Summarize
- Lumen measures the amount of light produced by a light source
- Watt measures the energy consumed by a light source to produce light
- LED lamps are more energy efficient than traditional incandescent lamps
- Luminous efficacy is how efficiently electricity is converted into light
- Different rooms require different amounts of lumen for lighting
Lumen and Watti, how do they differ and what do they have in common?
Lumens are mainly used to determine the light intensity of a bulb. A larger lumen volume always indicates a larger amount of light.
A watt is again a unit of power consumed by a bulb to produce light. The higher the wattage of a lamp, the brighter the light it produces. A 12 W bulb burns much more brightly than a 6 W bulb.
What is Lumen?
The luminous flux, or lumen output, is an expression of the luminous efficacy of light.
It therefore indicates the luminous intensity of light. The higher the lumen value, the higher the lighting efficiency of the bulb, and vice versa. The exact figure is given by the manufacturer, as the specification is influenced by factors such as the shape of the lamp body, colour and other factors affecting light reflection.
The lumen is the best indicator of the overall light output of a luminaire.
Lumens (abbreviated as lm) therefore express the total visibility of light from any light source to the human eye.
Exactly how many lumens are needed to say that we are in a well-lit space? Such an accurate reading can be multiplied by the different uses of the premises. The number of lumens depends on several factors, such as the shape and size of the room, the height of the ceilings, the needs of the person and the type of light source (shade, direct, indirect).
According to various sources, the basic amounts are calculated to 1 m2 . In this respect, the size of the room is therefore a decisive factor. Different rooms in the home need different levels of lighting. For the kitchen, 400 – 500 lumens per square metre are needed, while for the bathroom (where make-up is applied) 600 – 800 lumens per square metre can be considered.
What is a watt?
People usually buy each light according to its wattage. But why? People are quite conscious of buying light bulbs after looking at the watts, as this has been easy when incandescent lamps were the only technology available. The higher wattage of the lamp indicated that it was brighter. Because in the days of incandescent light bulbs, everyone knew that the amount of light (and heat) was directly related to the watts.
A watt is a unit of power from which the energy consumption of a light source can be determined, in kWh.
The Led mixes up this equation dramatically. What we have learned in the past is no longer true in the same way. The wattage still describes the light output of a light source, and LED bulbs are now more efficient and do not use as much energy, thus reducing the size of the electricity bill. But the luminous efficacy per watt varies in LEDs.
Lumens versus watts
Lumens describe the brightness of light sources: the more lumens, the brighter the light produced by the lamp. The number of lumens varies according to the type of light source and the wattage indicates the power consumed by the lamp. If the brightness of a light source increases but the wattage does not, it indicates that more energy-efficient lumens and lower power consumption are being achieved.
Lumen and watt, their relationship
An incandescent lamp with a wattage of 100 W produces an average of 1 600 lumens. It can therefore be said that the output of 1 watt is 16 lumens. This is obtained by dividing 1 600 lumens by 100 W. For example, an LED lamp that produces 1 600 lumens of light may consume 14 W. 1 watt of such a lamp produces 114 lumens.
Lumens to watts conversion
Converting lumens to watts unequivocally is not really possible with LEDs, because LEDs have different luminous efficiencies per watt. A LED can produce 130 lm/w, for example, so if you want 1300 lumens, you need a 10 watt LED. Some LEDs designed for long life and high quality colour rendering index, the lm/w figure is lower, as in the example 114 above, but the quality is correspondingly higher. I have written about this in our article: a new energy label for LED lights.
Different lighting technologies and energy efficiency
The table illustrates the specific characteristics of each type of light bulb, including incandescent, halogen, CFL and LED. After looking at the table, you will quickly notice the things that distinguish each type from the others.
| ARVOT | HEHKULAMPPU | HALOGENEI | LOISTEPUTKI | LED |
|---|---|---|---|---|
| Consumption | 100 W | 70 W | 20 W | 12 W |
| Efficiency | 16 lm/W | 22 lm/W | 80 lm/W | 130 lm/W |
| Lifetime (hours) | 1 000 h | 2 500 h | 10 000 h | 50 000 h |
| Price | Cheap | Cheap | Medium price | Expensive |
| Running costs | Very expensive | Expensive | Mid-priced | Cheap |
Lumen and Watt, conversion
Lumen (lm) is the standard unit for luminous flux. It can be expressed as the amount of luminous flux from a light source incident on an area in a unit of time. In contrast, the Watt is a typical unit of time for electrical power. It is measured in joules per second (j /s).
Lumens / Watts = luminous efficacy
Explanation of luminous efficacy
Determining luminous efficacy is the ability of a luminaire to convert the electricity it consumes into light, or watts into lumens. The luminous efficacy of older technology lamps was very low, only 12 lm/W, but LED lights today are capable of over 200 lm/W at best. The LED has produced over 300 lm/W in the laboratory, but such a commercial product would be a very short-lived luminaire, as the hotter the operating temperature of the LED, the shorter its lifetime. You can read more about this in our article Led can’t take the heat.
In the case of LED lights, the characteristics of the luminaire (colour rendering index (CRI), lifetime, manufacturing method and materials) strongly influence the final lumen output. With current technology, a luminous efficacy of 135 lm/W at 85 – 95 colour rendering is good. By increasing the colour rendering to between 95 and 100, a good luminous efficiency is 100 lm/W. It is therefore quite clear that current technology offers significant energy saving advantages over incandescent lamps (16 lm/W), but efficiency must not take precedence over other quality factors.
Lumen and wattage recommendation for different rooms
There are many lumen recommendations around the world. In this case, we are talking about the characteristics of the luminaires. In lighting design, the concept of lux is used to define the desired level of light. The luminaire is chosen on the basis of the desired luxury levels, i.e. the amount of light in the room. I will briefly go through some guidelines here. For example, the Federation of the Visually Impaired recommends that attention should be paid to good general lighting for people with normal vision as well as those with impaired vision. Contrasts and glare in particular are the focus of attention. Power alone does not make a space good lighting-wise. For general educational, customer service, and office spaces, the 500 lux recommendation is good.
When choosing luminaires for different rooms in the home, it is important to consider both the luminous efficacy of the luminaire and its suitability to the shape of the room. In addition, the desired style and atmosphere are essential when choosing the light. From a purely cost point of view, the most efficient way of lighting is to use low and efficient lights, but other considerations should be taken into account in the design. Lighting recommendations based on our experience include the following:
Kitchen
The kitchen, and especially the worktops, are the corners of the house where bright light is essential. For workplace lighting, you should choose a LED light light, for example, which produces around 1 000 lumens/m. It therefore provides enough light for a light level of about 500 lux in a cantilevered aluminium profile. Naturally, the distance from the light source to the surface of the plane is one of the factors that will affect this. A more neutral shade of light is recommended to improve contrast.
Living room
The living room is a place where you want to relax enough, and there is room for children to play on the floor. The basic light output is 200 to 300 lux. For example, in a rectangular room with a surface area of 20 m2 and a room height of 2.5 m, this is obtained by selecting 6 Plafondi 200 luminaires with a lumen output per luminaire of 1 300. The light is directed directly downwards from the luminaire, i.e. it is a light luminaire with an opening angle of 110 degrees, i.e. wide. The input power of one lamp is 15 W, so with this type of lamp the total power would be 90 W. So roughly speaking, 100 W of LED power is enough to light a 20 m2 living room. This is also obtained, for example, with 6 pcs of 9 W spotlights (e.g. Round 033) with a lumen output light of about 600.
Dining room
The dinner table is a quiet place for the family to relax, and often a warmer light light is all that’s needed, providing 300-400 litres of light on the table. Nowadays, of course, the situation has changed because people work remotely in their homes a lot. Then a variable amount of light is in place.
Bedroom
The bedroom is a place of relaxation, with a soft feeling of light and a warm tone. For an adult bedroom, the lighting efficiency is around 200 – 300 lux. In a child’s room, on the other hand, you can have a lot more light for playing and doing homework, around 400-500 lux.
Office
In the workplace, people need brighter light to concentrate fully on their work. The working space should be 800 -1 000 lux.
Bathroom
Bathrooms are where some people want a spa atmosphere. in which case 120 – 200 luchs is good enough. While others just want to do their make-up quickly, and a bright 500 lux of light is not too much. Different light sources should be used in the bathroom as needed, achieving light levels of 100-800 lux. The light intensity can therefore be adjusted as needed.
Discover the technical features
Energy labelling
Before buying LED lights, it is better to check the energy labels. The energy label illustrates the maximum amount of energy a light bulb can consume and is shown on your electricity bill. The energy labels also provide information on the life of the lamp. The new regulations changed the energy labelling of LEDs. I wrote about this in a blog article on a New energy label for LED lights.
Colour rendering index
The colour rendering index (CRI) is another factor that applies to any light source. It tells you how the colours appear in the light of that particular LED. The index is usually between 0 and 100. If colour rendering is not mentioned, it always raises more questions and so I would not buy such a lamp.
A CRI of 85 or more is considered acceptable. Whereas CRI 95 is already excellent and reproduces all colours naturally.
Colour temperature
Colour temperature is the “colour” of white light emitted by a light source, expressed in Kelvin. The colour temperature is usually between 2 000 and 6 500 K. In luminaires, warm white is around 2800 Kelvin, tending towards yellowish or orange. The 4 000 Kelvin scale is a neutral colour temperature, where the shade of light is neither warm nor cold. The cold shade of the luminaires, on the other hand, is around 5 500 Kelvin. The standard daylight for lighting and video set-ups, for example, is typically 6 500 Kelvin, but in living spaces it is quite unnatural for most of the year and most of the day.
Other technical reading
Led lights and price- What does Led lighting cost?
CRI and RA – What is the difference between CRI and RA?
Make your face beautiful – What is good make-up lighting?
Led lighting expert
LedStore has been an expert in LED lighting and lighting design since 2010. We have our own product design, so our products are technologically state-of-the-art. Products have quarantee for up to 7 years. We also carry out lighting maintenance.
We focus on temperature-controlled and high colour rendering lights, so they work brilliantly and last a long time. We do around 500 lighting designs for our clients’ sites. Read more here or order a lighting design
We offer a service of custom-made led strips, i.e. custom-made led strips in aluminium profile. Also installed. Did you know?
LedStore offers lighting design from 169 euros for the whole house!
Remember that we are always ready to offer our help to you along the way, by email (myynti@ledstore.fi) and by phone (045 251 4510). As always, feel free to share photos of your own projects on social media at ledstore.fi at Instagram and ledstore.fi at Meta. We love to see the cool things done by our LEDs, and it also helps to provide inspiration for those who are not sure about the power and awesomeness of LEDs. Did you know that we already have over 3500 pictures of our LED installations in our Gallery!
Photo gallery of Led lights:
Product gallery: Pictures of products in different installation locations
Indirect light: Indirect light in different spaces
Room-specific: Light in different rooms
References: Complete houses that have been photographed
FAQ
1. What is the difference between lumen and watts?
A lumen (lm) measures the amount of light produced by a light source, or luminous flux, while a watt (W) measures energy consumption, or electrical power. Traditionally, higher wattage meant brighter light, but with LED technology this relationship is no longer so straightforward.
2. Why are lumens more important than watts when choosing lighting?
Lumens give a direct indication of the amount of light produced by a light source, which helps to assess the brightness of the lighting. Wattage, on the other hand, indicates energy consumption, but not necessarily lighting efficiency, especially between different types of light sources.
3. How many lumens are needed in different rooms?
The amount of lumen required depends on the use of the room:
- Kitchen: 400-500 lm/m²
- Bathroom: 600-800 lm/m²
Also consider the size, shape and surface materials of the room when planning lighting.
4. How does the energy efficiency of LED lights compare to traditional light bulbs?
LED lights are significantly more energy efficient than incandescent bulbs. For example, a 100 W incandescent bulb produces around 1 600 lumens, while an LED with the same amount of light consumes only around 14 W, which means energy savings of more than 80%.
5. Why does the wattage no longer tell you how bright the light is?
The energy efficiency of different light sources, such as incandescent and LED lights, varies greatly. The same wattage can produce different amounts of light depending on the lighting technology, so the wattage alone is no longer an indication of the brightness of the light.
6. Are lumen and wattage related?
There is no direct relationship between lumens and watts in LEDs. The lumen indicates the amount of luminous flux, and the watt indicates the energy consumption. Both values are important values for luminaires and bulbs to determine luminous efficacy.
7. How many lumens are in 1 watt?
A standard 60 W incandescent bulb can produce a luminous flux of around 750 lumens. Thus, we can say that 1 watt = 12.5 lumens. This number of lumens is obtained by dividing 750 lumens by 60 watts. If we consider a 6 watt LED with a light output of 500 lumens, then 1 watt will give 83.3 lumens.
8. Is 800 lumens too much?
First you need to know what that 800 lumens will be used for. In a dining room, a single lamp with a light output of 800 lumens can be considered good, as people appreciate good light when working remotely. But in the bedroom, the same amount of light is already too much if it is evenly distributed throughout the room. It must be remembered that the lumens in one lamp are spread out into the environment and the final number of lumens depends on the need and the square footage of the space to be illuminated.
9. How large an area does 1 000 lumens illuminate?
1 000 lumens with an omnidirectional light source illuminates a 2 to 3 metre area around the luminaire to a basic illumination level. 1,000 lumens will give you the light you need for a worktop, for example, but it’s still too much for a quiet meal. An outdoor lamp producing 1 000 lumens of light can be seen over 100 metres away.
10. Are different amounts of lumen necessary in different rooms?
Every room in the house is different. And the need for light varies according to the use of space. Rather put too much light and a dimmer, than too little light.
