One of the most common questions when designing pool lighting is how many LED spotlights should be installed. As a general guide, people usually refer to one spotlight for every 20 m² of water surface area, but this rule does not allow for the correct sizing of all installations.
The final figure depends on the projector’s luminous flux, the shape of the pool, the colour of the lining, the depth, the arrangement of the light fixtures and the desired effect. A light-coloured, rectangular pool does not have the same requirements as a dark-coloured pool, an L-shaped pool or a pool with steps and shallow areas.
How do you work out the surface area of a swimming pool?
The initial calculation should be based on the surface area of the water, not on the total volume of the tank.
In a rectangular swimming pool:
Pool area = length × width
For example, a swimming pool 8 metres long and 4 metres wide has:
8 × 4 = 32 m² in area
If we take one spotlight per 20 m² as a starting point:
32 ÷ 20 = 1.6
As it is not possible to install fractions of a projector, the initial estimate would be two LED spotlights.
This figure should be regarded as a starting point. Before finalising the installation, you must check which type of spotlight will be used and how the light will be distributed.
Guidance table based on pool size
The following table is based on an initial recommendation of one spotlight for every 20 m² for rectangular, light-coloured swimming pools with no special areas. The figure should be rounded up.
| Pool dimensions | Surface | Initial estimate |
|---|---|---|
| 4 × 3 m | 12 m² | 1 light bulb |
| 6 × 3 m | 18 m² | 1 light bulb |
| 7 × 3.5 m | 24.5 m² | 2 spotlights |
| 8 × 4 m | 32 m² | 2 spotlights |
| 10 × 5 m | 50 m² | 3 spotlights |
| 12 × 6 m | 72 m² | 4 spotlights |
These figures are not a substitute for a proper lighting design study. A 6 × 3-metre swimming pool might fall within the range of a single spotlight, but two well-spaced light sources may be more suitable when greater uniformity is required, RGB lighting is used, or there are elements that cast shadows.
Factors that may increase the number of outbreaks
Projector power and luminous flux
Not all LED spotlights provide the same level of illumination. The TRYLED range includes main spotlights with 2,000 or 4,100 lumens, whilst the mini models can provide 600 or 800 lumens. For this reason, the same number of units cannot be used for all of them.
Spotlights with a higher luminous flux can be used as the main lighting for the pool. Mini spotlights are particularly suitable for providing supplementary lighting for steps, benches, spas, pool decks or decorative areas.
Colour of the cladding
Pools with white or light-coloured linings make better use of light than dark pools. In black, dark grey or stainless steel pools, it may be necessary to increase the number of spotlights or use models with a higher light output.
The choice should not be based solely on the colour visible above the water. It is also important to consider how the finish behaves once the glass is full.
White light or RGB
The colours produced by an RGB system do not always create the same visual impression as white light. For this reason, manufacturers’ documentation recommends increasing the number of projectors when using certain RGB systems.
When the lighting is intended primarily to create atmospheric lighting effects, it is advisable to use several light sources rather than relying on a single central spotlight.
Shape of the swimming pool
Rectangular swimming pools are easier to light because it is simpler to plan the direction of the light beams.
In L-shaped, kidney-shaped, curved, indented or partitioned swimming pools, it is advisable to divide the pool into different areas. Each area must receive sufficient direct light to prevent a wall, a corner or a change in direction from casting a shadow over any part of it.
Stairs, benches and beaches
A Roman staircase, a hot tub area, a submerged beach or a bench may all require their own light source.
It is not always practical to install another main spotlight in these areas. Mini spotlights allow you to provide additional lighting for specific areas in a more discreet manner. TRYLED’s mini models are specifically designed for steps, benches, spas and shallow areas.
Desired result
Ambient lighting does not require the same number of spotlights as an installation where you want to see the entire bottom of the glass clearly.
Before carrying out the sizing exercise, three aspects must be defined:
- Whether the lighting will be mainly functional or decorative.
- Whether white, warm or RGB light will be used.
- Whether you’re looking for soft light or bright, even lighting.
Practical examples
6 × 3-metre swimming pool
It has a surface area of 18 m². The starting point would be a main spotlight.
However, two points may be recommended when:
- RGB is used.
- The cladding is dark.
- The aim is to avoid shadows.
- There is a staircase or a separate area.
- The chosen model has a low luminous flux.
8 × 4-metre swimming pool
It has a surface area of 32 m². The initial estimate would be two light fittings.
The spotlights should be positioned so that their beams cover the pool without leaving any dark areas. If there is a wide staircase, a beach or a bench, an additional mini spotlight can be fitted for that area.
10 × 5-metre swimming pool
It has a surface area of 50 m². The initial estimate would be three spotlights.
At this scale, it is particularly important to consider the spacing between the light sources. Installing a single, very powerful spotlight can result in an excessively bright area near the light source and reduced uniformity at the edges.
Irregular or L-shaped swimming pool
It is not advisable simply to calculate the total area and distribute the light fittings mathematically. Each wing or area should be considered as a separate space to prevent the walls from obstructing the spread of light.
Is it better to have one powerful spotlight or several spotlights spread out?
Total luminous flux is important, but so is its distribution.
Two or three projectors positioned correctly can produce a more even result than a single high-powered spotlight. Furthermore, they help to reduce the shadows cast by swimmers, steps, benches or changes in the shape of the pool.
The decision should be made by comparing:
- Lumens per projector.
- Angle of aperture.
- The distance to be covered.
- Number of walls and obstacles.
- Desired uniformity.
- The usual vantage point from which to view the swimming pool.
Where to position the LED spotlights around the swimming pool
As a general guideline, certain manufacturers recommend installing their spotlights between 40 and 70 centimetres below the surface. The exact measurement should be checked in the manual for each light fitting.
It is also advisable to:
- Point the spotlights away from the house or your usual observation point.
- Ensure that they are not directed straight towards terraces or seating areas.
- Spread them out to minimise the contrast between light and dark areas.
- Check that stairs and changes in level are clearly visible.
- Follow the manufacturer’s installation instructions.
- Size the transformer and the wiring for the entire set of luminaires.
Which type of spotlight to choose
For the main lighting, ultra-slim spotlights or PAR56 lamps can be used, depending on the type of swimming pool and whether it is a new installation or a replacement.
TRYLED PAR56 lamps are available in different light versions and in models offering 2,000 or 4,100 lumens. The ultra-slim spotlights allow for surface-mounted installations compatible with different types of glass.
Mini projectors can be reserved for:
- Stairs.
- Banks.
- Spas.
- Submerged beaches.
- Small swimming pools.
- Decorative touches.
Conclusion
The guideline of one light fitting per 20 m² is useful for making an initial estimate, but should not be applied automatically.
To work out how many LED spotlights a swimming pool needs, you need to consider the surface area, the shape of the pool, the lining, the type of light, the luminous flux and the layout of the spotlights.
In a professional installation, the aim is not to fit as many spotlights as possible, but to achieve balanced lighting, avoid dark areas and select products that are compatible with the fixture, the electrical system and the intended control system.
A swimming pool measuring 8 × 4 metres has a surface area of 32 m². Using one spotlight per 20 m² as a starting point, you would need two spotlights. This number may need to be increased if the pool is dark, if RGB lighting is used, or if there are steps and separate areas.
In terms of surface area, a single light fitting can be used as an initial estimate, as the swimming pool measures 18 m². However, two light fittings may be more suitable when aiming for even lighting or when using spotlights with a lower luminous flux.
Usually, yes. Manufacturers recommend using brighter lighting for swimming pools with dark finishes or stainless steel, although there is no universal percentage that applies to all products.
Some manufacturers recommend positioning them approximately 40 to 70 centimetres below the surface. You should always follow the instructions in the manual for the model you have installed.
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