Selecting the wrong RT60 target is one of the most common — and most expensive — mistakes in acoustic design. A consultant specifying a concert hall target for a classroom ends up with a room where no child can understand speech. An architect using an office target for a lecture theatre produces a dead, uncomfortable space. The wrong number, applied to the right calculation, still produces the wrong outcome.
This reference card gives you the correct RT60 targets for more than 20 room types across the five standards most widely referenced in commercial acoustic design practice. The values are taken directly from the published standards — not simplified or approximated. Use this card to set targets at the start of every project and to verify compliance at the end.
To calculate whether a specific room will meet these targets, use the RT60 Quick Calculator.
What This Reference Card Is
This is a consolidated lookup table. It exists because the standards themselves are not cross-referenced — ISO 3382 does not mention BB93, DIN 18041 does not cite ANSI S12.60, and WELL v2 sits in a completely separate certification framework. If you are designing a room that must satisfy multiple frameworks simultaneously (a school in a WELL-registered building, for example), you need to know all the applicable targets and identify the most restrictive one.
The card is structured as a table with six columns: room type, typical volume range, standard, RT60 target (mid-frequency), tolerance, and the specific clause in the standard. Where a standard provides a volume-dependent formula, the table shows calculated values at representative volumes.
Who Needs This Reference
Acoustic consultants — as a quick sanity check when switching between project types. It is easy to carry the mental model of one building type into a project of a different type.
Architects — when writing a project brief or checking whether a proposed room volume will make the acoustic target achievable without excessive treatment.
Facilities managers — when commissioning post-occupancy measurements and needing to know what pass/fail threshold to apply to results.
Building certification assessors — particularly WELL APs and BREEAM assessors who need to confirm the correct Part of Feature 74 applies to a given space configuration.
Contractors and fit-out teams — when reviewing acoustic specifications on tender documents and assessing whether the stated targets are consistent with the standards cited.
The Complete RT60 Target Table
All RT60 values are mid-frequency averages (500 Hz and 1000 Hz average) unless noted. "Mid-freq" = average of 500 Hz and 1000 Hz octave bands. Volume ranges are typical for the room type — consult the standard for precise volume-dependent formulae.
Education
| Room Type | Volume Range | Standard | RT60 Target | Tolerance | Clause |
|---|---|---|---|---|---|
| Primary classroom | 100–200 m³ | BB93:2015 | 0.4–0.6 s | ±0.1 s | Table 1 |
| Primary classroom | ≤ 283 m³ | ANSI S12.60-2010 | ≤ 0.6 s | — | §5.3 |
| Secondary classroom | 150–300 m³ | BB93:2015 | 0.4–0.8 s | ±0.1 s | Table 1 |
| Lecture theatre | 300–2000 m³ | DIN 18041:2016 | 0.6–1.0 s | ±20% | §3.3 Group A3 |
| Music teaching room | 100–300 m³ | BB93:2015 | 0.6–1.0 s | ±0.1 s | Table 3 |
| Library (quiet study) | 200–800 m³ | DIN 18041:2016 | 0.5–0.7 s | ±0.1 s | Group B |
| Sports hall | 1000–5000 m³ | BB93:2015 | ≤ 1.5 s | — | §3.5 |
| School dining hall | 500–2000 m³ | BB93:2015 | ≤ 1.0 s | — | §3.5 |
Offices and Commercial
| Room Type | Volume Range | Standard | RT60 Target | Tolerance | Clause |
|---|---|---|---|---|---|
| Meeting room (≤12 persons) | 50–150 m³ | WELL v2 Feature 74 | ≤ 0.5 s | — | Part L07 |
| Open-plan office | 500–3000 m³ | WELL v2 Feature 74 | ≤ 0.6 s | — | Part L07 |
| Open-plan office | 200–2000 m³ | DIN 18041:2016 Group B | 0.6 × V^(1/3) s ± 20% | ±20% | §3.4 |
| Private office | 20–50 m³ | DIN 18041:2016 Group B | 0.4–0.6 s | ±0.1 s | §3.4 |
| Call centre | 300–2000 m³ | ISO 3382-3:2012 | ≤ 0.6 s | — | Informative |
| Reception / lobby | 200–1500 m³ | DIN 18041:2016 Group B | 0.6–1.0 s | ±20% | §3.4 |
Healthcare
| Room Type | Volume Range | Standard | RT60 Target | Tolerance | Clause |
|---|---|---|---|---|---|
| Patient ward | 200–600 m³ | HTM 08-01:2013 | ≤ 0.8 s | — | §5.4 |
| Consulting room | 20–60 m³ | ISO 3382-2:2008 | 0.3–0.5 s | ±0.1 s | Informative |
| Hospital corridor | 100–500 m³ | HTM 08-01:2013 | ≤ 1.0 s | — | §5.5 |
| Rehabilitation gym | 300–1000 m³ | HTM 08-01:2013 | ≤ 1.5 s | — | §5.6 |
Performance and Worship
| Room Type | Volume Range | Standard | RT60 Target | Tolerance | Clause |
|---|---|---|---|---|---|
| Concert hall (orchestral) | 5000–25000 m³ | ISO 3382-1:2009 | 1.8–2.2 s | ±0.2 s | §A.1 |
| Opera house | 3000–10000 m³ | ISO 3382-1:2009 | 1.3–1.6 s | ±0.2 s | §A.1 |
| Drama theatre | 1000–5000 m³ | ISO 3382-1:2009 | 0.8–1.2 s | ±0.1 s | §A.1 |
| Multi-purpose hall | 1000–8000 m³ | DIN 18041:2016 Group A1 | 1.4–1.8 s | ±20% | §3.2 |
| Church (speech-focused) | 500–3000 m³ | DIN 18041:2016 Group A3 | 0.8–1.2 s | ±20% | §3.3 |
| Cathedral | 5000–50000 m³ | ISO 3382-1:2009 | 2.5–6.0 s | — | Informative |
| Recording studio (live room) | 50–300 m³ | AES-recommended | 0.2–0.5 s | ±0.05 s | — |
| Recording studio (control room) | 30–80 m³ | AES-recommended | 0.2–0.35 s | ±0.05 s | — |
| Home cinema | 30–150 m³ | Dolby/THX | 0.2–0.4 s | ±0.05 s | — |
Hospitality and Retail
| Room Type | Volume Range | Standard | RT60 Target | Tolerance | Clause |
|---|---|---|---|---|---|
| Restaurant (casual dining) | 200–800 m³ | DIN 18041:2016 Group B | 0.8–1.2 s | ±20% | §3.4 |
| Hotel meeting room | 50–300 m³ | WELL v2 Feature 74 | ≤ 0.5 s | — | Part L07 |
| Hotel lobby | 300–2000 m³ | ISO 3382-2:2008 | 0.8–1.4 s | — | Informative |
How to Use This Table
Step 1: Identify the room type. Be precise. A room described as "multi-purpose" may need to meet two different standards simultaneously — check whether it will primarily host speech events or music events.
Step 2: Confirm which standards apply. A school project in England must meet BB93. If the school also pursues WELL certification, Feature 74 Part L07 applies on top. Where two standards conflict, apply the more restrictive target.
Step 3: Check the volume dependency. DIN 18041 is particularly important here. The standard specifies RT60 as a function of room volume using the formula T_soll = 0.45 × V^(1/3) for Group A2 spaces (general assembly rooms). At 200 m³ this gives 0.45 × 5.85 = 2.6 s as a baseline, then scaled to the appropriate usage group multiplier. Calculate, don't estimate.
Step 4: Apply the tolerance. Standards define both a target and a tolerance. A classroom with measured RT60 of 0.62 s against a target of 0.6 s ± 0.1 s passes. A classroom at 0.72 s fails. The tolerance is not a buffer — it accounts for measurement uncertainty, not design margin.
Step 5: Check octave-band shape, not just mid-frequency average. The mid-frequency average is the primary compliance criterion for most standards, but low-frequency reverberation (125 Hz, 250 Hz) is typically longer than the average and can cause distinct problems — muddy speech, booming music, masking of low-frequency speech cues — even when the mid-frequency target is met. BB93 sets specific upper limits at 125 Hz.
Step 6: Run the calculation. Use the RT60 Quick Calculator to model whether your room surfaces will achieve the target, or use the full room builder at /calc for detailed octave-band analysis.
Standards Referenced
ISO 3382-1:2009 — Measurement of room acoustic parameters. Part 1: Performance spaces. Covers concert halls, opera houses, theatres, and auditoria. Defines EDT, T20, T30, T60, C80, D50, G, and spatial parameters. Annex A provides descriptive recommendations for performance spaces.
ISO 3382-2:2008 — Measurement of room acoustic parameters. Part 2: Reverberation time in ordinary rooms. Covers classrooms, offices, auditoria, and other non-performance spaces. Uses mid-frequency T20 or T30 as the primary metric.
ISO 3382-3:2012 — Open plan offices. Defines spatial decay of sound pressure level (D2,S), distraction distance (rD), and privacy radius (rP). Does not set hard RT60 targets for open offices but provides measurement context for WELL assessments.
DIN 18041:2016 — Acoustic quality in rooms. Germany's primary room acoustics standard, applicable across all major building types. Divides spaces into Group A (performance and assembly) and Group B (communication spaces). Provides volume-dependent target formula and usage-group multipliers.
BB93:2015 — Acoustic design of schools. UK Department for Education standard. Mandatory for state-funded schools in England. Sets RT60 limits for all major school space types, background noise limits (NR25 for classrooms), and sound insulation requirements.
ANSI S12.60-2010 / 2015 — Acoustical performance criteria, design requirements and guidelines for schools. US standard. Covers classrooms up to 283 m³. RT60 ≤ 0.6 s is the headline requirement; background noise limit is 35 dBA.
WELL v2 Feature 74 — Sound part of the WELL Building Standard. Seven parts (L01–L07) covering sound mapping, massing and layout, landing zones, exterior noise, mechanical noise, plumbing noise, and reverberation (L07). Targets RT60 ≤ 0.5 s for meeting rooms and ≤ 0.6 s for open areas.
How to Calculate Whether Your Room Will Hit the Target
The RT60 target tells you what you need to achieve. To know whether a specific room — with specific dimensions and surface materials — will actually reach that target, you need to calculate.
The Sabine formula gives a first approximation: T60 = 0.161 × V / A, where V is room volume in m³ and A is total absorption in m² sabins. If the target is 0.6 s and your 200 m³ room needs A = 0.161 × 200 / 0.6 = 53.7 m² of absorption, you can back-calculate how much acoustic treatment is needed.
Use the RT60 Quick Calculator to work through this in under two minutes, or the full simulator at /calc for detailed surface-by-surface analysis with octave-band breakdown.
For detailed methodology on choosing between Sabine and Eyring calculations, see RT60 Calculation: When Sabine Gets It Wrong.
For a deep dive into DIN 18041's volume-dependent formula, see the DIN 18041 Complete Guide.