How to Compare Light Fittings (Six Things to Check on a Spec Sheet)
Every manufacturer formats their data differently, and not all of it is as true as we would hope (some of it is very glamorous marketing dressed up as fact).
So, how do you compare two light fittings when the spec sheets won't play fair?
These are the six things I check first whether I'm choosing fittings for a client's kitchen or sizing up an alternative that's been submitted to me.
My advice can be used as a guide for residential lighting design. Working with a professional lighting designer is always recommended but knowing how to evaluate light fittings is valuable for everyone.
SIX key measurements of light quality:
LUMEN OUTPUT – (LM)
BEAM ANGLES AND FIELDS (°)
COLOUR RENDERING INDEX (CRI)
COLOUR TEMPERATURE - (CCT)
WATTS – (W)
GLARE – (UGR AND VISUAL TESTING)
With these six measurements, you can quickly gain an understanding of a light's performance. That lets you easily evaluate whether it's a reasonable alternative to another known light fitting.
Ultimately, nothing beats seeing a working sample, and testing your sample in a dark room will let you know if you're getting the light you want or not. If you're in Melbourne, our free Open Studio events are a great chance to see the difference for yourself. We only open our doors a few times a year and usually book out in a couple of days, so following our Eventbrite page is the only way to be the first to know.
1. Lumens: the only honest answer to "will it be bright enough?"
In simplest terms, lumens measure how much light is coming out of the light fitting. That's it!
If you need 150lm, then 800lm is not an alternative, regardless of the fact that you can dim the light.
Alternatives and off-spec'ing are a fact of light (and life). On any project, there will be people looking for ways to save money (or sell a preferred supplier's products), and the special "finesse" lights in a design are often the first to go. If the swaps are not made with consideration of the intent, they will never create the light you are expecting from your design. If you hate the result, changing your lighting once the ceilings are finished can cost far more than the swap ever saved.
Protecting the design intent when alternatives come in is a big part of what we do at MINT. We know that budgets are finite, and we know how to save you money by making the right compromises, in conversation with you, so you get the home of your dreams, not a nightmare.
It's also important to know that 500 diffuse lumens are NOT the same as 500 directional lumens:
Diffuse lumens spread in all directions and come "softly" out of a light fitting.
Directional lumens are aimed in a direction, so they travel further that way and create a more noticeable light effect.
The connection between beam angles, lumens and light directionality is important for keeping the finesse in your lighting design. Replacing a directional light with a "soft" light (or vice versa) is most definitely not going to create the same effect.
The most common question we hear is, "Are you sure it will be bright enough?"
The quantity of lumens you need for a room is determined by:
the light levels you are trying to achieve
the colours and reflectivity of the space
directionality
mood and function
As a starter:
A small highlight may only need 150 to 200 lumens.
Functional general light will likely need 600 to 800 lumens.
Indirect light for a bright room might need 3000 lumens or more from the indirect fitting; to compensate for the light lost as it reflects off the ceiling.
If you'd like a starting point for your own rooms, try our Lumen Calculator.
A great design will use a combination of types and strengths of light at different heights to create layers and balance in a room.
2. Beam Angles: why the widest beam is usually the glariest
Simply, the beam angle tells you what "size" the beam of light is, which describes how broad or narrow a space the light will cover. The distance from the light to the surface is a big part of the equation too – if the light is a 30° beam angle and is close to the surface it’s aimed at, it will create a small, bright pool of light. Move that same light further away, and it will create a broader, softer pool of light.
The beam angle describes the bright centre of the light, but most lights also produce a "field" of light. The field is the softer spill around the beam, and it isn't measured in the beam angle. You need to see the light on to know how wide the field is, and a wide field on a narrow beam light can leave you with unexpected glare or spill light in your lighting design.
With downlights, anything over a 40° beam angle is generally going to be glary, so it's best to avoid directional lights with a very wide beam. Very wide beam lights are often used when a ceiling is filled with downlights for "general lighting". If you're on this path, try rethinking your lighting design before you end up with ceiling acne! A professional lighting designer can be great support for suggesting different ways to light a room.
Narrow beams (10° up to 24° is usually considered narrow) are useful for bringing light down from high ceilings and for creating dramatic features.
The first step is to check the light fitting spec sheet for beam angle information. In my experience, though, you need to see a working sample to be sure. Or you can ask the supplier to take a photo of the light grazing hard against a wall, so you can see the beam and the field.
When you're creating a highly specific effect, it matters whether the beam is sharp or soft, wide or narrow. With narrow beams we often see poor beam control, and that can steal the drama you are trying to create. With light, it's important to know what you're working with! (If you'd like to understand more about this, our Lighting 101 workshop might be of interest to you.)
3. CRI: the number that decides whether your dinner guests look green
Usually, people only think about art and soft furnishings when they consider colour, but did you know that each of us reflects colour?
This means that if we are in poor quality light, we're likely to look green, or grey, or any number of colours that make us look unwell!
Making sure the lights you use will render the colours of your body, your room and your interior design is critical to ensuring your spaces feel crisp, welcoming and "right" when you turn on your lights.
The Colour Rendering Index (CRI) measures how well a light shows colour. It's one of the most important numbers on a spec sheet, and one that most people have never heard of.
Before LED, nobody needed to check CRI at home, because incandescent and halogen globes rendered colour almost perfectly. LED changed that.
In homes, CRI 90+ is our benchmark for living spaces. If you'd like to go further, a TM-30 report shows the fidelity and balance of a light's colour, and even whether the light skews pink or green. TM-30 is a topic for another day, but worth researching if you’re keen to understand the intricacies of colour in light.
4. Colour temperature: pick one, and make the rangehood obey
What colour does your light appear to be when it's on? Warm and golden, or cool and blue? That's colour temperature (CCT), measured in Kelvin (K).
Preferences for light colour vary around the world. At MINT, we aim for a consistent 3000K "neutral warm white", which is essentially white light with a slight warmth.
In cooler climates, people often prefer warmer light at home, closer to 2700K. That's still a quality white light, with a golden hue (definitely not yellow). We often use 2700K for decorative lighting, combined with 3000K general lighting.
The colour temperature you choose is up to you, but do NOT mix warm and cool!
Rangehoods are the killer for this in homes. Every light in the kitchen can be perfect, but if the rangehood comes with a standard 6000K cold white light, suddenly there's a spaceship in the middle of the kitchen every night before dinner!
Even 3000K from two different brands won't always look the same. Side by side, one light can look slightly pinker or greener than the other, so where you can, keep to one brand within the same view.
5. Watts: handy for the power bill, useless for brightness
Watts tell you how much power a light fitting uses and used to be our key selector for lighting at home, because they were how we gauged the brightness of a globe.
With LED, lumens are what tell you how bright a light is.
Watts still matter for energy use. The easiest way to compare two light fittings is efficacy, measured in lumens per watt (lm/W). The higher the efficacy, the more light you get for the power you're paying for.
In Australia, the National Construction Code allows no more than 5W/m² for lighting in a home. MINT designs usually sit between 2.5 and 3.5W/m². That figure includes every light source in the home, not just the lights that are on at any one time.
6. GLARE: the one you can't read off a spec sheet
When you turn on the lights and flinch, that's glare.
Glare is the hardest measurement to evaluate from a manufacturer's spec sheet. Some manufacturers provide a UGR (Unified Glare Rating), which is a handy starting point for “is this light likely to be glary or not”, but ultimately it’s a little bit BS as the UGR calculations was designed for offices with regular grids of lights, so it tells you very little about a single downlight over your dining table.
Just like beam angles, the only real way to judge glare is to see the light turned on.
At MINT, we have a rule: if a directional light has a diffuser, we won't use it. NO PANCAKE DOWNLIGHTS!!!!
I have no idea why people insist on making these awful pancake downlights, but they do, so we have to talk about them. A diffused downlight puts a glary disc in your ceiling that does very little for the room, and often barely pushes enough light down to read at the table.
I understand why pancake downlights are used everywhere (cheap, easy to install, hide bad plaster joins with bad light, did I mention cheap?), but they are awful to live with, and I would love nothing more than to never see another one in a home again!
A seventh, for the overachievers: flicker
Some LEDs flicker faster than you can see, but your eyes and brain still notice, and you pay for it in headaches and tired eyes at the end of the day.
Most of the time, the cause of flicker is the driver (the little box of electronics that powers the LED). Look for light fittings with high quality drivers that have been tested to be "flicker free". As a rule, the cheaper the light fitting, the cheaper the driver, and the more flicker you'll get. Cheap light globes can be real offenders too, so the $4 bargain bin globe for your bedside lamp is a false economy.
Quality always matters with lighting, and it especially matters with flicker, because you can't see flicker in the showroom and you'll live with it every night. If you're suspicious of a light at home, film it in slow motion on your phone. Dark bands rolling across the screen are a good sign the light is flickering (or that your camera settings are off, so use what you learn as a starting point for more research, not an absolute measurement).
To learn a little more about flicker (and why you shouldn't give up on LEDs because of it), read Your Lighting Designer Is Not Trying To Gaslight You About LEDs.
Putting it together
If you check these measurements for every light fitting you consider, you'll be well on the way to getting control over your light and crafting a beautiful experience at the flick of a switch.
If checking six things on every light fitting in your home sounds like a fun weekend, you're my kind of person (and Light School was made for you). If you'd rather not get that up close and personal with light fittings, you can hand the whole question over to the experts.
MINT's lighting designers love this kind of detail and have years of experience choosing great light. We don't sell light fittings, so our only interest is in finding the ones that will give you the light you want. Talk to us about your home →