Sauna Capacity Planning for Gyms & Spas (Sizing Guide)

One of the most expensive mistakes gyms, spas, and wellness facilities make is undersizing—or oversizing—their sauna.

Capacity planning isn’t just about how many people fit inside a sauna. It directly impacts:

• Member satisfaction

• Heat consistency

• Energy efficiency

• Throughput during peak hours

• Equipment lifespan

• Revenue per square foot

This guide explains how to correctly plan sauna capacity for commercial environments, including:

• How many people a sauna should realistically serve

• Bench layout vs floor space

• Heater sizing for high-traffic use

• Peak-hour demand modeling

• Differences between gyms, spas, hotels, and recovery centers

If you’re designing or upgrading a commercial sauna, this article will help you size it correctly the first time.

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Why Capacity Planning Matters in Commercial Saunas

Residential sauna rules don’t scale well to commercial use.

In gyms and spas:

• Usage is continuous

• Doors open frequently

• Heat recovery matters

• Guests have different tolerance levels

• Waiting lines directly affect experience

A sauna that’s too small:

• Feels overcrowded

• Loses heat quickly

• Causes complaints

• Limits throughput

A sauna that’s too large:

• Costs more to install

• Uses more energy

• Takes longer to heat

• Sits underutilized off-peak

Capacity planning is about right-sizing, not maximizing.

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Sauna Capacity ≠ Square Footage Alone

Many people assume sauna capacity is based on floor area. That’s only part of the equation.

True capacity depends on:

• Bench length and depth

• Number of bench tiers

• Ceiling height

• Heater power and stone mass

• Door size and opening frequency

In commercial saunas, bench space matters more than floor space.

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The Real Rule: Bench Space Per Person

A realistic planning guideline:

Each sauna user needs 20–24 inches of bench length.

This allows:

• Comfortable sitting

• Safe posture

• Adequate spacing for heat circulation

Standing-room-only saunas are a red flag in commercial settings.

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Typical Commercial Sauna Capacities (Realistic Use)

These numbers assume continuous use, not occasional residential use.

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Bench Layout: The Hidden Capacity Multiplier

Multi-Level Benches Increase Throughput

Commercial saunas should almost always include:

• A full-length upper bench

• A secondary lower bench

Benefits:

• More seating

• Temperature choice

• Better airflow

• Reduced crowding perception

This is why traditional sauna layouts dominate commercial environments.

You can see examples of commercial-grade layouts with the Golden Designs Catalonia 8-person Infrared Sauna and the Golden Designs Toledo 6-Person Hybrid Indoor Sauna 

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Avoid Overcrowded U-Shapes

While U-shaped benches increase seating, they can:

• Trap heat unevenly

• Create dead airflow zones

• Make entry and exit difficult during peak times

For gyms, long straight benches often outperform complex layouts.

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Heater Sizing for Commercial Capacity

Residential Rules Don’t Apply

Commercial saunas need oversized heaters compared to residential spaces.

Why?

• Frequent door openings

• Higher turnover

• Shorter session times

• Continuous operation

Undersized heaters lead to:

• Long recovery times

• Inconsistent heat

• Increased element wear

Use commercial-rated heaters only, such as those in our Commercial Sauna Heaters collection.

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Stone Mass Matters

More users = more heat loss.

Commercial heaters should have:

• Large stone capacity

• High thermal mass

• Fast recovery capability

This keeps the sauna stable even during peak usage.

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Peak-Hour Demand Planning (The Most Overlooked Step)

Capacity should be based on peak usage, not average use.

Example: Gym Sauna Demand

• 1,200-member gym

• 5% using sauna during peak hour

• 60 members/hour potential demand

You don’t seat all 60—but you need enough capacity to:

• Rotate users

• Avoid long waits

• Maintain heat quality

This often means:

• Larger sauna

• Or multiple smaller saunas

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One Large Sauna vs Multiple Smaller Saunas

One Large Sauna

Pros

• Lower total equipment cost

• Easier maintenance

• Single control system

Cons

• Single point of failure

• Crowding during peak hours

• Harder to regulate experience

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Multiple Smaller Saunas

Pros

• Better flow control

• Redundancy

• Different temperature options

• Easier maintenance scheduling

Cons

• Higher upfront cost

• More space required

Many high-end gyms use two medium saunas instead of one large one.

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Infrared Saunas in Gyms & Spas: Capacity Considerations

Infrared saunas operate differently:

• Lower temperatures

• Individual seating focus

• Longer sessions

They work best as:

• Supplementary offerings

• Recovery-focused rooms

• Appointment-based amenities

Infrared saunas are not ideal replacements for high-throughput traditional saunas but pair well alongside them.

Explore options in our Infrared Saunas collection.

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Gender-Segregated vs Co-Ed Capacity Planning

If saunas are:

• Separate for men and women → plan capacity per room

• Co-ed → larger single room or dual rooms

Underestimating one side is a common mistake, especially in gyms with uneven usage patterns.

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Ventilation & Capacity Go Hand-in-Hand

More people = more:

• Oxygen demand

• Moisture load

• CO₂ buildup

Commercial saunas must have:

• Proper passive ventilation

• Or mechanical ventilation if required by code

Poor ventilation reduces usable capacity even if seating is available.

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ADA & Accessibility Impact on Capacity

Accessible design may require:

• Additional clear floor space

• Lower bench sections

• Wider doors

This can slightly reduce seating density—but increases usability and compliance.

For deeper guidance, see ADA Considerations for Commercial Saunas.

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Common Capacity Planning Mistakes

• Using residential sizing rules

• Ignoring peak-hour demand

• Underestimating door openings

• Choosing heaters with insufficient recovery

• Prioritizing aesthetics over bench space

• Not planning for future growth

These mistakes often require costly retrofits later.

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Capacity Planning Checklist for Gyms & Spas

Before finalizing your sauna:

• Estimate peak-hour usage

• Define target throughput

• Choose bench layout intentionally

• Oversize heater appropriately

• Plan ventilation early

• Confirm ADA considerations

• Leave room for future expansion

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Final Thoughts: Sauna Capacity Is a Business Decision

For gyms and spas, sauna capacity isn’t just design—it’s operations and revenue.

A properly sized sauna:

• Handles peak demand

• Maintains consistent heat

• Improves member satisfaction

• Reduces complaints

• Extends equipment life

If you’re planning a new commercial sauna or upgrading an existing one, Haven of Heat can help you model capacity, select commercial-grade heaters, and design layouts that work in the real world—not just on paper.