Twine is the cheapest input on the farm that can shut down your whole day. Buy the wrong knot strength and the knotter misses; buy the wrong length and you're changing balls every forty bales; buy sisal when you needed poly and you'll find out in the shed next spring. Yet almost nobody explains what the numbers on the box actually mean.
This guide decodes the label, matches specs to baler types, works through the sisal-versus-poly decision honestly, and settles the billhook argument that comes up every single season. If you're weighing twine against net wrap on a round baler, start with our net wrap vs twine cost comparison — this article is about buying twine well once you've decided you need it.
How to read a twine label
Nearly every North American twine box uses the same convention, written as length-knotstrength or length/knotstrength:
7200-190 = 7,200 feet per ball · 190 lb knot strength
4000-440 = 4,000 feet per ball · 440 lb knot strength
Two things follow from that, and they explain most of the confusion:
- The two numbers move in opposite directions. A ball of twine is sold by weight, so more feet means thinner twine and less strength. 9,600 ft at 170 lb and 7,200 ft at 190 lb are close to the same amount of material — one is stretched further.
- Knot strength is not tensile strength. The rating on the box is measured with a knot tied in it, because that's where twine actually breaks. Some imported product quotes straight tensile strength instead, which reads 20–30% higher for the same twine. If a spec looks unusually strong for the price, check which number is being quoted.
You'll also see a "runnage" figure on some brands — feet per pound. It's the same information in another form, and it's the honest way to compare boxes when the ball weights differ; manufacturers such as Bridon publish length, knot strength, and runnage together for exactly that reason. Sisal has historically been standardized at 9,000 ft per ball with a nominal 40 lb bale weight, though several brands now ship 35–36 lb bales at the same footage.
Knot strength by baler type
Match the twine to the machine, not to whatever's on sale. Density is what drives the requirement: a 60 lb small square and a 1,600 lb big square put wildly different loads on a knot.
| Baler type | Typical length per ball | Knot strength | Common label |
|---|---|---|---|
| Round baler (poly) | 16,000–20,000 ft | 110–130 lb | 20000-110 |
| Small square, standard | 9,000–9,600 ft | 130–170 lb | 9600-170 |
| Small square, heavy / dense | 7,200–9,600 ft | 170–210 lb | 7200-190 |
| Medium square (2- and 3-tie) | 5,000–9,400 ft | 210–300 lb | 6500-240 |
| Big square (3×3, 3×4, 4×4) | 3,500–5,000 ft | 350–700 lb | 4000-440 |
| Sisal, small square | 9,000 ft | ~130–190 lb | Sold by bale weight |
Three practical rules on top of that table:
- Start with what the operator's manual specifies, then move up only if you're actually breaking twine — not because heavier feels safer.
- Heavier twine is stiffer twine. It feeds differently through the tensioners and needles, and a knotter tuned for 170 lb material can start missing on 210 lb. If you jump a grade, expect to re-set tension.
- Don't mix grades mid-field. Running two different twines through the two sides of a small-square knotter is a reliable way to get one clean knot and one loose one on every bale.
Sisal or polypropylene?
This is the real decision, and it isn't about strength — both are plenty strong for their intended machines. It's about what happens to the twine after the bale is fed.
| Factor | Sisal | Polypropylene |
|---|---|---|
| Cost | Roughly 2× poly in the US | The value option |
| Decomposes | Yes — natural fiber, rots down | No, essentially forever |
| Manure spreader / field cleanup | Safe — breaks down, won't wrap shafts long-term | Wraps beaters and augers; must be picked up |
| Moisture | Absorbs it; weakens in damp storage | Unaffected |
| Long outdoor storage | Degrades on the bale, can let go | Holds; UV-inhibited grades hold longer |
| Rodents | More attractive to mice — it's plant fiber | Generally less chewed |
| Handling | Grippy, easy on gloved hands | Slick; cuts if you pull it bare-handed |
The unsentimental summary: sisal is worth the premium when the twine is going to end up somewhere you can't retrieve it — bedding that goes through a manure spreader, bales fed in a field, anything headed for compost. Poly wins on cost and on long outdoor storage, and it's the default for round balers and big squares because those bales need more holding force than sisal comfortably provides at the same diameter.
The permanence of poly is not a small thing. Operators regularly report digging up wads of plastic twine in fields that haven't been baled in fifteen years. If you run poly, budget the time to collect it — a barrel by the feed ring costs nothing and saves a driveline later.
The billhook question: do you need different knotters for poly?
This argument runs every spring, and the answer is more nuanced than either camp admits.
The manufacturers really do make different billhooks. John Deere and New Holland both catalog a sisal-specific billhook and a separate dual-purpose or multi-twine version. Pricing tells you which one they expect you to buy: multi-twine hooks run about $70–75 each, while the sisal-only hooks are often over $130 — a legacy part at legacy-part pricing.
But most operators run poly on sisal hooks without trouble. The practical experience is nearly unanimous: after adjusting twine tension for the slicker material, sisal-era billhooks tie poly fine on a well-maintained knotter. The changeover isn't the problem people think it is.
Solar-degradable twine: read the fine print
"Solar degradable," "photodegradable," and "UV degradable" twine is exactly what it sounds like — ordinary polypropylene made without the UV inhibitor that's added to standard twine. It isn't a different material and it isn't biodegradable in the compost sense. Sunlight simply breaks the polymer chains down until the twine crumbles.
That creates a genuine trade-off:
- The good. Twine left in a field breaks apart in roughly 90 days to a year of exposure instead of lasting decades. For grazing operations feeding in the field, that's a real reduction in cleanup and in the risk of twine reaching a cow.
- The catch. It degrades on your bales too. Anything stored outside past one season may have strings letting go when you go to move it.
- The other catch. Degradable twine tends to be stiffer than standard poly, and stiff twine feeds worse. If your baler is already fussy about knots, this is not the product to experiment with mid-season.
Our read: it's a good fit for hay that will be fed within the season, and a poor fit for anything carried over. If long outdoor storage is the plan, the whole twine strategy deserves a second look — see storing net-wrapped bales outside.
What twine actually costs per bale
Recent operator-reported pricing, useful as a sanity check on a quote rather than as a current price list:
- 9600-170 poly: around $27 per box (two balls)
- 10000/190 poly: around $33 per box
- 6500/240: around $26 per ball
- 4000/450 big square: around $28 per ball
- Sisal, 9,000 ft: around $50 per bale of twine at farm-store retail
A useful rule of thumb that holds across most poly grades: about $1.00 per thousand feet. Anything meaningfully above that is either a premium grade or retail markup; anything well below deserves a look at whether the quoted strength is knot or tensile.
To convert to cost per bale, work out your feet per bale. A small square tied twice at roughly 12 feet per tie uses about 24 feet, so a 9,600 ft ball ties around 400 bales — at $13.50 per ball, that's about 3.4 cents a bale. A round baler putting 15–20 wraps on a 5×6 bale uses roughly 280–380 feet, so a 20,000 ft ball covers 50–70 bales, landing somewhere around 35–55 cents a bale. Compare that against wrap cost per bale in net wrap cost per bale.
Storing twine so it's still good next season
Twine is cheap enough that people store it carelessly and expensive enough that it hurts when a season's worth is ruined. Three habits solve nearly all of it:
- Keep mice out. This is the number-one killer of carried-over twine, and sisal is the bigger target. Store partial balls in lidded buckets or sealed totes; a few mothballs in the bucket is the old trick that still works.
- Keep it out of the sun. Even UV-inhibited poly loses strength sitting in a sunny shop window all summer. Degradable twine will be measurably weaker after one exposed season.
- Keep it dry — especially sisal. Sisal absorbs moisture, and damp sisal both weakens and starts to rot in the ball. Poly doesn't care about water but does care about heat cycling near a shop ceiling.
Where twine stops making sense
Twine is the right answer for every small square and for big squares, where there's no alternative. On a round baler, the calculus changed a long time ago — and unusually for a farm argument, there's clean research on it.
A USDA-ARS and University of Wisconsin storage trial compared large round bales bound with sisal twine, plastic twine, and net wrap over 5- and 12-month outdoor storage. Average dry matter loss across all trials was 19.5% for sisal twine, 11.3% for plastic twine, and 7.3% for net wrap. Net-wrapped bales consistently held less moisture in the rind and shed more water.
| Binding | Average DM loss | Lost from a 1,400 lb bale |
|---|---|---|
| Sisal twine | 19.5% | ~273 lb |
| Plastic twine | 11.3% | ~158 lb |
| Net wrap | 7.3% | ~102 lb |
Field experience tracks the research closely. One operator's side-by-side after a wet season: 30 inches of summer rain left his net-wrapped grass bales with less than 2 inches of spoilage on top, while twine-tied bales — and bales where the net had torn — had 12 inches of rot.
The mechanism is simple. Twine holds hay at the strings and leaves the surface between them open, so rain runs into the bale instead of off it. Net wrap creates a continuous shell that sheds water, which is also why net-wrapped bales shed less crop in transport and hold their shape in a stack.
Speed is the second lever. UGA's forage team cites Wisconsin work finding a net wrap baler can wrap up to 32% more bales than a twine baler, because the chamber makes far fewer revolutions per bale. The same piece puts the material premium at roughly $0.30–$0.50 per bale — which, set against 4 percentage points of dry matter, is the whole argument in one line. SDSU Extension's overview of binding choices reaches the same conclusion. The full cost breakdown is in net wrap vs twine.
If you have a twine-only round baler and have wondered whether it can be converted, it usually can: see adding net wrap to a twine baler.
Frequently asked questions
What do the numbers on a baler twine box mean?
The first number is length in feet per ball; the second is knot strength in pounds. So 9600-170 means 9,600 feet with a 170 lb knot strength. Because balls are sold by weight, more feet means thinner, weaker twine — the two figures always trade against each other.
What knot strength twine do I need for a small square baler?
Most standard small square balers run 130–170 lb knot strength, with 9600-170 the common default. Dense hay, heavy bales, or high-capacity machines usually call for 170–210 lb, often on a shorter 7,200 ft ball. Check the operator's manual before jumping a grade.
Is sisal or poly baler twine better?
Poly is cheaper, stronger per diameter, and unaffected by moisture. Sisal costs roughly twice as much but decomposes, which matters if twine ends up in a manure spreader, a field, or compost. Choose sisal when you can't retrieve the twine, poly for everything else.
Do I need new billhooks to run poly twine?
Usually not. Manufacturers do sell separate sisal and multi-twine billhooks, but most operators run poly on sisal-era hooks successfully after adjusting twine tension. If knots start missing, check for dull knotter knives first — that's the far more common cause than billhook type.
How long does solar-degradable baler twine last?
Roughly 90 days to a year of sun exposure, depending on climate. It's standard polypropylene made without UV inhibitor, so it degrades on stored bales as readily as on twine dropped in a field. Use it for hay fed within the season, not for carryover.
How much twine does a round bale use?
A 5×6 round bale with 15–20 wraps uses roughly 280–380 feet of twine, so a 20,000 ft ball covers about 50–70 bales. At typical poly pricing that's around 35–55 cents per bale — before accounting for the extra baling time twine wrapping adds versus net wrap.
The bottom line
Read the label as feet and knot strength, match the strength to the baler rather than the sale tag, and pick sisal or poly based on where the twine ends up rather than on price alone. If knots start missing after a twine change, sharpen the knives before you buy billhooks. And on a round baler, run the spoilage numbers honestly — the twine is cheaper per bale right up until the first wet season, when the difference lands in your feed budget instead of your input budget.
XES Extreme bale net wrap is built to hold edge-to-edge so bales shed water, keep their shape, and hold their feed value through storage and transport — shop factory-direct net wrap, or use the baler size checker to confirm the right width for your machine.
