How to choose the suitable beam angle of underwater lights?

Water Feature pool

What is beam angle?

The center of the light source is usually the brightest. Establish a reference line from the position with the brightest light source intensity and then select an area of 50% light intensity from either side of the reference line. Therefore the angle they form is the beam angle.

light beam angle

Or for example, suppose all lights are like a flashlight, and the brighter part of the flashlight’s beam is the beam angle.

light beam angle

Why do you need to choose the right beam angle?

If the beam angle of the underwater light is not set correctly, then the illuminated area will appear too bright, too dark or the light effect will be confusing. Some inappropriate beam angles can even cause glare, which can be harmful to your health.

Choosing the right beam angle will give you the best lighting effect. After that, create a better lighting atmosphere for the part or whole. Your pool, fountain or water feature will be much more pleasing to the eyes.

The beam angle of the underwater lights


Common beam angles for pool lights are 15°, 30°, 45°, 60° and 120°, and for underwater spotlights and fountain lights are 15°, 30°, 45° and 60°. The lighting area for these beam angles is conical.


Some pool lights use special designs in structures such as lenses. Therefore, there are some special beam angles. For instance, 15X50° and 15X60°. This light illuminates the area at a narrower angle in two directions. The illuminated area of these beam angles looks like a squashed cone.

How to choose?

Factors influencing the choice of beam angle

The narrower the beam angle of the underwater light source, the smaller the illuminated area and the greater the illumination distance.

The narrow beam angle has a small illuminated area, a prominent centre and a strong visual effect, making it suitable for accent lighting. If you need to illuminate an important area or create eye-catching lighting, choose a narrower one.

The wider the beam angle of the underwater light source, the larger the area illuminated and the shorter the distance illuminated. A wide beam angle can illuminate a large area. It also creates a more even lighting effect as the light is more spread out.

The choice of beam angle is not fixed, the following factors will influence the choice :

  • Application scenario
  • Ambient light
  • Pool shape and size
  • Type of light
  • Number and distribution of luminaires
  • Light wattage
  • Lighting efficiency requirements

Take the application scenario of pool step lights as an example :

If the steps are narrow and you wish to have an aesthetically pleasing decorative effect, you can install a pool light with a narrow beam angle (e.g. 30°) on the pool wall on the same side of each step.

If you do not want to install too many step lights, you can also choose to install only one pool light with a wide beam angle (e.g. 120°) on the side wall near the centre. This type of installation will significantly reduce purchase, installation and maintenance costs.

lighting pool  steps

Read Pool Step Lighting: A Detailed Guide to Learn More.

How to solve?

A knowledgeable user or pool constructor will tell WAKING what lighting effect it wants to achieve directly and ask the vendor to provide a product test report when purchasing.

WAKING provide light angle parameters and reference diagrams in product parameters and details to help you understand the characteristics of the luminaires and make the choice.

If you’re not sure what to choose, contact WAKING. Our professional sales staff and engineers will look at your pool design and help you make the most appropriate choice based on your lighting requirements.

A WAKING customer in Qatar wanted to light his two landscaped swimming pools. On WAKING’s advice, the customer chose the 15° pool luminaire. After installation, the lighting was perfect and the customer was very satisfied.

How to measure?

When the underwater light is installed, experienced people can roughly estimate the beam angle of the light if the illuminated area contrasts well with the surroundings.

In lighting, precise measurements can be made using distributed photometry. In addition to measuring the beam angle, a distributed photometer can also measure the light intensity distribution curve, total luminous flux, brightness distribution, glare level and other data.

Below are measurements for the two most common LED chips :

COB chip 45° lens

COB LED chip beam angle

Illuminated area at different throw distances and average brightness within the area

COB LED chip beam angle

Light distribution diagram for indoor use

SMD 120° no lens

SMD LED chip beam angle

Illuminated area at different throw distances and average brightness within the area

SMD LED chip beam angle

Light distribution diagram for indoor use

Are you looking for a professional underwater light supplier? Contact us now!

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