The basic steps to reload your trimmer head

To replace the string on a Ryobi 40V cordless trimmer, you'll remove the spool from the trimmer head, wind new string onto it, and snap it back in place. The whole job takes about five minutes once you have the right string. You don't need tools—just your hands and a replacement spool or bulk string that matches your trimmer model.

Ryobi makes this easier than many brands because the spool design doesn't require you to thread string through a guide or tie knots. You straightforward load the string into two slots on the spool, wind it up, and the trimmer head holds it in place as you work.

Key Takeaways

  • Ryobi 40V trimmers use a bump-feed spool that you can reload yourself without special tools or informed.
  • You need string that matches your trimmer's diameter—usually 0.065 inches or 0.080 inches, printed on the spool or in your manual.
  • The spool twists off by hand; you don't need to remove the trimmer head itself.
  • Wind the string tightly and evenly into both slots, leaving 4 to 6 inches of string sticking out on each side for cutting.
  • If your spool is cracked or the slots are stripped, replace the entire spool rather than trying to repair it.

What string diameter your trimmer needs

Check the spool itself first—most Ryobi spools have the string diameter printed on the plastic. Common sizes are 0.065 inches and 0.080 inches. If you can't find it on the spool, look in your trimmer's manual or search the Ryobi website for your specific model number.

Using the wrong diameter will either jam in the head or feed too loosely and break constantly. Buy a spool of pre-wound string or bulk string in a roll—both work, but pre-wound spools are faster if you're not comfortable winding by hand. Bulk string costs less if you trim regularly.

How to remove and reload the spool

Unplug the trimmer or remove the battery. Locate the spool at the bottom of the trimmer head—it's the round plastic piece with two slots. Grip it firmly and twist counterclockwise by hand until it comes free. Some spools are tight; if yours won't budge, wrap a cloth around it for better grip.

Once the spool is off, look at the two slots running around the edge. One slot is usually slightly longer than the other. Insert the end of your new string into the longer slot and push it all the way to the bottom. Wind the string tightly and evenly around the spool, following the direction of the slot. Keep tension on the string as you wind so it doesn't bunch up.

When you reach the other slot, guide the string into it and continue winding in the same direction. The string should fill both slots without overlapping itself. Leave 4 to 6 inches of string hanging out on each side—this is what cuts the grass. Screw the spool back onto the trimmer head by twisting clockwise until it's snug. Don't over-tighten; hand-tight is enough.

Winding string if you're using bulk line

Bulk string comes in a large spool or coil. Cut a length of about 20 to 25 feet—this is usually enough to fill a trimmer spool twice. If you're not sure, unwind the old string and measure it before you throw it away.

Find the end of the bulk string and insert it into the longer slot on your empty spool. Wind it tightly and evenly, keeping the string flat and parallel to the previous wrap. If the string twists or bunches, stop, unwind a few turns, and start again. Tension matters more than speed. Once both slots are full and you have 4 to 6 inches hanging out on each side, you're ready to reinstall the spool.

When to replace the spool instead of reloading it

If the spool is cracked, melted, or the slots are stripped or damaged, reloading won't help—the string won't stay in place or will slip as you work. Buy a replacement spool for your trimmer model. Ryobi sells them separately, and they're inexpensive. straightforward twist off the old spool and twist on the new one, then load it with string as described above.

Spools can wear out from repeated winding and unwinding, especially if you trim frequently. If you notice the string slipping or the spool wobbling on the head, it's time for a new spool. This is a normal wear item, not a sign that your trimmer is failing.

How to test your reload before you trim

Before you start trimming, hold the trimmer head over a trash can and tap the bump knob on the bottom of the head against the ground a few times. This feeds out a little string so both sides are even. If the string doesn't feed out, or if it feeds unevenly, the spool may not be seated properly. Unscrew it, check that the string is in both slots, and try again.

Once the string feeds smoothly, you're ready to work. As you trim, the bump knob automatically feeds more string when you tap it on the ground. If the string stops feeding after a few bumps, the spool may be empty or the string may have slipped out of a slot. Remove the spool and reload it.

Frequently Asked Questions

Can I use any brand of string on my Ryobi trimmer?

Yes, as long as it matches the diameter your trimmer needs. Ryobi, Echo, Stihl, and generic bulk string all work if the thickness is right. The brand doesn't matter—only the diameter. Check your spool or manual to confirm whether you need 0.065 or 0.080 inches.

What if I wind the string the wrong direction?

The string will still stay in the spool, but it may not feed smoothly when you bump the knob. If this happens, unwind it and wind it again in the opposite direction. The slots are designed to work with the trimmer head's rotation, so direction does matter for smooth feeding.

How much string should stick out of the spool?

Leave 4 to 6 inches on each side. This gives the trimmer head room to feed the string out as you work. If you leave too much, it may tangle or jam. If you leave too little, the trimmer won't cut properly until you bump the knob several times.

Do I need to replace the spool every time I reload it?

No. A spool lasts for many reloads. Replace it only when it cracks, melts, or the slots become damaged and won't hold the string. Most people reload the same spool 10 to 20 times before it needs replacing.

What if the spool won't twist off?

Wrap a cloth or rubber grip around the spool for better traction and try again. If it's still stuck, let the trimmer sit for a few minutes—sometimes the plastic shrinks slightly when it cools. Never use pliers or force, as you can crack the spool or damage the threads on the trimmer head.