretical Bound Nominal Operating Point Conservative Safety Bound (±15%) Engineering Derating Rule
RF Power Level (dBm) 18 20 23 Engineering Safety Margin (+15% Overhead)
RF Power in Milliwatts (mW) 90 100 115 Engineering Safety Margin (+15% Overhead)
RF Power in Watts (W) 0.09 0.1 0.11 Engineering Safety Margin (+15% Overhead)
RF Power Level (dBW) -9 -10 -11.5 Engineering Safety Margin (+15% Overhead)

2. 2. Mathematical Function Curve & Operating Coordinate (x₀, y₀)

MATHEMATICAL RESPONSE CURVE: RF POWER LEVEL (DBM) VS RF POWER LEVEL (DBM) Conservative Engineering Bound (+15% Safety Margin) 8 12 16 20 24 28 32 (x₀=20, y₀=20) Variabel Independen (x): RF Power Level (dBm)

3. 3. Physical Constants & Normative Standard Clauses

R_loop(Cat6, 20°C) = 14 Ω/100m ANSI/TIA-568.2-D & IEEE 802.3bt

DC Loop Resistance for 23 AWG Solid Copper Cat6

Clause 6.4.1 / Table 145-1 — Nominal 23 AWG solid copper loop resistance at 20°C is 14.0 Ω/100m (TIA maximum ceiling is 18.8 Ω/100m).

α_opt(1490nm) = 0.25 dB/km ITU-T Rec. G.652.D & G.984.2

Single-Mode Optical Fiber Attenuation Coefficient at 1490 nm

Table 1 / Class B+ & C+ Optical Path — Typical G.652.D attenuation at 1490 nm downstream is 0.22–0.25 dB/km (1310 nm upstream: 0.35 dB/km).

α_Cu(20°C) = 0.00393 °C⁻¹ IEC 60028

Temperature Coefficient of Resistance for Copper

International Annealed Copper Standard — Used in thermal derating equation: R(T) = R_20 × [1 + 0.00393 × (T - 20)].

4. 4. Independent Technical & Academic Citation (IEEE / APA 7th / BibTeX / LaTeX)

Use the standard citation formats below to reference this computational methodology in engineering specifications, audit reports, or academic papers.

Format IEEE & APA 7th Edition

[IEEE] KalkuNet Engineering Team, "dBm to mW Converter & Free Space Path Loss (FSPL) Calculator — Standard Engineering Computational Instrument," KalkuNet Technical Suite, 2026. [Online]. Available: https://kalkunet.com/en/tools/dbm-converter. [Accessed: 2026-11-08].

[APA 7th] KalkuNet Engineering Team. (2026). dBm to mW Converter & Free Space Path Loss (FSPL) Calculator (Production release 2026-11-08) [Engineering computational software]. KalkuNet. https://kalkunet.com/en/tools/dbm-converter

BibTeX & LaTeX Derivation Snippet
@software{kalkunet_dbm_converter_2026,
  author = {{KalkuNet Engineering Team}},
  title = {{dBm to mW Converter & Free Space Path Loss (FSPL) Calculator --- KalkuNet Engineering Suite}},
  year = {2026},
  publisher = {KalkuNet.com},
  url = {https://kalkunet.com/en/tools/dbm-converter},
  urldate = {2026-11-08}
}

% LaTeX Engineering Derivation — Generated via https://kalkunet.com/en/tools/dbm-converter
\begin{equation}
  \text{Model: } mW to dBm = 10 × log10(Power mW)
\end{equation}
% Parameter Input Terukur: mode = dbm-to-mw, \; powerDbm = 20, \; powerMw = 100, \; distanceKm = 5
% Hasil Evaluasi Numerik : mode = \mathbf{dbm-to-mw}, \; powerDbm = \mathbf{20}, \; powerMw = \mathbf{100}