Choosing the right level of brightness is essential to set the mood in any room. It's therefore important to avoid spaces that are too dim, where you can't read or cook.
But you also need to be careful not to go overboard, avoiding a “dazzling” light when you want a relaxed and comfortable mood. In every situation, it’s therefore essential to choose the light bulb (or light bulbs) with the right number of lumens.
But what exactly are lumens? How many lumens are needed per square metre? And is there a direct correlation between watts and lumens? In this article, we’ll explore these questions and find out the ideal lumen solution for different rooms such as the bedroom and the kitchen.
What do we mean by lumen?
Lumens (lm) are the unit of measurement for the amount of light emitted by a light bulb or light source. In other words, lumens measure the total amount of visible light a light bulb emits. The higher the number of lumens, the brighter the light bulb.
And what about watt? The watt (w) is the unit of measurement for electrical power. It indicates the amount of electrical energy a device consumes or draws.
Is there a correspondence between watts and lumens?
Once, watts were used as a measure of a light bulb’s power because the relationship between light output and energy consumption was almost constant, but with the advent of LED technology, this relationship is no longer so direct. LED light bulbs use less energy than traditional incandescent light bulbs, but produce the same amount of light or even more, depending on their efficiency.
Therefore, there is no longer a fixed correlation between the number of watts and lumens. All light bulb packaging indicates the number of lumens emitted: comparing different light bulbs can help you estimate the desired brightness.
Photo @archifact_srl
If you are used to thinking in old watts, here are some rough conversion examples between lumens and watts for LED light bulbs, commonly available on the market today:
- A LED light bulb of 400–600 lumens (which today typically uses 4–5 watts) could be equivalent to a 40-watt incandescent light bulb.
- An 800-1000 lumen LED light bulb (which today typically uses 6-8 watts) could be equivalent to a 60-watt incandescent light bulb.
- A 1000-1200 lumen LED light bulb (which today typically uses 10-12 watts) could correspond to a 100 watt incandescent light bulb.
In general, it can be considered that, with current technology, to create 100 LED lumens you need about 1–2 watts.
The conversion between lumens and watts in LED light bulbs is, however, highly variable and depends not only on the energy class of the bulbs, but also on the colour of their glass. For example, with the same power (10W), the lumens produced by the Cone140 light bulb in its transparent version are 1100 lm, while in the smoky glass version they drop to 470 lm.
These figures make it quite clear how good LED lights are, not only in terms of brightness but also energy savings. LED solutions, in fact, allow you to save up to 90% compared to old incandescent light bulbs, and guarantee a lifespan that can be up to 15 times longer.
Photo @cockyhome
How many lumens per square metre?
The amount of light needed per square metre depends on the characteristics and use of the space. For example, a workspace such as an office or kitchen might require more intense light and generally a higher number of lumens compared to areas like a bedroom, where softer light will suffice. It’s also worth bearing in mind that dark walls tend to “absorb” more light, making a higher number of lumens necessary. In general, however, to achieve adequate lighting, an average of 200-400 lumens per square metre is recommended.
Light in the bedroom and light in the kitchen: is there a difference?
Yes, there is a difference in the recommended number of lumens for rooms with very different uses, such as the bedroom and the kitchen. Here is an average, bearing in mind that the numbers vary depending on the size, colours and furnishings of the room.
In the kitchen it’s essential to have good lighting for everyday activities like cooking and chopping ingredients. Excellent lighting and high colour rendering are crucial here. For this reason, we recommend a bright, intense light of around 1,000–3,000 lumens, with a higher concentration and directionality over the worktop and the dining area.
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The living room is a highly versatile space where we can do a range of activities, such as watching TV, entertaining friends, playing cards or reading. Finding the right lighting is therefore very important. A quantity of lumens starting from 600-800 is considered adequate, but the number can easily reach up to 3000 if the room is large. Ideally, you should combine different light sources, from the softest to the brightest, to suit every moment or area. So yes to a chandelier in the centre of the room, but also to multiple light points, cleverly created with wall lights or table lamps. And remember: a dimmer can really make a difference.
In the bedroom, the amount of lumens needed varies depending on several factors, including size, furnishings (in particular, whether or not there is a wardrobe), or the function of the room (for example, if the room is for children). Generally, however, lighting between 1000 and 2000 lumens can suit different needs. For bedside tables, on the other hand, a soft light is best—one that isn’t dazzling but is sufficient for reading: a light bulb of no less than 150 lumens is the ideal choice.
Taking a relaxing bath or a refreshing shower. Doing your makeup and shaving, but also brushing your teeth and hair removal. These are just some of the things we do in the bathroom, all different and for which specific lighting is essential. You can therefore consider lights with around 800 lumens above or beside the mirror to avoid shadows on your face. Then add a softer light with a lower brightness, around 300 lumens, to create the right atmosphere during moments of relaxation in the bath.
Transitional areas such as corridors or entrances, finally, require good visibility but not overly intense light: around 500-800 lumens will suffice.
And what are lux, exactly?
It is a unit of measurement used to quantify the lighting or luminous intensity perceived by an object or surface, that is, the luminous flux per square metre. One lux corresponds to the illumination produced by a candle placed one metre away and evenly distributed over a surface. In short, lux measures the amount of light that reaches a given area.
The higher the lux value, the more intense the perceived illumination.
