Strap Width and Length by Bundle

A strap has to go around the bundle, so the length it needs is the bundle circumference. Circumference is pi times diameter, which for a two inch bundle is about 6.3 inches.

On top of that you need overlap, because hook only grips where it lands on loop. Two inches is a workable allowance for most consumer straps: enough to grip properly, not so much that the tail flaps. Some designs pass through a slot or a buckle and double back, and those need more.

So a two inch bundle wants a strap of about 8.3 inches. A six inch cable tie, the most common size sold, closes a bundle of about 1.3 inches diameter with that allowance. That is a handful of desk cords, not a coiled extension cord.

Gather the cords in your hand the way you intend to strap them and measure across the widest point. That is your diameter, and it is always larger than people guess because cords do not pack tightly.

If the bundle is not round, and a bundle of stiff cords rarely is, measure the widest dimension and treat it as the diameter. The result overestimates slightly, which is the direction you want to be wrong in.

For a coiled extension cord, the coil diameter is not the bundle diameter. What the strap goes around is the thickness of the coil wall, which is roughly the cord diameter times the number of turns stacked at that point.

Length decides whether a strap closes. Width decides whether it stays closed under load. A narrow strap on a heavy coil concentrates all the holding force on a thin band, and the coil works itself loose as it swings.

Half inch and narrower is desk work: a few cords behind a monitor that nothing pulls on. One inch is the general garage width and covers extension cords and hoses. Two inch straps are for awkward loads that want to spring apart, such as lumber, mats and camping gear.

Width also affects how the strap behaves on a hook. A wide strap distributes the load over more of the hook and is far less likely to slide off the end of it.

Plain hook and loop straps hold at whatever length you set them and do not pull the bundle tighter. That is the right behavior for cords, where you want snug rather than compressed.

Elastic cinch straps with a buckle keep tension as the bundle settles, which suits loads that shift. The trade is that they can be pulled genuinely tight, and tight is not what a cord bundle wants.

A cut-to-length roll solves the sizing problem outright. You measure the bundle, cut the length the arithmetic gives you, and you are not choosing between a strap that is two inches short and one that has a foot of tail. A 32 foot roll cut into 8 inch straps yields 48 of them.

Hook and loop fails by contamination long before it fails by wear. Sawdust, grit and pet hair pack into the loop side and stop the hook engaging. A stiff brush recovers most of it; a strap that lives on a garage floor will not last.

Adhesive-backed clips fail at the adhesive, not at the clip, and they fail faster on textured, dusty or cold surfaces. Clean and warm the surface before sticking, or accept that it will let go in winter.

The last failure is the one that matters most: using a strap to tidy a cord that should have been taken out of service. A strap makes a damaged cord look neat. It does not make it safe.