Polypropylene, not vinyl
The two brown tapes on the shelf look identical. Polypropylene is the thinner, crackly one that comes off the roll with a sharp noise. Vinyl, sometimes sold as PVC, is thicker, quieter and feels better in the hand, which is why people reach for it.
The difference shows up in the cold. Vinyl adhesive stiffens as the temperature drops and its grip on cardboard falls away with it. A Luton van at seven in the morning in February is a cold box, and a carton whose top seam opens as somebody lifts it is how a set of glasses ends up on a driveway. Polypropylene keeps working. We use nothing else.
There is a low noise polypropylene as well, which uses a different adhesive to lose the crackle without losing the grip. Worth it if you are packing in the evening with other people in the house.
What width and length
48mm is the trade standard and the only width worth buying. Narrower tape means more passes to hold the same seam, which uses more tape and more of your evening. Wider tape is for palletising, not for cartons.
Length is sold at 50m, 60m or 66m per roll. The price per metre usually improves as the roll gets longer, so the 66m rolls tend to be the better buy if you are moving a whole house.
How many rolls
Work on one roll per fifteen boxes, with a floor of three. An average three-bedroom move at 70 to 90 boxes therefore lands at five or six rolls, and you should buy one more than that. Tape gets used on far more than boxes: taping drawers shut, bundling curtain poles, holding bubble wrap round a mirror, strapping a bin liner over a lampshade.
Some tape comes with your boxes on a full move with us. Treat that as a start rather than the total.
How to tape a box so it holds
Tape the bottom before you fill it, not after. One strip straight down the centre seam, then one across each end so the short flaps cannot fan open under load. That is the H pattern, and it is what turns a box into a container rather than a sheet of folded card. Repeat it on top when the box is full.
Do not rely on interlocking the flaps without tape. It holds fine on a table and gives way the moment the box is lifted by its hand holds.