The fastest way to reload your trimmer

Most grass trimmers use one of two reload methods: automatic feed (bump the head on the ground and line advances) or manual wind. If your trimmer has a spool inside the head, you unscrew the cap, remove the old spool or wind new line onto it, and screw the cap back on. If it has a fixed bobbin, you wind line directly onto the bobbin, then thread the ends through the eyelets. Either way, the job takes about five minutes once you know which type you have.

The hardest part is usually getting the cap off without stripping it. Use a flat-head screwdriver that fits the slot snugly, or look for a notch on the side of the head — many caps have two notches designed for a coin or a special tool. Turn counterclockwise. If it will not budge, spray the seam with penetrating oil and wait ten minutes.

Key Takeaways

  • Check your trimmer manual or the head itself to find out whether you have a removable spool or a fixed bobbin, because the reload method is different for each.
  • Measure the line diameter (usually 0.080 or 0.095 inches) printed on the spool or in your manual before you buy new line, because the wrong size will not feed or will jam.
  • Wind line onto the spool in the direction the arrow on the spool points, and leave 4 to 6 inches of line sticking out on each side so the eyelets can catch it.
  • If the cap will not unscrew, use a coin in the notches on the side of the head rather than forcing a screwdriver into the slot.

Removable spool: the most common type

Open the trimmer head by unscrewing the cap. Most caps have a single slot for a flat-head screwdriver, or two notches on opposite sides where you can fit a coin. Once the cap is off, the spool will either come out freely or be held by a small clip or pin — if there is a pin, pull it straight out and set it aside.

Look at the spool. One side will have an arrow printed on it showing the direction to wind. The other side usually has a small hook or notch where the line end catches. Strip off any old line still wound on the spool. If the spool is cracked or the hook is broken, replace the spool itself — they cost $5 to $15 and are sold by trimmer brand.

Cut a length of new line. Most people wind the full length the spool will hold, which is usually 20 to 30 feet. Start at the hook or notch, and wind the line tightly in the direction the arrow points. Keep the line under tension as you wind so it does not bunch up. When you reach the end of the spool, tuck the line into the notch or hook on the opposite side to hold it in place.

Insert the spool back into the head. If there was a pin, push it back through the hole. Thread the two line ends through the eyelets (the small holes in the trimmer head where the line comes out). Leave 4 to 6 inches of line sticking out on each side. Screw the cap back on, turning clockwise until it is snug — do not over-tighten or you will strip the threads.

Fixed bobbin: less common, but simpler

Some trimmers have a bobbin (a spool-shaped post) that is permanently attached inside the head. You cannot remove it. Instead, you wind line directly onto the bobbin, then thread the ends out through the eyelets.

Open the head cap the same way — unscrew or use a coin in the notches. Look for an arrow on the bobbin showing which direction to wind. Strip off any old line. Starting at the base of the bobbin, wind new line tightly in the direction the arrow points, keeping tension on the line as you go. Wind until you reach the top of the bobbin or until the line feels snug and will not slip.

Thread one end of the line through one eyelet, and the other end through the opposite eyelet. Leave 4 to 6 inches sticking out on each side. Screw the cap back on. This design is less common because the line cannot be replaced as easily — if you wind it wrong, you have to unwind the whole thing and start over.

Choosing the right line size

Grass trimmer line comes in different diameters, most commonly 0.080 inches, 0.095 inches, and 0.105 inches. Using the wrong size will cause the trimmer to jam, skip, or fail to feed line at all. Check your trimmer manual or look at the spool itself — the diameter is usually printed on the side or bottom.

If you cannot find the size printed anywhere, measure the eyelet hole with a ruler or calipers. The line should fit snugly but not so tight that you have to force it through. When in doubt, buy a small spool of 0.080 inch line first — it is the most common size and works on most residential trimmers.

Line material is usually nylon, and all nylon line works the same way. Brands do not matter much. Buy from a hardware store, a big-box retailer, or online — a 100-foot spool costs $3 to $8 and will last most homeowners several months of regular use.

What to do if the line keeps breaking

If your trimmer breaks line every few minutes, the problem is usually one of three things: the line is the wrong diameter, the eyelets are cracked or sharp, or the spool is wound too loosely.

First, confirm you are using the correct line size for your trimmer. If you are, inspect the eyelets for cracks or rough edges. Run your fingernail across the inside of each eyelet — if you feel a burr or sharp spot, the eyelet is damaged and the line will fray and break there. You can smooth a minor burr with fine sandpaper, but if the eyelet is cracked, the head will need to be replaced.

If the eyelets are fine, rewind the spool. Loose winding is the most common cause of line breakage. Wind the line under firm tension so it sits flat and does not bunch up. Leave exactly 4 to 6 inches sticking out — too much line creates drag and causes breakage, and too little means the line will not reach the cutting zone.

Automatic feed versus manual wind

Automatic feed trimmers advance line by themselves when you tap the head on the ground. The line is wound on a spool inside the head, and a spring mechanism feeds it out a small amount each time you bump. These are convenient but can waste line if you bump too often.

Manual wind trimmers require you to stop, open the head, and manually advance the line by hand. This wastes less line but takes more time. The reload process is the same for both — the difference is only in how the line is fed during use, not how you load it.

If your automatic feed trimmer is not advancing line when you bump, the problem is usually a worn spring or a spool that is wound too loosely. Try rewinding the spool with firm tension first. If that does not work, the spring mechanism may need replacement, which usually means buying a new head assembly ($20 to $40).

Frequently Asked Questions

How do I know which direction to wind the line?

Look at the spool or bobbin for an arrow printed on the side. Wind in the direction the arrow points. If there is no arrow, wind counterclockwise when you are looking at the spool from above. When in doubt, wind a few feet, then try to pull the line — if it unwinds easily, you are winding the wrong way.

Can I use any brand of trimmer line?

Yes. All nylon trimmer line of the same diameter works the same way. Brand does not matter. Buy whatever is cheapest at your local hardware store, as long as the diameter matches your trimmer.

What if I wind the line the wrong way?

The trimmer will not feed line, or the line will unwind as soon as you start cutting. Stop, open the head, and rewind in the opposite direction. It takes only a few minutes to fix.

How much line should stick out of the eyelets?

Leave 4 to 6 inches on each side. Too much line creates drag and causes breakage. Too little means the line will not reach the grass. If you are not sure, start with 5 inches and adjust after your first use.

Do I need to replace the spool itself, or just the line?

Usually just the line. Spools last for years. Replace the spool only if it is cracked, the hook is broken, or the threads where the cap screws on are stripped.