Sauna vs Spa: What Is Actually the Difference?

Walk into almost any hotel and you will see the words "sauna and spa" printed together as if they are a single concept. Book a wellness break and the marketing copy will blur the two into something vaguely relaxing and expensive. But sauna and spa are distinct things — with different histories, different mechanisms, different health benefits, and very different price points.

Understanding the difference matters if you want to make the most of your wellness time and money.

What a Sauna Actually Is

A sauna is a heated room — typically between 70°C and 100°C — designed for dry heat bathing. The word comes from Finnish, and the practice is at least two thousand years old in that culture.

The defining feature of a sauna is its kiuas (stone stove), which heats the room and onto which you pour water to generate löyly — short bursts of steam that momentarily intensify the heat you feel on your skin. The humidity in a traditional Finnish sauna is low (typically 10–20%), which is what makes the very high temperatures tolerable.

A sauna session involves sitting in the heat, sweating heavily, then cooling down — in cold water, with fresh air, or in a cool room. This heat-cool cycle is repeated two to four times in a typical session.

What a Spa Actually Is

The word spa comes from the Belgian town of Spa, famous since Roman times for its mineral springs. In its original sense, a spa is a place where people come to bathe in and drink natural mineral waters believed to have healing properties.

In modern usage, the term has expanded enormously. Today, a "spa" can mean:

• A facility offering massage, facials, and beauty treatments
• A hotel wellness centre with a pool, steam room, and relaxation areas
• A thermal bathing complex built around natural hot springs
• An entire resort dedicated to health and wellness

The word has become so elastic that it means almost anything involving relaxation and some form of water or treatment.

The Key Differences

Heat source and type. A sauna uses dry heat from a wood or electric stove. A steam room (often called a spa by hotels) uses wet heat — 100% humidity at lower temperatures (around 40–50°C). Traditional spas built around mineral springs use naturally heated water.

Purpose and focus. Sauna is primarily about the physiological effects of heat and cooling: cardiovascular training, detoxification through sweat, immune stimulation, and deep relaxation. Spas typically focus more on beauty, pampering, and stress relief — with treatments performed on you rather than driven by your own physiological response to heat.