How many kW do you need to heat your space? Here’s how to calculate it easily

When you choose a Zibro laser heater or tube heater, one of the most important questions is: how many kW of power do I need? Too little power means your space won’t get warm enough. Too much means unnecessary costs and inefficiency.

In this article, we explain step by step how you can calculate this easily. No guesswork, but a practical method you can apply right away.

What does kW mean for a kerosene heater?

The power of a heater is expressed in kilowatts (kW). This indicates how much heat the heater can give off per hour. Simply put: the higher the kW, the larger the space you can heat.

At Zibro, you will find laser heaters and tube heaters with different power levels, so you can always choose the right model for your situation.

Step-by-step method to calculate kW

The basic formula we use is:

Required power (kW) = (room volume in m³) × (W/m³ factor)

Where:

• Room volume = length × width × height (in meters)
• W/m³ factor = heat demand per cubic meter

The W/m³ factor depends on:

• Insulation of the space
• Outside temperature
• How “airtight” the space is

Helpful guideline for the W/m³ factor

• Poorly insulated / unheated: 70–90 W/m³
• Moderately insulated: 50–70 W/m³
• Well insulated: 30–50 W/m³

Want to keep it simple?

Use 60 W/m³ as a guideline for a standard space.

Example calculation

Suppose you have a workshop of 8 m × 6 m × 2.5 m = 120 m³.

We take 60 W/m³ (standard):

120 m³ × 25 W/m³ = 3000 W = 3.0 kW

In this example, you need about 3.0 kW of power to comfortably warm the space.

How to choose the right Zibro heater?

Now that we know you need about 7.2 kW, look at the right category:

• Laser heaters with 6–8 kW – ideal for living spaces and well-insulated rooms
• Laser heaters with 8+ kW – for larger or hard-to-heat spaces
• Tube heaters around 7 kW – good solution without electricity, e.g. garage or workshop

If your power need falls between two sizes, generally choose the slightly larger model for more comfort and faster warming.

Practical tips for a more accurate result

• Also check the FAQ for ventilation and safety tips.
• Take into account:
• Quality of insulation
• Height of the space
• How often you use the heater
• When in doubt, a little extra kW can be more comfortable than too little.

Frequently asked questions about power

Can I use a laser heater in poorly insulated spaces?

Yes — but then calculate with a higher W/m³ factor (70–90 W/m³) to avoid underpowering.

How many kW is normal for a garage?

For an average garage (±15–30 m²), usually 5–8 kW is enough, depending on insulation and desired temperature.

Can a tube heater provide enough power?

Certainly — tube heaters around 6–8 kW are well suited for workshops and sheds, especially if you have no electricity.

Conclusion

You choose the right kW by calculating volume × heat demand. With our step-by-step method, you know exactly what you need, without guessing.

Use this to search specifically among the laser heaters and tube heaters on ZibroOnline. This way you avoid disappointments and ensure efficient, comfortable heating.