Stem Sum Loudness Estimator
Estimate the loudness of a full mix from dialogue, music and effects stem measurements using uncorrelated power summation.
Stems are largely uncorrelated, so their powers add. A dialogue stem at −27 with music and effects ~3–4 LU below it lands the mix near −24/−25 LUFS — exactly why the '−27 dialog anchor' works for OTT specs. If your M&E is hotter than your dialogue, the mix loudness detaches from the dialog anchor and dialog-gated QC will diverge.
Rule / Formula
Note: Correlated content (e.g. music printed on two stems) adds more than power summation predicts; treat as an estimate.
Estimate the loudness of a full mix from dialogue, music and effects stem measurements using uncorrelated power summation.
About Stem Sum Loudness Estimator
Estimate the loudness of a full mix from dialogue, music and effects stem measurements using uncorrelated power summation. Stems are largely uncorrelated, so their powers add. A dialogue stem at −27 with music and effects ~3–4 LU below it lands the mix near −24/−25 LUFS — exactly why the '−27 dialog anchor' works for OTT specs. If your M&E is hotter than your dialogue, the mix loudness detaches from the dialog anchor and dialog-gated QC will diverge.
How to use Stem Sum Loudness Estimator
- 1Enter your values into the fields in Stem Sum Loudness Estimator.
- 2The result and any pass/fail verdict update instantly as you type — no button to press.
- 3Check the substituted formula and worked example to see exactly how the result was derived.
- 4Copy or note the result for your spec, delivery or planning.
Why use Stem Sum Loudness Estimator?
- ✓Runs entirely in your browser with instant, private results — no data leaves your device.
- ✓Built on a published reference: ITU-R BS.1770-4 (power-domain loudness).
- ✓Shows the governing formula and a worked example, so you can trust and check every result.
- ✓100% free with no sign-up, no watermark and no usage limits.
- ✓Works on any device — desktop, tablet or phone — and keeps working offline once loaded.
Frequently asked questions
What does Stem Sum Loudness Estimator do?+
Estimate the loudness of a full mix from dialogue, music and effects stem measurements using uncorrelated power summation. Stems are largely uncorrelated, so their powers add.
Is my data private?+
Yes. Stem Sum Loudness Estimator runs entirely in your browser — your inputs are never uploaded, stored or logged.
What standard or source is Stem Sum Loudness Estimator based on?+
It follows ITU-R BS.1770-4 (power-domain loudness); Netflix sound-mix practice (dialog anchoring). Always confirm against the current official document, as specifications and rates can change.
What formula does it use?+
Stem Sum Loudness Estimator uses: L_mix ≈ −0.691 + 10·log₁₀(10^((D+0.691)/10) + 10^((M+0.691)/10) + 10^((E+0.691)/10)). The tool shows this formula with your own numbers substituted so you can verify the result.
Is Stem Sum Loudness Estimator free to use?+
Yes — it is completely free with no account, no sign-up and no usage limits. There is no watermark and no paywall.
Embed Stem Sum Loudness Estimator on your website
Want Stem Sum Loudness Estimatoron your own site? Paste this snippet into any HTML page — it's free, with no API key or sign-up. The tool loads in an iframe and keeps working exactly as it does here.
<iframe src="https://tooljolt.com/tools/stem-sum-loudness-estimator" width="100%" height="640" style="border:1px solid #e5e7eb;border-radius:12px;max-width:680px" title="Stem Sum Loudness Estimator — ToolJolt" loading="lazy"></iframe>Related Broadcast tools
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