The fastest way to reload your strimmer

Most strimmers use one of three reload systems: twist-and-pull, bump-feed, or spool-based. The method depends on your machine's head design, not the brand. You remove the old line, wind new line onto the spool or into the chamber, and reassemble — the whole job takes under five minutes once you know which system you have.

The first step is always the same: stop the engine, let it cool, and disconnect the spark plug wire so the strimmer cannot start while you work. Then look at the head. If it has a single rotating knob on top, you have a twist-and-pull head. If it has a bump button underneath, you have bump-feed. If the entire head unscrews as one piece, you have a spool-based system. Each loads differently.

Key Takeaways

  • Identify your head type — twist-and-pull (knob on top), bump-feed (button underneath), or spool-based (whole head unscrews) — because each loads line in a different way.
  • Always disconnect the spark plug wire before opening the head, and use the correct line diameter for your machine, usually 2.0 mm or 2.4 mm.
  • Twist-and-pull heads need line wound tightly in one direction; bump-feed heads need line fed into a chamber in a specific pattern; spool-based heads need line wound onto a removable spool.
  • Wind line under tension so it sits flat and does not bunch, or it will jam when you try to feed it out.

Twist-and-pull heads: the most common design

Turn the knob on top of the head counterclockwise until it stops — do not force it. The knob will come free, and the spool inside will lift out. You will see two chambers, one on each side, with old line still wound in them. Pull out all the old line and discard it.

Cut a length of new line, usually 6 to 8 metres depending on your machine's manual. Feed one end into the left chamber, starting at the outer edge and winding it tightly toward the centre. Keep tension on the line as you wind so it does not bunch. When you reach the centre, tuck the end into the small notch or hook provided — this holds it in place while you load the right chamber.

Repeat the same process on the right chamber with a second length of line. Both chambers should be full and tight. Insert the spool back into the head, align the knob, and turn it clockwise until it clicks. Pull both line ends outward — they should feed out smoothly. If they jam, the line is bunched; unwind, re-tension, and try again.

Bump-feed heads: automatic line advance

Unscrew the plastic cap on the underside of the head — usually by hand, sometimes with a coin. The spool will drop out. Remove all old line and discard it. Look inside the chamber for a small post or peg; this is the anchor point.

Cut a single length of line, usually 5 to 7 metres. Tie a small knot at one end and hook it over the anchor post. Wind the line tightly around the spool in the direction marked by an arrow on the spool itself — this matters, because winding the wrong way will prevent the bump mechanism from feeding line out. Keep the line under tension as you wind so it lies flat and does not overlap itself.

When the spool is full, feed the free end of the line through the exit hole in the chamber wall. Reinsert the spool, screw the cap back on, and pull both line ends outward to seat them in the guides. The line should feed out smoothly when you tap the bump button on the ground.

Spool-based heads: the removable cartridge

Unscrew the entire head from the shaft — usually by hand, sometimes with a wrench depending on the model. The head will separate into two halves, and the spool will be visible inside. Remove the spool and any remaining old line.

Cut a length of new line, usually 6 to 8 metres. Tie a knot at one end and hook it into the anchor slot on the spool. Wind the line tightly in the direction marked on the spool, keeping it under tension so it does not bunch or overlap. Fill the spool until the line is level with the rim.

Feed the free end through the exit hole in the head housing. Reassemble the two halves of the head, making sure the line ends are seated in the guides on both sides. Screw the head back onto the shaft and tighten by hand until snug — do not over-tighten, or you will crack the plastic.

Choosing the right line diameter and material

Strimmer line comes in different thicknesses, and using the wrong one will cause jamming or poor cutting. Check your machine's manual or look for a marking on the head itself — most domestic strimmers use 2.0 mm or 2.4 mm diameter. Commercial machines sometimes use 3.0 mm or thicker. Buy the exact size your machine specifies.

Line material varies too. Standard nylon is cheapest and works for grass and light weeds. Twisted or serrated nylon cuts thicker growth better but wears faster. Some machines accept only one type, so check the manual before buying in bulk. A 15-metre spool costs between £3 and £8 depending on material and brand; buying a larger spool is usually cheaper per metre if you use the strimmer regularly.

What to do if the line jams or will not feed

If the line jams when you try to feed it out, the spool is wound too loosely or the line is bunched. Remove the head, unwind the spool completely, and start again. This time, keep firm tension on the line as you wind — pull it taut with your other hand so it sits flat and does not overlap.

If the line feeds out but catches or breaks when ready, the exit guides may be cracked or blocked. Look inside the head for debris or damage. Clean out any grass or dirt with a small brush or compressed air. If a guide is cracked, the head will need to be replaced — they are not usually repairable.

If one side of the head feeds line but the other does not, check that both line ends are seated properly in their guides. Sometimes one end pulls free during reassembly. Remove the head, reseat both lines, and reassemble.

How often to replace strimmer line

Line wears down with use and will eventually become too short to cut effectively. How often you reload depends on how much you use the strimmer and what you cut. Light weekly use on grass might need a reload every 4 to 6 weeks. Heavy use on thick weeds or rough ground might need a reload every 2 to 3 weeks. When you notice the cutting width shrinking or the line breaking frequently, it is time to reload.

Keep a spare spool or two of the correct line diameter in your shed so you are not caught without when you need to use the strimmer. Storing line in a cool, dry place keeps it from becoming brittle — nylon degrades in sunlight and heat.

Frequently Asked Questions

Can I use a different line diameter than the manual says?

No. Using thicker line than your machine is rated for will jam the feed mechanism and can damage the head. Using thinner line will not cut effectively and may break constantly. Always match the diameter specified in your manual or marked on the head.

What if I wind the line the wrong direction on a bump-feed spool?

The bump mechanism will not feed line out, and you will waste time tapping the button on the ground with nothing happening. Unwind the spool completely and wind it again in the direction marked by the arrow. The arrow is there for a reason.

How tight should I wind the line?

Wind it under firm tension so it lies flat and does not bunch or overlap itself. If you can see gaps between the coils or the line is loose enough to move when you press it, it is too loose. Rewind it tighter. If the spool is so full that the line bulges out of the chamber, you have wound too much — remove some and try again.

Can I use old line I found in the garage?

Only if you know its diameter and it matches your machine's specification. Old nylon line can become brittle and break more easily, especially if it has been stored in sunlight or heat. New line costs little and breaks less often, so it is worth buying fresh.

Do I need to clean the head before reloading?

Yes, if there is grass, dirt, or debris inside. Use a small brush or compressed air to clear the chamber and guides. Debris can jam the new line or prevent it from feeding smoothly. Take 30 seconds to clean before you reload.