Office Pod STC Rating: How to Calculate It in 2026

Office pod spec sheets throw around dB reduction numbers, but buyers keep asking for an STC rating that most pod manufacturers don't publish — this guide shows you how to translate one into the other and calculate what you actually need.

Why this matters

STC (Sound Transmission Class) was built for walls, doors, and floor assemblies under ASTM E90 — it's a single number averaged across 16 frequency bands, and it assumes the sound source and receiver sit in fixed rooms on either side of a permanent partition. A standalone office pod isn't a wall. It's a sealed enclosure with a door, a ventilation gap, and glass panels, so testing houses use ISO 23351-1:2020 instead, which measures actual dB(A) reduction of speech and ambient noise entering or leaving the enclosure.

Asking a pod vendor for their STC rating is like asking a car for its horsepower and getting quoted torque — related, not identical, and the mismatch causes real buying mistakes. Get the calculation wrong in 2026 and you either overspend on an 8-person meeting booth for a solo call booth job, or you install a pod that still leaks enough noise to make confidential HR conversations audible three desks away.

What you'll need

• A sound level meter or a calibrated phone app (NIOSH SLM or similar) that reads dB(A)
• Five minutes to record ambient noise at the install location during a normal work period
• The manufacturer's ISO 23351-1:2020 test data or published dB reduction spec
• A defined use case: private calls, confidential HR meetings, focus work, or client-facing video calls
• Floor plan measurements if you're comparing a solo booth against a larger 2-person meeting booth

The steps

1. Measure your baseline ambient noise

Stand at the exact spot where the pod will go and record dB(A) for at least two minutes during peak office hours, not during a quiet lunch lull. Open-plan floors with active call centers or sales teams typically run 60-65 dB(A); a quieter admin floor sits closer to 50-55 dB(A). This baseline is the number every other calculation depends on, so skipping it is the single most common mistake in pod sizing.

Common mistake: measuring at 9am before the floor fills up, then buying a pod sized for a noise level that doesn't exist by 11am.

2. Define the target noise level for your use case

Different tasks need different quiet. Confidential HR reviews and legal calls want 35-40 dB(A) — roughly library-quiet, where speech from outside the pod is unintelligible. Focus work for deep concentration can tolerate a bit more, around 40-45 dB(A). Video calls need enough reduction that the microphone doesn't pick up neighboring conversations, which usually lands in the same 35-40 dB(A) band.

Write this number down before you look at a single product page. Buyers who skip this step end up comparing pods on price instead of performance, which is how a solo phone booth ends up doing a job it was never rated for.

3. Calculate the reduction gap

Subtract your target from your baseline: a 65 dB(A) open floor with a 35 dB(A) target needs 30 dB of noise reduction. This single subtraction is the entire calculation — no complicated formula, no frequency-weighting math you need to do by hand, because the ISO 23351-1:2020 test already accounts for the frequency spread that STC handles separately.

A pod rated at 30-35 dB noise reduction, tested to that ISO standard, closes exactly this gap. That's the range the Quell Office Pod Solo is built around, which is why it's specced for private calls and focus work rather than trading-floor-adjacent placements where ambient noise runs higher.

4. Understand why STC and dB reduction aren't interchangeable

STC ratings on office partition walls commonly land in the 30-35 range for standard drywall assemblies, which looks like it matches a pod's 30-35 dB reduction spec — but the test conditions differ enough that treating them as equivalent will misprice your decision. STC assumes a continuous wall between two fixed rooms; pod dB reduction accounts for the door seal, glass panel, and ventilation path all at once, which is the actual noise path in a real office.

If a vendor quotes you an STC number for a standalone pod without ISO 23351-1:2020 backing, ask what test method produced it. A number without a standard behind it isn't comparable to anything.

5. Match the gap to a tested pod, not a marketing number

Once you know your reduction gap, shop against ISO 23351-1:2020 test data specifically, not a vague "soundproof" claim. A 30 dB gap needs a pod tested at 30 dB or higher under real conditions, door closed, ventilation running. Pods with published test certificates give you a number you can defend to a facilities director; pods without one give you a guess.

Common mistake: buying based on wall thickness or glass thickness alone. Panel thickness correlates loosely with performance but isn't the test — the sealed assembly's tested reduction is.

6. Account for real-world loss after install

A rated 30 dB reduction assumes the door is fully closed and the seals are intact. In practice, a pod with the door cracked, ventilation left wide open, or installed against a wall with its own acoustic issues will underperform its rating by several dB. Budget for this by choosing a pod rated slightly above your calculated gap rather than exactly at it — if your gap is 28 dB, don't buy a pod rated at exactly 28 dB with no margin.

7. Re-measure after installation

Once the pod is in place, take a second dB(A) reading from inside with the door closed and someone talking at normal volume outside. Compare it against your target. If it's off by more than 3-5 dB, the gap is almost always a seal, vent, or placement issue rather than a manufacturing defect.

Troubleshooting

• Measured reduction is 5+ dB below spec: check door seal compression and confirm the door is latching fully, not just resting closed.
• Pod performs worse near one wall than another: the adjacent wall may be reflecting or transmitting sound differently; reposition if the floor plan allows it.
• Vendor won't provide ISO 23351-1:2020 data, only an STC number: treat that STC figure as unverifiable for a standalone enclosure and ask for the actual test report.
• Noise reduction feels adequate for speech but video calls still pick up background chatter: the issue is usually microphone gain, not pod performance — check mic placement before blaming the enclosure.
• Ambient office noise has grown since your original measurement: re-measure. Offices that added headcount in 2026 often see baseline noise climb 5-8 dB(A) from prior years, which can push a previously adequate pod below its target.
• Comparing two brands' "soundproof" claims with no shared standard: insist both quote ISO 23351-1:2020 or walk away from the comparison entirely.

Tools and resources

• Sound level meter app calibrated to dB(A) weighting
• ISO 23351-1:2020 test documentation from your shortlisted vendors
• 2-person meeting booth spec sheet, useful as a benchmark for multi-person reduction comparisons
• Floor plan or facilities drawing showing HVAC and wall proximity at the install site

Pods with published ISO 23351-1:2020 ratings

Quell Office Pod Solo

1-person soundproof phone booth for private calls and focus work.

£5,124.50

Office Phone Booth Quell - 2 Person

Soundproof freestanding enclosure for two people to hold private meetings.

£7,034.50

Office Phone Booth Folio

Soundproof booth for one person taking private calls or Zoom meetings.

£3,945

What to do next

Once you've calculated your reduction gap, the next decision is capacity, not just acoustics — a 30 dB rating means nothing if the pod is the wrong size for how many people actually need to use it. Work through how to choose office pod size next to pair your acoustic target with the right footprint.

FAQ

One last thing

The gap between a rated 30 dB reduction and what a pod delivers on day one is almost always the door seal, not the panel material — check that first if a newly installed pod feels louder than its spec sheet promised.

Related guides

• How to choose office pod size
• How to reduce noise bleed between office meeting pods
• How to install a soundproof office pod