Home Studio RT60 Calculator — Free Tool for Podcasters, YouTubers, and Music Producers

A 3.5 m x 3 m x 2.5 m bedroom — the most common home studio size — has an untreated RT60 of 0.70 to 0.95 seconds, depending on whether the floor is carpeted or hardwood. The target for a podcast recording room is 0.20 to 0.30 seconds. That gap — 0.40 to 0.75 seconds of excess reverberation — is the difference between audio that sounds professional and audio that sounds like it was recorded in a bathroom. Closing that gap requires knowing exactly how much absorption your room needs, at which frequencies, and where to place it. That is what the free studio RT60 calculator tells you.

Why Studio RT60 Targets Are Different from Every Other Room Type

Commercial acoustic design targets RT60 values between 0.4 and 0.8 seconds for most room types — offices, classrooms, healthcare spaces. Studios are different because the acoustic goal is fundamentally different.

In an office or classroom, the goal is speech intelligibility: listeners need to understand the speaker. A moderate amount of reverberation (0.4–0.6 s) actually helps intelligibility by reinforcing the direct sound with early reflections. Too little reverberation makes a room feel uncomfortably dead and fatiguing for extended conversation.

In a recording studio, the goal is signal capture: the microphone needs to capture the source (voice, instrument) with minimal room coloration. Any reverberation that the microphone picks up becomes part of the recording and cannot be removed in post-production. Reverb can always be added digitally — it cannot be subtracted. This is why studios target the shortest practical RT60: 0.15–0.40 seconds, depending on the room's function.

Target RT60 by Studio Type

These targets refer to broadband RT60 — the average of the 500 Hz and 1000 Hz octave band values, consistent with ISO 3382-2:2008 §4.2. But for studios, the low-frequency RT60 (125 Hz and 250 Hz) matters just as much, because bass buildup is the most common acoustic problem in small rooms and the hardest to treat.

The Small Room Problem: Modal Resonance

Studio acoustics are fundamentally different from large-room acoustics because of room modes. In a rectangular room, standing waves form at frequencies where the room dimension equals a half-wavelength (or multiple thereof). These are the room's axial modes, calculated as:

f = c / (2L) for the fundamental mode along dimension L

For a 3.5 m room length, the fundamental axial mode is:

f = 343 / (2 x 3.5) = 49 Hz

The first several axial modes for a 3.5 m x 3 m x 2.5 m room:

Below approximately 200 Hz, this room has dense modal activity. The Schroeder frequency — the transition point between modal and statistical behaviour — is:

f_s = 2000 x sqrt(T60 / V)

For an untreated room (T60 = 0.80 s, V = 26.25 m³):

f_s = 2000 x sqrt(0.80 / 26.25) = 2000 x 0.175 = 349 Hz

This means that below 349 Hz, the statistical reverberation formulas (Sabine, Eyring) are unreliable. The sound field is not diffuse — it is dominated by individual room modes that create frequency-dependent peaks and nulls at different positions in the room. An RT60 prediction at 125 Hz using the Sabine equation might say 1.2 seconds, but the actual decay at 125 Hz depends on where you are in the room relative to the mode pattern.

This is precisely why the calculator shows RT60 at all six octave bands and flags the Schroeder frequency. At frequencies below the Schroeder frequency, the RT60 prediction should be treated as an estimate, and the actual acoustic behaviour will vary with listener position.

Worked Example: 3.5m x 3m x 2.5m Podcast Room

Let us calculate the RT60 of a typical spare bedroom converted to a podcast studio, in its untreated state and then with progressively more treatment.

Room Geometry

• Length: 3.5 m, Width: 3.0 m, Height: 2.5 m
• Volume: V = 3.5 x 3 x 2.5 = 26.25 m³
• Floor: 3.5 x 3 = 10.5 m²
• Ceiling: 3.5 x 3 = 10.5 m²
• Long walls: 2 x (3.5 x 2.5) = 17.5 m²
• Short walls: 2 x (3.0 x 2.5) = 15.0 m²
• Total surface area: S = 10.5 + 10.5 + 17.5 + 15.0 = 53.5 m²

Scenario 1: Untreated Room

Total absorption at 1000 Hz:

Floor: 10.5 x 0.30 = 3.15 Ceiling: 10.5 x 0.04 = 0.42 Walls: 32.5 x 0.04 = 1.30 A(1000) = 4.87 m² Sabine

alpha_bar = 4.87 / 53.5 = 0.091

Using Sabine (alpha_bar < 0.20): T60(1000 Hz) = 0.161 x 26.25 / 4.87 = 4.23 / 4.87 = 0.87 s

Full octave band results (untreated):

Broadband RT60 (avg 500, 1000 Hz) = (1.12 + 0.87) / 2 = 0.99 s

This room is a reverberant box. The 500 Hz band is particularly bad at 1.12 seconds — right in the speech frequency range. Every word spoken into the microphone arrives with 1.12 seconds of room tail. Any recording made in this room will sound hollow and echoey.

Scenario 2: Budget Treatment (6 m² of 50mm Mineral Wool Panels)

Adding six 1 m x 1 m x 50 mm mineral wool panels (rigid fibreglass or rock wool, density 48–64 kg/m³). Three on the rear wall behind the microphone, two on side walls at first reflection points, one on the ceiling above the recording position.

The treatment replaces 6 m² of painted plasterboard (alpha = 0.04–0.10 at most frequencies). The net absorption gain at 1000 Hz:

New absorption from panels: 6.0 x 0.90 = 5.40 Removed wall absorption: 6.0 x 0.04 = 0.24 Net gain: 5.40 - 0.24 = 5.16 m² Sabine

New total A(1000) = 4.87 + 5.16 = 10.03 m² Sabine

alpha_bar = 10.03 / 53.5 = 0.188

T60(1000 Hz) = 0.161 x 26.25 / 10.03 = 4.23 / 10.03 = 0.42 s

Full octave band results (6 m² treatment):

Broadband RT60 = (0.51 + 0.42) / 2 = 0.47 s

Significant improvement — the broadband RT60 dropped from 0.99 s to 0.47 s. But this is still above the 0.20–0.30 s target for a podcast room. And the 125 Hz RT60 is still 0.83 s — the bass is barely touched because 50mm panels do not absorb effectively below 250 Hz.

Scenario 3: Full Treatment (12 m² of 100mm Mineral Wool + Bass Traps)

Adding 8 m² of 100mm thick mineral wool panels on walls and ceiling, plus 4 m² of corner bass traps (100mm thick, mounted across room corners with an air gap).

(These replace 12 m² of original wall/ceiling surfaces.)

Total A(1000 Hz) = original untreated 4.87 + panels net (8.0 x 1.00 - 8.0 x 0.04) + traps net (4.0 x 0.85 - 4.0 x 0.08) = 4.87 + 7.68 + 3.08 = 15.63 m² Sabine

alpha_bar = 15.63 / 53.5 = 0.292

Using Eyring (alpha_bar > 0.20): -ln(1 - 0.292) = 0.346 T60(1000 Hz) = 0.161 x 26.25 / (53.5 x 0.346) = 4.23 / 18.49 = 0.23 s

Full octave band results (full treatment):

Broadband RT60 = (0.22 + 0.23) / 2 = 0.23 s

This is squarely in the podcast room target range (0.20–0.30 s). The bass traps brought the 125 Hz RT60 down from 0.83 s to 0.46 s — still higher than the mid-frequency values, but acceptable for speech recording. For critical music production, you might add additional corner traps to bring the 125 Hz RT60 below 0.35 s.

Treatment Summary

Cost estimates are for DIY installation using rigid mineral wool boards (Owens Corning 703, Rockwool RockBoard, or equivalent) at $15–$30/m² for material plus fabric wrap. Professional installation adds $20–$40/m² for labour.

Material Comparison: Foam vs Mineral Wool vs Fibreglass

The three most common treatment materials for home studios differ significantly in absorption performance, particularly at low frequencies. All NRC values below are per ASTM C423 test data.

Key insight: At 125 Hz, a 100mm mineral wool panel absorbs 2–3 times more sound than a 50mm acoustic foam panel. This is because low-frequency absorption is proportional to panel thickness (the quarter-wavelength rule). The wavelength at 125 Hz is 2.74 m, and a 50mm panel is only 1.8% of that wavelength — too thin to interact with the sound wave effectively. A 100mm panel, or a thinner panel mounted with an air gap, performs substantially better.

For home studios where bass control is the primary concern, mineral wool or fibreglass panels at 100mm thickness (or 50mm with a 50mm air gap behind) are the most cost-effective treatment. Acoustic foam is appropriate only when weight is a concern (e.g., mounting on a lightweight partition) or when low-frequency absorption is not critical (e.g., treating flutter echo between parallel walls at mid and high frequencies).

Placement Strategy: Where to Put Treatment

The calculator tells you how much treatment you need. Placement determines how effective that treatment is.

First reflection points. The most acoustically impactful positions are the first reflection points — the locations on walls, ceiling, and floor where sound from the source bounces once before reaching the microphone or listening position. Use the mirror method: sit at the recording/listening position, have someone slide a mirror along each wall surface. Wherever you can see the speaker or monitor in the mirror, that is a first reflection point. Place absorptive panels at these locations first.

Rear wall. The wall behind the listening position (in a control room) or behind the microphone (in a recording room) is the second priority. Reflections from the rear wall arrive with the longest delay (10–25 ms in a small room) and contribute most to the perceived "roominess" of the sound. Absorbing these late reflections reduces the comb filtering that degrades recording quality.

Corners. Room corners are where bass energy accumulates. Pressure-based absorbers (bass traps) placed in corners interact with the maximum pressure region of axial modes and are 2–4 times more effective per unit area than the same panels placed flat on a wall. Floor-to-ceiling corner traps in all four vertical corners can reduce the 125 Hz RT60 by 30–50%.

Ceiling. The ceiling reflection arrives at the microphone before any wall reflection (because the ceiling is typically the closest surface above the source). A cloud panel — a 1.2 m x 0.8 m absorptive panel suspended or mounted on the ceiling above the recording position — eliminates this reflection and significantly cleans up the recorded signal.

Common Home Studio Mistakes

Mistake 1: Covering every surface with foam. Over-treatment makes a room feel oppressively dead and fatiguing for extended sessions. The RT60 should not go below 0.15 seconds for speech recording or 0.20 seconds for music. The calculator shows you the point of diminishing returns — where adding more treatment reduces RT60 by less than 0.02 seconds per additional square metre.

Mistake 2: Thin foam on walls without bass treatment. Fifty millimetres of open-cell foam absorbs effectively at 1000 Hz and above but does almost nothing at 125 Hz. The result is a room that sounds muffled (because high-frequency reflections are absorbed) but boomy (because bass reflections persist). This frequency imbalance is worse than the untreated room because it introduces unnatural coloration.

Mistake 3: Egg cartons and mattresses. Egg cartons have an absorption coefficient of approximately 0.10–0.20 across all frequencies — barely better than painted plasterboard. Mattresses absorb mid and high frequencies but introduce resonance at their natural frequency and are a fire hazard. Neither is an effective acoustic treatment.

Mistake 4: Ignoring the floor. A hardwood or tile floor in a small room is a significant reflective surface. If the floor cannot be carpeted, a thick area rug (8–12 mm pile) at the recording position reduces floor reflections and contributes 0.20–0.35 absorption at mid frequencies.

Try the Free Studio Calculator

Enter your room dimensions and current surface materials. The calculator shows you the untreated RT60, how much absorption you need to reach your target, and exactly which frequency bands need attention. Compare treatment options — foam vs mineral wool vs fibreglass — and see the cost and performance tradeoff before you buy anything.

Open the studio RT60 calculator

Further Reading

• Free RT60 Calculator Online — No Signup, Instant ISO 3382 Results — the general-purpose calculator for any room type
• NRC 0.75 Does Not Mean 75% Absorption — Here Is What It Actually Means — why NRC alone is not enough
• How Acoustic Panels Actually Work: The Physics Explained — the science behind porous absorbers

References

• ISO 3382-2:2008 — Acoustics — Measurement of room acoustic parameters — Part 2: Reverberation time in ordinary rooms
• ISO 354:2003 — Acoustics — Measurement of sound absorption in a reverberation room
• ASTM C423 — Standard Test Method for Sound Absorption and Sound Absorption Coefficients by the Reverberation Room Method
• Toole, F. E. (2008). Sound Reproduction: The Acoustics and Psychoacoustics of Loudspeakers and Rooms. Focal Press.
• Everest, F. A. and Pohlmann, K. C. (2015). Master Handbook of Acoustics. 6th Edition. McGraw-Hill.
• EBU Tech 3276 (2004) — Listening Conditions for the Assessment of Sound Programme Material — Supplement 1: Studio Monitoring