Best Free Metering Plugins: 8 Tools for Loudness, Spectrum and Phase

If you want one free meter that covers the most everyday checks, start with Voxengo SPAN. Add Youlean Loudness Meter when delivery loudness and true peak are the question, TDR Prism when you need to see masking or compare a reference, and Voxengo Correlometer when stereo phase is the concern. These tools are not eight versions of the same plugin. Each answers a different monitoring question, and choosing by that question is more useful than filling the master bus with overlapping graphs.

Free metering plugins compared by diagnostic task

Loudness, spectrum, masking and correlation answer different questions

A meter becomes useful only after you can finish the sentence: “I need to know whether…” A loudness meter can show program loudness and true peak, but it cannot explain a harsh upper midrange. A spectrum analyzer can show where energy accumulates, but it cannot decide whether that energy belongs there. A correlation meter can warn about possible mono loss, but a positive reading is not a quality certificate.

1. Youlean Loudness Meter: start here for loudness and true peak

Youlean is the clearest first addition when the destination gives you a loudness or true-peak requirement. The current Youlean product page describes loudness, loudness range, dynamics and true-peak measurement and lists Windows and macOS application, VST2, VST3, AU and AAX options.

The free edition includes integrated loudness, true peak, loudness range, PLR and DR readouts, plus loudness and true-peak graphs. It supports mono, stereo and 5.1 audio and does not expire. I would start there for delivery checks. Pro adds streaming presets, a dynamics graph, PDF/PNG/SVG exports, custom presets, A/B states and drag-and-drop analysis; you do not need those extras just to read integrated loudness and true peak.

2. Voxengo SPAN: the most useful general-purpose starting point

SPAN is my default recommendation when someone asks for “a free meter” but has not yet narrowed the problem. According to the official SPAN page, it combines an FFT spectrum analyzer with stereo, mono and mid-side views, level statistics, true-peak clipping detection, EBU R128/K-system metering and stereo correlation. That breadth makes it a sensible first diagnostic panel.

The advantage is consolidation: one plugin can reveal a low-frequency concentration, a clipping concern and a suspicious correlation reading without opening three windows. The danger is assuming one window gives one answer. Read each section independently and follow the clue with the relevant listening or mono check.

3. TDR Prism: best for masking and reference comparison

Prism earns its place because it asks a more useful question than “what does the spectrum look like?” The TDR Prism documentation describes perceptual weighting, human auditory filters, real-time masking indication and comparison between regular inputs, sidechains, audio files and other Prism instances. That makes it especially relevant when two sources compete or a reference seems different but the cause is unclear.

Reference comparison still needs level discipline. A louder reference often appears fuller and clearer before any spectral judgment begins. Prism can show the difference; it cannot remove the bias created by mismatched playback level or tell you whether an arrangement should leave more space.

4. TBProAudio dpMeter5: best for dynamics and dialog-oriented readings

dpMeter5 is the stronger choice when the question includes RMS, crest factor or dialog-gated measurements rather than only integrated loudness. The current dpMeter product page lists RMS, EBU R 128 and DIAL modes, along with integrated, momentary, peak, true-peak, loudness-range and crest readings.

For dialog work, check the session sample rate first: the dpMeter5 manual limits DIAL measurements to 44.1 and 48 kHz. This restriction applies to DIAL mode, not to every measurement in the plugin. Choose a dialog-gated reading only when your delivery requirement calls for it; a music mix and a dialogue program may need different measurements.

5. MeldaProduction MAnalyzer: detailed spectrum work with a free-tier caveat

MAnalyzer is a broad spectral tool for readers who want more than a simple curve. The official MAnalyzer page documents smoothing, normalization, super-resolution, prefiltering and deharmonization, along with spectrum analysis and integrated peak and loudness meters. Sonogram access requires the paid MFreeFXBundle upgrade.

Two limits matter. First, Melda’s page still describes its loudness meter as EBU R128 and ITU-R BS.1770-3 compliant, so that is the revision to report. Second, the MFreeFXBundle comparison says paid activation adds resizing, preset management and sonogram access in analyzers and equalizers. Do not assume the product headline means every displayed feature is available without the upgrade.

6. Blue Cat FreqAnalyst: a simpler real-time spectrum view

FreqAnalyst fits the opposite preference: a focused spectrum display without the broader metering stack. Blue Cat describes the free FreqAnalyst as a mono and stereo real-time spectrum analyzer with control over frequency transformation, smoothing, zoom and thresholds, available for Mac and Windows in common plugin formats.

The same page clearly separates the Pro edition. Saving and restoring curves, precise measurement tools, a 3D spectrogram and related advanced functions are not safe claims for the freeware version. If your question is simply “where is the energy?”, that limitation may be useful: fewer controls can make the first diagnosis faster.

7. HOFA 4U Meter, Fader & MS-Pan: quick level and M/S checks

HOFA’s 4U utility is useful when you want a compact channel tool rather than another large graph. The current HOFA freeware page describes peak and hold metering, EBU readings, loudness range, M/S encode/decode, stereo/mono switching and drag-and-drop file analysis.

The page lists Audio Unit, VST, VST3 and AAX formats and retains both 32- and 64-bit DAW wording. Treat that as a reason to check the actual installer for your current OS and host before planning a session around it. The feature fit is clear; the compatibility sentence should stay cautious.

8. Voxengo Correlometer: best for multiband stereo correlation

Correlometer is the specialist in this group. The official Correlometer page documents correlation metering across 4 to 64 bands, phase-issue detection, mono-compatibility checking and sidechain support. A broadband meter may look acceptable while a narrower frequency region cancels; the multiband view is designed to expose that distinction.

Correlation remains a clue, not a verdict. Negative or unstable bands deserve a mono sum and a routing check, but the display does not tell you whether the cause is an intended stereo effect, a polarity error, a timing offset or a harmless local feature. Diagnose the cause before narrowing the entire mix.

What the loudness standards do—and do not—tell you

ITU-R BS.1770-5 defines algorithms for measuring program loudness and true-peak audio level. EBU R 128-2023 uses program loudness for broadcast normalization, maximum true peak for the upper technical limit, and loudness range plus momentary and short-term measures to further characterize a program.

Those documents explain the measurement framework; they do not create one universal target for music, podcasts, broadcast and every streaming platform. Use the destination’s current rules. SoundForgePro keeps the changing delivery details in the separate streaming loudness standards guide and podcast loudness guide. If you are working specifically inside Sound Forge, the Sound Forge loudness-meter walkthrough covers that software-specific path.

A practical two-meter workflow

For a delivery check, establish the destination’s current loudness and true-peak requirements before choosing a meter or changing the audio. A preset is a convenience, not a substitute for those requirements.

1. Name the failure you are checking.Clipping, delivery loudness, tonal buildup, masking and mono loss are different failures.
2. Choose one primary meter.Use Youlean or dpMeter5 for delivery and dynamics, SPAN or FreqAnalyst for spectrum, Prism for masking, or Correlometer for phase.
3. Add one secondary view only when it changes the decision.For example, pair a loudness meter with SPAN, or Prism with Correlometer. Avoid three spectrum analyzers showing the same clue.
4. Confirm the graph with an audible check.Level-match references, sum to mono when phase is the issue, and bypass processing before accepting the meter’s implication.
5. Verify the final delivery readings.For delivery work, compare the final readings with the requirements you established at the start.

Which free meter should you download?

The useful free-meter setup is usually smaller than the download list. Pick the question, choose one tool that answers it, and add a second meter only when it covers a different problem. That keeps the screen readable and makes every measurement lead to a decision.