How many lumens does a projector need?

Brightness is a factor in every display technology but is particularly important to projectors. With a conventional TV or monitor screen, your eyes are receiving light emitted directly from the screen itself.

With a projector, they’re receiving light emitted from the projector’s light source, filtered and coloured by its LCD or DLP display engine, transmitted through a lens over several metres, and then reflected from a wall or screen. At every stage of the process, you’re losing brightness, which impacts the clarity, contrast and colour of the image. As a result, brightness counts.

Lumens explained

“Brightness is a subjective concept,” says Damien Trendall, projector line of business manager for manufacturer BenQ, which makes one of our favourite gaming projectors, the BenQ X500i (pictured below).

“The term that is more commonly used by experts when discussing light is ‘luminance’ or ‘lumens’ which is essentially the total amount of light produced by a light source per unit of time.”

Officially speaking, the lumen (lm) is the unit of luminous flux, or a measure of the power of the visible light emitted by a source, weighted according to a model of the human eye’s sensitivity to various wavelengths of light. It’s standardised by the International Organization for Standardization, or ISO.

However, just to confuse you, it’s not ISO lumens that we usually refer to with projectors. Instead, most manufacturers quote figures in ANSI lumens, averaging different measurements of light taken at different positions in accordance with the IT7.215 standard to give a final figure. With some manufacturers using ISO lumens but many others using ANSI, it pays to check which figure they’re using before making any meaningful comparisons.

What’s more, the stated lumens figure given doesn’t necessarily tell the whole story, as Trendall notes.”‘In reality, the light from the projector’s light source diminishes quite a bit before it is even projected since it’s transformed by the projector’s imaging mechanism as it passes through,” he says.

“What this means is that on average the ANSI lumen value of the projector itself is usually only about 30% of the lumen value of its light source, so a projector with a 3,000-lumen light source might only produce 900-lumen light.”

As some brands list the lumen value of the light source, this can again make comparisons tricky.

Does the lumen count influence throw distance and image size?

Yes. As Trendall puts it, “The viewer’s eyes are not directed at the lamp itself, but at the surface that the projector’s light is being projected on (e.g. a screen).

“And since a projector’s light reflects off a surface, the size of that surface affects the brightness of the final image. A high lumen value can give a vastly different level of brightness to the eye depending on how far it is spread out.”

To see this in action, point a projector with a specific lumen output and throw ratio at a screen. By moving the projector backwards and forwards you increase and decrease the size of the projected image (with the throw ratio defining how much image you get per metre of distance).

The further away the projector is, and the more that light spreads, the less intense that light will be. This isn’t a huge issue when projecting a 40 to 60in image from a distance of one to two metres, but it’s a bigger deal with a larger screen size.

As Matthew Glynn, product marketing manager at Hisense puts it, it’s “particularly crucial when projecting large-format images of 150in and beyond. Without sufficient brightness, image sharpness deteriorates, particularly around the edges, leading to a compromised viewing experience.”

Hisense knows more than a thing or two about big, bright projectors, with the five-star Hisense C2 Pro (pictured above) able to deliver 2,600 ANSI lumens and create images up to 300in.

How will a room’s light conditions affect the lumens needed?

The brighter the ambient lighting in a room – whether artificial or daylight – the harder it is for the light from the projector to compete as it bounces off the screen, with the ambient light drowning the projected image and reducing levels of contrast and colour.

Most projectors below 500 lumens will struggle to produce a visible image even in low-level lighting, and you’ll need closer to 1,000 lumens to see much inside during daylight hours. Even then, you’ll see a loss of contrast and colour in comparison to viewing in near-dark conditions. You really need 1,500 lumens or more to get a good picture between sunrise and sunset, and it still won’t be ideal.

What about the screen or surface being projected onto?

The screen also makes a huge difference. If you’re projecting on a wall with a matt white surface then you’re going to lose more lumens as the light reflects from it. With a dedicated projector screen, it all depends on the material used for the screen and any treatment the surface has been given.

Most screens specify a 1.0 gain, meaning they reflect the same amount of light as a standard white reference board with a magnesium oxide coating. However, a screen with a 1.5 gain will reflect 50% more light, while a screen with a 2.0 gain will reflect twice as much light.

This makes it sound like high-gain screens could be the answer to your problems, but they have a few issues. Firstly, they reflect more ambient light and may make blacks and darker shades look lighter. Secondly, parts of the image will tend to be brighter or darker depending on where you sit. From dead centre, the middle area of the screen will usually be brighter than the outside portion. Finally, high-gain screens may not treat colours equally, sometimes resulting in a colour cast.

There is another option that can help: an ambient light-rejecting (ALR) screen. These use a fabric with a Fresnel treatment, which rejects the ambient light while concentrating the light coming from the projector. This gives you a brighter, higher-contrast image that’s clearer in artificial light or daylight, but at a cost. Even basic ALR screens cost between £500 and £800.

Do outdoor projectors need more lumens?

If you’re projecting outside during daylight hours, you’re going to need a lot more lumens. Realistically, we’re talking 3,000 to 5,000 lumens just to get a visible image. For most home cinema projectors, that’s not a realistic goal.

At night, it all depends on the time of night, cloud cover and the phase of the moon, but you can get a watchable picture with 300 to 500 lumens and a good picture with 600 to 1,000 lumens. For reference, our favourite outdoor projector, the Anker Nebula Mars 3, has a stated maximum ANSI lumens of 1,000.

“For outdoor use, I would say the higher the lumens the better, particularly in the warmer months,” says Shaun Robinson, product manager for home cinema at Epson UK.

“This is essential to combat pesky ambient light sneaking in, ensuring the image remains visible and clear. And if you want an even more optimised outdoor setup, I would recommend using a pull-up screen.”

Do you typically pay more for more lumens?

Usually. You will find some very affordable projectors that use a conventional lamp and output 1,000 to 2,000 lumens or more, but most budget or portable projectors use an LED light source capable of outputting between 100 and 500 lumens. The Anker Nebula Capsule 3 is one such option, delivering 200 ISO Lumens for under £500.

Move up the price scale and you’ll find models with more powerful or sophisticated LED engines that can reach 800 lumens, then laser or hybrid LED/laser models like the XGIMI Horizon Ultra that can dish out well over 1,500 lumens. As these will also offer other features that improve image quality, it’s worth spending the extra.

Do more lumens equate to better image quality?

“The brightness level in a projector is very important,” says Epson’s Shaun Robinson.

“It directly impacts the visibility, overall image quality, detail and colour accuracy – all of which are essential to having a positive viewing experience.”

Lack of brightness can have the opposite effect. “If the brightness of the projector is too low” he adds, “images can appear washed out, dull or lacking in detail, particularly in darker scenes.”

“Brightness is a fundamental factor in laser projection, directly impacting image clarity and the overall viewing experience, ” says Hisense’s Matthew Glynn.

“A well-calibrated level of brightness ensures scenes appear vivid and sharp, enriching immersion for the viewer. However, achieving high brightness levels without the appropriate hardware and software optimisations can lead to diminished picture quality and viewing fatigue.”

Brightness is particularly important if you’re planning to watch HDR content or play video games. As Robinson notes, “HDR relies on a broad range of brightness and contrast to deliver the deeper blacks and more vibrant colours. Video games can also benefit from increased brightness, as it enhances the details in the games, and, in turn, the responsiveness.”

All the same, a high brightness level isn’t a definite cure-all, as BenQ’s Damian Trendall explains. “The brightness of an HDR projector, unlike HDR monitors, is not based on fixed values from the signal assigned to it, but varies depending on the distance between the projector, and the screen, screen size and the material of the screen.”

Instead of simply going for high brightness levels, projector manufacturers work to optimise the image to maximise dynamic range for different screen types, images and image sizes, so you’re getting the best possible HDR picture at all times.

Final verdict: How many lumens does your projector really need?

This depends on how and where you use your projector and your budget, but – as a rule of thumb – brighter is better, and will give you a more watchable image in more places.

With cheaper portable projectors designed for more casual viewing, 200 to 500 lumens will suffice, but look for more if you plan to use the projector outside, or if you’re serious about getting a high-quality image outside of a pitch-black room.

That’s where the 1,500 to 3,000 lumens of lamp and laser projectors come through, delivering a bright, cinematic image that can bring your TV shows, games and movies to life.