Portable monitor specs: what to look for before you buy

Portable monitors cluster around 14 to 16 inches because that is what fits in a laptop bag next to a laptop. Going bigger buys real desktop space and costs portability: an 18 inch panel is a different thing to carry, and it usually needs a sturdier stand or a case that doubles as one. Going smaller keeps the bag light but a 13 inch second screen adds less usable area than most people expect.

Match the size to the laptop rather than to the maximum you can lift. A 14 inch monitor next to a 14 inch laptop gives a tidy, symmetric setup; a 16 inch next to a 13 inch laptop looks mismatched but gives noticeably more room for a spreadsheet. If the monitor will mostly stay on a desk, buy the size you want, because the weight only matters on the days you travel.

1080p on a 15 inch panel is about 147 pixels per inch, which is perfectly usable but visibly soft next to a modern laptop. 2560 x 1600 on a 16 inch panel jumps to roughly 189 ppi and looks sharp, and 4K on 15.6 inches reaches about 282 ppi. Higher resolution costs more, drains more power and can force scaling, which reduces the usable area you thought you were buying.

Think about what you will read. Text work benefits from density, video and gaming benefit from refresh rate, and a 4K panel driven by a laptop's integrated graphics may struggle to hit a smooth frame rate in games. 2560 x 1600 at 16 inches is the sweet spot for most people, and 1080p is fine for a secondary screen showing chat and reference material.

Most portable monitors are 16:9, matching televisions and most video. A 16:10 panel is slightly taller for the same width, which gives roughly 11 percent more vertical space: a few more spreadsheet rows, a little more document, less scrolling. It also tends to match modern laptops, which have largely moved to 16:10 and 3:2.

The catch is resolution and scaling. A 16:10 panel at 2560 x 1600 is a natural pairing, but a 16:10 panel at an odd resolution can force awkward scaling. If you mostly watch video, 16:9 fills the screen exactly; if you mostly read and write, the taller panel earns its keep. Either way, check the native resolution rather than assuming it from the diagonal.

IPS is the default and the right choice for most buyers: accurate enough colour, wide viewing angles, no burn-in risk and a low price. VA panels appear occasionally and offer deeper blacks at the cost of viewing angles, which is a bad trade on a screen you look at from an angle. TN is essentially gone from this category and should stay there.

OLED is the interesting upgrade. Per-pixel lighting gives true blacks and near-instant response, and the contrast figure is orders of magnitude beyond any LCD. The costs are price, and the risk of burn-in if you leave a static taskbar on it for hours every day. For video, games and photo review, OLED is visibly better; for a document screen left open all day, IPS is the safer buy.

Most portable monitors run at 60Hz, which is fine for everything except fast motion. 120Hz and 144Hz panels make scrolling and cursor movement noticeably smoother, and they matter for gaming. The catch is that the source has to drive them: a laptop outputting 60Hz will not make a 144Hz panel run at 144Hz.

Response time is the companion figure. A 144Hz panel with a 13ms response time will smear in fast movement, while a 4ms panel at the same refresh stays clean. Look for grey-to-grey figures and be sceptical of anything quoted without a measurement method. If you are not gaming, save the money and take a better panel at 60Hz instead.

Brightness is quoted in nits, and the range in this category is enormous: 250 to 300 nits is common, 400 is good, and 1000 is exceptional. Outdoors or beside a window, 300 nits is a struggle and 250 is unusable. Indoors in a normal room, 250 to 300 is perfectly comfortable.

Higher brightness costs battery, both in the panel itself and in the power your laptop has to supply over the cable. A 1000 nit panel run at full brightness will drain a laptop noticeably faster than a 300 nit one. Buy for where you actually use it: 400 nits covers most travel, and 1000 nits is for people who genuinely work outside.

Colour gamut describes how much of a colour space the panel can show: 65 percent sRGB is dull, 100 percent sRGB is normal, and 100 percent DCI-P3 is wide. Colour accuracy is a separate claim about how close each colour lands to the target, usually written as Delta E, where lower is better and under 2 is good enough for photo work.

A panel can cover 100 percent of a space and still be inaccurate, or be accurate within a small gamut. For office work neither figure matters much. For photo editing, buy for Delta E under 2 and at least 100 percent sRGB, and check whether the manufacturer publishes a calibration report. Wide gamut without accuracy just means confidently wrong colours.

The best portable monitor is the one that needs a single cable. USB-C with DisplayPort Alt Mode carries video, and if the port also accepts power delivery the laptop can charge over the same cable. Mini HDMI is the usual fallback for a camera, console or older laptop, and it needs separate power, which means two cables and a wall adapter.

Count the USB-C ports rather than assuming one. Two full-function USB-C ports let you feed video into one and power into the other, which is how a phone or a low-power laptop drives the screen without draining. A 3.5mm audio output is worth having on a panel without speakers, and it is the only way to get sound out of a monitor that has none.

A portable monitor draws between about 5W and 15W depending on size and brightness, and it takes that power either from the laptop over USB-C or from a wall adapter. Power pass-through is the feature worth checking: a monitor that accepts 65W and passes some of it on lets a single charger feed both the screen and the laptop.

Be realistic about the budget. A laptop with a 45W charger and a monitor drawing 12W is fine; a gaming laptop that wants 180W will not charge from a monitor's pass-through port, it will just discharge more slowly. If you travel with one charger, buy a monitor with a pass-through rating that matches it, and check the direction of the port rather than assuming it is bidirectional.

Portable monitors run from about 0.6 kg to 1.2 kg, and from 7mm to 17mm thick. Under a kilogram and under 10mm is genuinely bag-friendly; a 1.2 kg panel with a 19mm folded thickness is a different proposition, especially once you add the cover and a cable. Check whether the quoted weight includes the cover, which it usually does not.

The stand matters as much as the weight. Many panels rely on a folding cover that props them at one or two angles, which is fine on a table and useless on a lap. A kickstand built into the back is more adjustable, and a VESA mount opens up a proper arm. If the screen will live on a desk, weight stops mattering and the stand starts to.