Dewalt 20V Weed Eater String Size — Which Line Should You Use?
If you own a Dewalt 20V string trimmer and have ever stood in the yard wondering which replacement line to buy, you’re not alone. I’ve mowed around flowerbeds and wrestled with stubborn crabgrass long enough to learn that the right string makes a huge difference in cut quality, run time, and frustration level. In most Dewalt 20V trimmers the safest, most common line size is 0.080 inch (about 2.0 mm), but there are a few exceptions and important details to check first.
How to confirm the correct line size for your Dewalt 20V model
Before anything else, find your model number (it’s usually on the motor housing or in the user manual) and check the owner’s manual or the label on the trimmer head. If you don’t have the manual handy, look at the spool or the head — many Dewalt heads are stamped with the recommended line diameter. If that fails, measure the old line with a caliper or a ruler. When in doubt, use 0.080 inch unless the manual explicitly calls for a different diameter.
Common sizes and when they’re used
- 0.080 inch (2.0 mm) — This is the most common line size for Dewalt 20V battery trimmers. It balances cut power with battery life and fits most standard bump-feed and fixed-head spools.
- 0.095 inch (2.4 mm) — Some heavier-duty heads and certain Dewalt models will accept thicker line for tougher weeds. Only use this if the manual or head label lists 0.095 as acceptable.
- 0.065 inch (1.7 mm) — Occasionally used on very lightweight consumer trimmers to extend run time, but it’s less common on Dewalt 20V models and won’t hold up well on thick weeds.
Line shape matters too — not just diameter
String comes in round, twisted (or spiral), and squared-off profiles. In my experience, round line is the most forgiving and easy to spool, so it’s great for everyday lawn edging and trimming. Twisted or serrated lines can give a cleaner cut on tougher weeds and dewy grass but might wear the head slightly faster. Many Dewalt users stick with round 0.080 line for the best balance of performance and convenience.
How to replace the line on a Dewalt 20V trimmer
Spooling line correctly is half the battle. Here’s my go-to method that has saved me time and headaches:
- Turn the battery out of the trimmer for safety.
- Remove the spool cap — usually a few tabs or a twist-and-lock action.
- Take out the old line and clean debris from the spool and head.
- Cut two lengths of 0.080 line following the manual’s recommended length (typically 10–20 feet per side for dual-line heads; check your model).
- Insert the line ends into the anchor holes and wind neatly in the direction indicated on the spool. Keep the wraps tight and even.
- Feed the line through the eyelets on the spool housing and replace the cap securely.
- Test bump and feed to make sure the line advances and that there’s no binding.
Troubleshooting: My trimmer won’t feed or the line keeps breaking
Here’s what I check first when the Dewalt 20V trimmer misbehaves:
- Line diameter mismatch — If the line is too thick for the head it won’t feed right. Swap to 0.080 if you had thicker line and the head won’t spin freely.
- Poor winding — If the line is tangled or wound lightly, it may bind. Rewind it neatly with even tension.
- Worn head parts — Inspect the bump cap, springs, and eyelets. Replace if cracked or deformed.
- Wrong line type — Some heads don’t like rigid square line; use round or the shape recommended by Dewalt.
“I once tried a very abrasive, twisted 0.095 line on my 20V trimmer to handle tall foxtail; it cut like a champ but killed the bump-feed rubber in a season. I went back to 0.080 round for everyday use and keep the thicker line for occasional heavy work when I have a compatible head.”
Will thicker line drain the battery faster?
Yes. Thicker, heavier line requires more torque to spin and will make the trimmer work harder, which shortens run time per battery charge. That’s another reason to stick with 0.080 on battery-powered Dewalt models unless you truly need a heavier cut for short bursts.
Best practices and products I recommend
- Stick with 0.080 inch round line for general trimming with Dewalt 20V trimmers unless the manual states otherwise.
- Buy quality line from reputable brands or Dewalt’s OEM line to avoid brittle or misshapen string.
- Keep a spare pre-wound spool or a roll of 0.080 line on hand — swapping a spool is a lot faster than winding in the yard.
- Store line in a cool, dry place; heat can warp thin lines and cause feeding issues.
Final thoughts from a backyard gardener
I love a good, tidy edge and a trimmer that just works. In my yard, 0.080 inch round line for the Dewalt 20V trimmer has been the sweet spot: reliable, easy to spool, and forgiving when I run it through clippings and occasional lawn debris. When I need extra bite I’ll switch to thicker line for a job, but I always confirm fit first. Treat your trimmer head kindly, follow the manual, and you’ll avoid a lot of mid-season fuss.
If you tell me your specific Dewalt 20V model number I can look up the exact recommended line size for your head and even walk you through a step-by-step spool replacement for that model. Happy trimming!
