Strapping Size Guide
Which strap do I need?
Answer four questions and we’ll show you what we stock in Miami that matches. No jargon required — if a term is new to you, there’s a plain-English guide further down.
Plain-English guide
Four things buyers ask us every week.
1What does 1/2" mean, and how do I measure what I already use?
The fraction is the width of the strap — the flat face you can see, measured across. Nothing else. A 1/2" strap is half an inch wide.
Every polypropylene width we stock, drawn to scale against each other
This is the actual size difference between them. Tap one to see what we carry in it.
Measure your strap against this screen
Every screen is a different size, so calibrate first. Hold any bank or ID card flat against the screen and drag until the outline matches it exactly — all cards are the same standard size.
One page with every width at true size. Lay your strap on it and read off the answer — the same way a shoe size chart works. It has a check ruler on it so you know the printer didn’t scale the page.
Or just type what you measured
| Nominal | Inches | Millimetres | Commonly used for |
|---|---|---|---|
| 1/4" | 0.25" | 6.4 mm | Light bundling |
| 3/8" | 0.375" | 9.5 mm | Cartons, light machine strapping |
| 1/2" | 0.5" | 12.7 mm | The most common size — general duty |
| 5/8" | 0.625" | 15.9 mm | Heavier loads |
| 3/4" | 0.75" | 19.1 mm | Heavy loads |
| 1 1/4" | 1.25" | 31.8 mm | Heaviest loads, steel replacement |
Two other numbers show up on a strap label. Test (for example “600 Test”) is the break strength in pounds — the force at which the strap fails in a lab pull test. It is not a safe working load; the usable tension is a fraction of it. Core (for example “8x8") is the roll’s centre: see question 2.
2Hand grade vs machine grade
This is about how the strap gets applied, not how strong it is.
Hand grade
You apply it yourself with a tensioner and a sealer, or with a battery or pneumatic power tool.
- Heavier, stiffer strap
- Made to be pulled tight by hand and crimped with a seal or buckle
- Comes on a 16x6 core for a floor dispenser, or 8x8
We stock hand grade in 1/2", 5/8" and 3/4".
Machine grade
It feeds through an automatic or semi-automatic strapping machine, which tensions and heat-welds it for you.
- Thinner, with tighter dimensional tolerances and less camber so it doesn’t jam
- Much longer rolls — fewer coil changes
- Comes on an 8x8 or 9x8 core to fit the machine’s magazine
We stock machine grade in 1/4", 3/8" and 1/2".
What 8x8, 9x8 and 16x6 actually mean
Two numbers, both in inches: the hole in the middle × how wide the roll is. Drawn here to scale against each other.
3Polypropylene vs polyester
Both are plastic strapping, and they are not interchangeable. The real difference is what happens to the tension after you walk away.
| Polypropylene (PP) | Polyester (PET) | |
|---|---|---|
| Holding tension over time | Relaxes — loses tension as hours and days pass, faster in heat | Holds tension far longer, including through temperature swings |
| Stretch at working tension | More give (roughly 4–10%) | Less give (roughly 2–6%) |
| If the load pushes outward | Poor — it yields and keeps stretching | Good — it resists and holds the load in |
| If the load settles a lot (over 2%) | Better of the two — its elasticity pulls the slack back in | Poor — little stretch left to take up the movement |
| Outdoors | Short exposure only; UV degrades it | Handles sun and moisture far better |
| Cost | Lower | Higher per foot |
| Typical use | Cartons, bundles, totes, palletised boxes, local delivery | Heavy or rigid loads, long transit, long storage, a replacement for steel strapping |
One case goes the other way. A load that settles hard — compresses or loses volume by more than about 2% — is the one place polypropylene does better. Polyester has little stretch left to take up that slack, while polypropylene’s elasticity pulls it back in. Neither is ideal; tell us and we’ll work through it with you.
4Embossed vs smooth polyester
Ask three suppliers and you will get three answers, most of them sales pitches. Here is what the manufacturers’ own published literature actually supports.
Embossed
A fine pattern rolled into the face near the end of manufacturing.
- Uses less material for the same stated size and gauge. The pattern raises the strap’s height, so a given nominal thickness holds slightly less polyester in its cross-section
- Tensions with less effort — only the raised pattern touches, so there is less friction as the strap runs over itself
- Built for packages with sharp edges — lumber, panel, crates
This is what we stock.
Smooth
A flat face with full contact.
- Full cross-section of polyester at the stated gauge — more material than embossed of the same nominal size
- Welds faster — full surface contact heats quicker in a friction weld
- Specified for metals and cans — finished surfaces you don’t want marked
Not a stock item — ask us and we’ll quote it.
• Sharp edges on the load — lumber, panel, crates — embossed.
• Finished surfaces that must not be marked — metal, cans, coated panel — smooth.
• The most polyester for a given stated gauge — smooth.
• Already running one of them without trouble — keep running it, and check your machine’s manual before you switch.
Machine grade: 1/4", 3/8", 1/2" · Hand grade: 1/2", 5/8", 3/4"
packstrapusa.com/quick-order
Still not sure? Send us what you have — the old label, a photo of the roll, or the machine model — and we’ll tell you exactly what it is.
Ask us