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Electrical calculator

dBm to Watts Calculator

Convert dBm ↔ watts and dBm ↔ milliwatts with hard validation. Canonical Unit Engine for RF power.

Instant result
Result
—

Enter values to calculate.

Inputs—
Mode—
Formula—
Trust summary CVP VERIFIED · CVP protocol 1.0.0-proposed · Engineering assurance
Input interpretation
Enter values to calculate.
Result
—
Assurance
Engineering
Declared partition coverage
PASS · 5/5 declared partitions (dbm-w, w-dbm, dbm-mw, mw-dbm, invalid-domain) · Matrix
Known limitations
  • RF power unit conversion (dBm ↔ W and dBm ↔ mW). Not a dBW / dBµV converter.
  • Core CVP does not include live graph, viewport, or pointer interaction.
Model
dBm ↔ W / mW
Scope
Log power vs 1 mW (dBm), not 1 W (dBW)
Verification
Engine tested · Source checked · v1.3.1 · CVP VERIFIED · CVP protocol 1.0.0-proposed · Engineering assurance· View Manifest · CVP overview · Specification
Versions
Calculation 1.3.1 · CVP protocol 1.0.0-proposed · Evidence 2026-09-13.overflow-ssr-rollout
Verification revision
2026-09-13.overflow-ssr-rollout · 2/2 property · digest 250f2cc95400
Legacy regression
22/22 tests · Production surface contract 4/4
Trust layers
Verification VERIFIED · Production CURRENT · overall VERIFIED
Reference
O1 model · O2 expected_values · O2 numerical_behavior
Interfaces
PASS · UI (SSR) / REST / MCP — ui-ssr is query-result HTML, not a live browser session. Error-path engine·REST·MCP 5/5 (status, code, calculation_version). SSR compared on URL-canonical requested calculations; empty query is idle (not an error) and JSON-typed object/array inputs are REST/MCP-only. Public share URLs use UI alias `a` plus `mode`. Canonical Agent/API field is `value`; mode defaults to dbm-w.
Supplemental domain review
Internal · Pass · electrical-engineer
Named expert review
Not performed
CVP suite
6/6 golden · 8/8 CVP boundary · 14/14 invalid · 2/2 property · 4/4 metamorphic · 4/4 round-trip · 10/10 cross-interface · 4/4 CVP contract · Manifest
Sources
Sources
Evidence
9 legacy golden · 7 legacy boundary · legacy regression suite · 6/6 oracle-backed golden · 14/14 invalid · Artifact integrity PASS · CalculatorX electrical review
This calculator CURRENT · Public schema 1.3.1 matches · Semantic contract ✓ · Production attested · Public/cache ✓ · Origin ✓
Semantic contract
PASS
Full verification

Manifest identity, reference classes, interfaces, suite, and production records.

Formulas

Core equations used by this calculator.

dBm → WW = 10^((dBm − 30)/10)
W → dBmdBm = 10·log10(W) + 30
dBm → mWmW = 10^(dBm/10)
mW → dBmdBm = 10·log10(mW)
iReverse log requires power > 0. IEEE-754 binary64 range applies. 0 dBm = 1 mW = 0.001 W; 30 dBm = 1 W.

How to use

1

Choose the conversion direction

Four modes: dBm → W, W → dBm, dBm → mW, and mW → dBm.

2

Enter the value

Watts and milliwatts must be greater than zero for the reverse log. dBm may be negative.

3

Read the converted power or level

W = 10^((dBm−30)/10) and mW = 10^(dBm/10). Adding 10 dB multiplies linear power by 10.

Example calculations

Common configurations with formula and result.

ϟ

−30 dBm

1 µW

10^((−30−30)/10)
1×10⁻⁶ W
ϟ

0 dBm

1 mW reference

10^(0/10)
1 mW = 0.001 W
ϟ

10 dBm

10 mW

10^(10/10)
10 mW
ϟ

30 dBm

0 dBW relative to 1 W

10^((30-30)/10)
1 W
ϟ

40 dBm

10 W

10^((40-30)/10)
10 W

dBm to Watts calculator specification

Version 1.3.1 · Engine tested · Supplemental domain review · Internal · 2026-09-13

Calculation status

Review policy · Evidence · Reviewed by CalculatorX electrical review (electrical-engineer)

Definition
dBm is decibels relative to 1 mW. W = 10^((dBm−30)/10); mW = 10^(dBm/10).
What it calculates
dBm ↔ W / mW
Inputs
  • mode (default dbm-w)
  • value
Outputs
  • number
Formula
W=10^((dBm-30)/10); mW=10^(dBm/10)
Assumptions
  • Log power vs 1 mW (dBm), not 1 W (dBW)
Units
  • dBm, W, mW
Boundary conditions
  • W/mW ≤0 → VALUE_MUST_BE_POSITIVE
  • Bad mode → INVALID_MODE
  • binary64 overflow → NUMERIC_OVERFLOW
  • binary64 underflow to 0 → NUMERIC_UNDERFLOW
Example
30 dBm → 1 W; 0 dBm → 1 mW; −30 dBm → 1 µW
Validation cases

3 published on this page · 22/22 tests · Production surface contract 4/4 · View evidence

  • dbm-w 30 → 1 W
  • dbm-mw 0 → 1 mW
  • dbm-w -30 → 1e-6 W
Sources
  • NIST Technical Note 1850 — Appendix B — dBm ↔ milliwatt · accessed 2026-09-12
    Supports: P_mW = 10^(dBm/10); dBm = 10 log10(P_mW)
  • ITU / RF practice — dBm — 0 dBm = 1 mW
    Supports: Log power ratio definition relative to 1 mW
Last reviewed
2026-09-13
Reviewed by
CalculatorX electrical review (electrical-engineer)
Calculation version
1.3.1

Background

Interpretation and common distinctions.

Convert dBm ↔ watts / milliwatts (Unit Engine).

Canonical engineering / Agent calculator: this page. Lightweight SEO converter sibling: /convert/power/dbm-to-watt.

Agent / API notes

Capability id: units.rf.dbm_watts · tool id: dbm-watt · pin 1.3.1.

Canonical input field is value; share URLs may use the UI alias a. mode defaults to dbm-w.

Other calculators in this family: Antenna Length Calculator, Cascaded Noise Figure Calculator, Coax Impedance Calculator, Free-Space Path Loss Calculator, L-section LC Match Calculator, Receiver Sensitivity Calculator, Reflection Coefficient to Impedance Calculator, RF Link Budget Calculator . Explore all RF & Microwave.

→ Antenna Length Calculator Compute dipole (λ/2) or monopole (λ/4) antenna length from frequency and an empirical length factor. Runs locally in your browser. › → Cascaded Noise Figure Calculator Compute cascaded noise figure and total gain for a multi-stage RF chain using the Friis formula. Add, remove, or reorder stages. Runs locally in your browser. › → Coax Impedance Calculator Compute coaxial characteristic impedance Z0 from shield inner diameter D, center-conductor diameter d, and dielectric εr. Ideal TEM, μr≈1. Runs locally in your browser. › → Free-Space Path Loss Calculator Compute free-space path loss FSPL = 20·log10(d·f) + 20·log10(4π/c) from distance and frequency, with optional antenna gains. Runs locally in your browser. › → L-section LC Match Calculator Narrowband real RL→Z0 L-section match with dual LP/HP solutions. Runs locally in your browser. › → Receiver Sensitivity Calculator Estimate MDS: S = −174 + NF + 10·log10(BW) + SNR_min (dBm). Runs locally in your browser. › → Reflection Coefficient to Impedance Calculator Convert complex Γ ↔ normalized z (Cartesian or polar Γ). Reports VSWR and return loss. Runs locally in your browser. › → RF Link Budget Calculator Compute RF link budget: FSPL, path loss with antenna gains and misc loss, received power, and optional margin above sensitivity. Extends Free-Space Path Loss. ›
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Frequently asked questions

Key distinctions behind the calculation.

Why is 0 W rejected?

log10(0) is undefined; the API returns VALUE_MUST_BE_POSITIVE.

What happens at extreme dBm?

IEEE-754 binary64 representable range applies. Overflow returns NUMERIC_OVERFLOW; a mathematically positive power that underflows to 0 returns NUMERIC_UNDERFLOW. Normal RF values are unaffected.

What if I omit mode?

The engine and schema default to dbm-w (dBm → watts).