They cost almost the same — the B4 is S$120 and the K3 S$130 at the time of writing — so price will not decide this for you. The job will. The B4 prints 4×6" courier labels and runs on a battery; the K3 does neither, but prints more than twice as fast from mains power and also handles receipt paper. Neither is the upgrade of the other.
If you ship parcels, it has to be the B4
The B4 takes label stock up to 110mm wide, which covers the standard 100×150mm (4×6") courier label. The K3 stops at 82mm. No setting changes that, and it is the single most common reason someone buys the wrong one of these two. If your batch is airway bills, stop reading and get the B4 — see the B31 and B4 size guide or go straight to the 50–110mm roll range.
If you print in volume, it has to be the K3
The K3 runs at 180mm/s against the B4's 80mm/s, and it is rated for up to 150 labels a minute. On a run of a few hundred price tags that is the difference between a coffee break and an afternoon. It is also built for the duty: continuous printing up to 80km, versus a printhead rated around 50km on the B4.
Pair either with a spreadsheet import and the gap gets more obvious — our guide to printing labels from Excel works on both, but only one of them clears a long queue quickly.
Power and portability
The K3 runs from a mains adapter. That is a feature, not a limitation: for batch work a battery is just something that runs flat halfway through. But it does mean the K3 lives where you put it — 1220g and 232 × 145 × 148mm.
The B4 has a 2000mAh battery and weighs 757g in a body about half that size, with the roll bin built in. If you pack orders in one room and label stock in another, or take the printer to a market stall, that matters more than speed.
The K3 also prints receipts
Less well known, and worth knowing if you run a counter: as well as die-cut label rolls and fanfold stacks, the K3 runs plain continuous receipt paper. One machine covers cafe price tags and shelf tickets during the day and customer receipts at the till. The B4 does labels only. Our K3 and H1S guide lists the label sizes; the K3 roll range runs from small multi-lane stock up to 80×160mm.
What they have in common
Both print at 203dpi, both are direct thermal so there is no ink, toner or ribbon to buy, and both connect over Bluetooth to the NIIMBOT app on iPhone, Android and Windows. Both handle barcodes, QR codes and batch printing. On print quality alone you would not be able to tell their output apart.
So which one?
Buy the B4 if you print courier labels, if you need to carry the printer, or if you want the widest stock in the range. It is the pick for a fulfilment bench that also packs parcels. Stock up from the B4 label range.
Buy the K3 if your printer sits on a desk, your batches are long, and receipts are part of the job. If you want K3-class width but need it portable and battery-powered, the B31 at S$96 covers 75mm — our B31 vs B4 piece covers that decision.
Still weighing up the whole range? Our 2026 buying guide works through it by label width. Browse the full inkless range; every printer ships from our Singapore warehouse with a 1-year local warranty.