Power conversion

Milliwatts to dBm conversion

Convert milliwatts (mW) to dBm. Formula: dBm = 10 × log10(P_mW). Works offline-ready. Runs locally in your browser. Free online tool — no sign-up.

Instant result

Result

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Enter values to convert.

Inputs —

Mode —

Formula —

Formulas

Core equations used by this converter.

FormuladBm = 10 × log10(P_mW)

iFollow the formulas shown. Calculation runs locally in your browser.

How to use

Take power in milliwatts (must be > 0).

Take common log, multiply by 10.

Result is dBm.

Example conversions

Common values with formula and result.

1 mW to dBm

10 × log10(1) = 0 dBm

0 dBm

10 mW to dBm

10 × log10(10) = 10 dBm

10 dBm

100 mW to dBm

10 × log10(100) = 20 dBm

20 dBm

0.1 mW to dBm

10 × log10(0.1) = −10 dBm

−10 dBm

Milliwatts to dBm conversion specification

Version 1.1.0 · Engine tested

Calculation status

Engine tested 4 published cases
Named expert review Not performed
Calculation version 1.1.0

Review policy

Definition: **mW** — linear power. **dBm** — 10 × log₁₀ of power in milliwatts.
What it calculates: Convert milliwatts (mW) to dBm. Formula: dBm = 10 × log10(P_mW). 1 mW = 0 dBm. Examples and chart.
Inputs: Values required by the selected conversion mode
Outputs: Converted result in the target unit or format
Formula: dBm = 10 × log10(P_mW)
Milliwatts to dBm conversion table: Milliwatts (mW) dBm
0.001 −30
0.01 −20
0.1 −10
1 0
2 ≈3
10 10
20 ≈13
100 20
1,000 30
10,000 40
Assumptions: Conversion runs locally in the browser; values are not uploaded.
Uses the formulas documented on this page.
Units: Formula
Boundary conditions: Empty or invalid input yields no valid result.
Out-of-range values may be rejected by the tool runtime.
Example: 1 mW to dBm → 0 dBm
Validation cases: 1 mW to dBm → 0 dBm
10 mW to dBm → 10 dBm
100 mW to dBm → 20 dBm
0.1 mW to dBm → −10 dBm
Sources: CalculatorX converter runtime
Standard unit / encoding definitions where applicable
Calculation version: 1.1.0

Milliwatts (mW)	dBm
0.001	−30
0.01	−20
0.1	−10
1	0
2	≈3
10	10
20	≈13
100	20
1,000	30
10,000	40

Background

Interpretation and common distinctions.

Use the converter tabs to switch direction when available. Results for Milliwatts to dBm conversion update locally in your browser.

Frequently asked questions

Key distinctions behind the conversion.

How do you convert using Milliwatts to dBm conversion?

Use dBm = 10 × log10(P_mW). Example: 1 mW to dBm → 0 dBm.

Can I switch direction?

Open the related reverse converter listed under Related tools.

Does this run online or locally?

Calculation runs locally in your browser. Values are not uploaded.

How precise are the results?

Results follow the formulas on this page. Round to the precision your use case needs.