We make a handheld device, so treat what follows accordingly. We have tried to write the comparison we wanted to read before we built one — including the parts where handhelds come off worse.
Coverage: panels win, clearly
This is the real difference and there is no arguing it.
A full-size panel covers a large area at once. A handheld covers a small area, so you either move it around or treat one region per session. If you want to cover a large area in a single sitting, a panel does that and a handheld does not.
Anyone selling you a handheld as equivalent to a panel on coverage is not being straight with you.
Output: closer than you would think
Coverage and irradiance are different things. Irradiance describes intensity at a point, not how much area you can reach.
A well-built handheld can match or exceed a panel's irradiance at the same distance, because it is concentrating output over a smaller area rather than spreading it. Ours measures 40 mW/cm² at 10 cm with both wavelengths running.
The honest framing: a handheld can match a panel on intensity and cannot match it on area.
Practicality: handhelds win
A panel is furniture. It needs floor space, a wall, or somewhere to lean, and it stays where you put it. Setting up is part of using it, and setting up is what people stop doing around week three.
A handheld is a thing you pick up. Ours is 244 grams and 140 × 70 × 29 mm — smaller than a paperback. It lives in the case it ships with. If it also stands on its own, you can set it down and leave it running instead of holding it.
Whether this matters depends entirely on you. Some people build a routine around a dedicated space. Most do not.
Travel
Panels do not travel. Handhelds can — but check the battery.
Airlines limit lithium batteries in cabin baggage to 100 Wh. Ours is 18.5 Wh, well inside that. Lithium batteries are not permitted in checked luggage at all, on any airline, so anything with a battery goes in the cabin with you or stays home.
Price
Full-size panels typically run from several hundred dollars into the thousands. Handhelds sit well below that. Ours is $499.
Cheaper handhelds exist — plenty at around $100 to $150. What you are usually paying more for is published measurements, both wavelengths in meaningful numbers, a warranty you can actually claim on locally, and someone to call. Whether that is worth the difference is your call, but it is worth knowing that is what the difference buys.
So which one
A panel makes sense if you want to cover a large area in one session, you have somewhere to put it permanently, and you are not planning to take it anywhere.
A handheld makes sense if you want to target specific areas, you would rather not dedicate floor space to it, you travel, or you have watched a larger device gather dust before.
Neither makes sense if the brand will not tell you the measured irradiance and the distance it was measured at. That applies equally to both.
Read: what irradiance actually means →
See the full specifications →