Best Filament Dryer and Why the Humidity Readout Lies to You
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Switch a filament dryer on and the humidity number on the front drops within minutes. Nothing has dried. Relative humidity is measured against how much water air can hold at that temperature, and warming air raises that capacity, so the reading falls without a single molecule of water leaving the box. Actual drying needs three things: heat to drive moisture out of the plastic, airflow to carry it off the spool, and somewhere for that water to go. Seal a box with no vent and no desiccant and the chamber reaches equilibrium, at which point the filament stops giving up moisture and takes some back as it cools. So I score these on moisture removal rather than on the temperature they advertise.
Top picks
SUNLU S4 — Best overall
- 4 Spool Capacity: SUNLU 3D printer filament dryer S4 can dry up to four 1kg 3D printer filaments, enhancing drying efficiency and printing quality when drying while printing
- Large Dimensions: SUNLU filament dryer S4 is notably large in size with external dimensions of 460(L) * 220(W) * 310(H)mm, internal dimensions of 450(L) * 175(W) * 207(H)mm, and net weight of 4KG
- 8 Filament Exit Holes: SUNLU filament dryer S4 features eight filament outlets for multiple printers and various filament loading angles, ensuring smoother loading and printing
Why it wins: Three circulation fans across a four-spool chamber, which addresses the part of drying most boxes skip. Heat alone warms the outside of a spool and leaves the inner windings damp, and moving air is what reaches them. A 350W PTC element and a 70°C ceiling put it above the PLA-only crowd without going to engineering-filament prices.
Pros
- Three circulation fans rather than a single element and hope
- Four spools at once, so a print job and its spares dry together
- 70°C covers PLA, PETG, ABS and TPU
- 350W heats a full chamber rather than trickling
Cons
- Bulky next to a single-spool box
- 70°C is short of what nylon and polycarbonate really want
- Fans are audible in a quiet room
Social proof: See rating and reviews on Amazon.
Trade-offs and who should skip: Airflow is the feature and noise is the cost. Skip it if the dryer lives on a desk you work at. Skip it if you only ever print PLA, where a cheaper single-spool box does the same job.
Scores: Performance 5/5 | Moisture removal 5/5 | Ease of use 4/5 | Value 4/5
Creality Space Pi X4 — Best for engineering filaments
- Note: Please make sure that other brands' plastic trays are heat resistant, please use Creality high quality rfid filament with plastic trays.
- Creality Space Pi X4 Filament Dryer: Creality Filament Dryer 4 Spools revolutionizes filament drying with 4 spools dry and print at once for maximum efficiency. With eight filament holes and PTFE tubing, this innovative dryer meets the need for drying multiple filaments and allows printing on four printers at the same time
- Dual Chambers Independent Temperature Control: Creality Space Pi X4’s each chamber is equipped with an independent PTC heater, allowing simultaneous drying of two filament types at different temperatures in one machine
Why it wins: An 85°C ceiling with two independently heated chambers, which is the specification that matters if you print nylon, PC or PA. Those materials need higher drying temperatures than a 65°C box can reach, and running two chambers separately means a nylon spool at 80°C and a PETG spool at 55°C in the same machine.
Pros
- 85°C ceiling, the highest here alongside the Sovol
- Two chambers that run at different temperatures at once
- Handles PA, PC and ASA rather than stopping at PETG
- Strong owner rating for a premium unit
Cons
- The most expensive pick on this page
- 200W draw is significant if it runs for long sessions
- Overkill if PLA and PETG are your whole shelf
- Larger footprint than most benches have spare
Social proof: See rating and reviews on Amazon.
Trade-offs and who should skip: You are paying for headroom you may never use. Skip it if nylon is not in your future, because the extra 20°C buys nothing for PLA. Skip it if bench space is tight.
Scores: Performance 5/5 | Moisture removal 4/5 | Ease of use 4/5 | Value 3/5
Creality Space Pi Dryer Plus — Best for mixed materials
- 【Upgraded PTC 360° Hot-air Heating】The filament dryer quickly heats with a built-in fan, circulating hot air 360° for uniform heating, dryer box input voltage: 110V 50/60Hz, effectively drying moisture filaments and improving printing results
- 【Advanced PTC Heating Technology】Creality space pi filament dryer box plus employs a unique 110W PTC heater to warm up the space, a feature that sets us apart in the market. Unlike most filament dryers that use a Pl heating pad and often result in uneven drying, our model with the PTC heater ensures uniform drying. This PTC heater is not only durable and energy-saving,but also eco-friendly
- 【Easy Operation LCD Touch Screen】The Creality Space Pi Filament Dryer comes with a 3.7-inch touch screen for easy operation, making it simple for you to track drying conditions. The touch screen supports switching between ℃ and ℉ temperatures more convenient settings
Why it wins: Twelve material presets across a 45°C to 70°C range, which removes the guesswork that ruins spools. Drying temperature is not a dial you should eyeball: too low and the moisture never leaves, too high and the spool softens and the windings weld together. Having the manufacturer pick the number per material is worth more than another ten degrees of ceiling.
Pros
- Twelve presets, so temperature is chosen rather than guessed
- Two spools with 360° hot air circulation
- Real-time humidity monitoring on the display
Cons
- 70°C stops short of what nylon and polycarbonate want
- Presets are a starting point, not a guarantee for third-party filament
- The humidity display drops on heating, so read it as a trend rather than proof
- Costs more than a single-spool box for one extra spool
Social proof: See rating and reviews on Amazon.
Trade-offs and who should skip: Convenience and headroom pull against each other, and this picks convenience. Skip it if you print engineering materials, where the X4 is the right tool. Skip it if you already know your temperatures and would rather buy capacity.
Scores: Performance 4/5 | Moisture removal 4/5 | Ease of use 5/5 | Value 4/5
Comgrow Filament Dryer Box — Best value
- Large Storage Volume -Filament Dry Box Inner Size: 9.29*6.49*9.13 inch. Comgrow dryer box can store 2 rolls of 1kg spools, compatible with PLA ABS SILK filament. Works perfectly with all standard filament diameters 1.75mm/2.85mm.
- Setting Notes - Set the temperature and duration after turning on the filament dehydrator. The machine will work only when the work state is displayed on the screen. If the work mode is not displayed, the motherboard will automatically shut down after 3 minutes. If you have any unsolvable problems with the COMGROW filament dryer box, please feel free to contact us, our after-sales technical team will provide you with detailed solutions within 24 hours.
- Filament Dryer and Remove Moisture - Comgrow 3d printer filament dryer box is designed to keep filament dry and remove moisture from kinds of filaments. Internal heating during printing provides a dry storage environment for 3D printer filaments and keeps the filament dry. Avoid entanglement, clogging, poor adhesion, and layer migration caused by the dampness of the printing wire. (Note: Only used for the drying of 3D printer Filament)
Why it wins: By far the largest review base in this category, at roughly a third of what the four-spool units cost. It holds one spool, heats it, and doubles as the holder you feed from, which covers the ordinary case of a PLA or PETG spool that has been open too long.
Pros
- Thousands of owner reviews, the most here
- Feeds directly into the printer while drying
- Cheap enough to buy two
Cons
- One spool at a time
- Lower ceiling than the engineering-grade boxes
- No independent temperature zones
Social proof: See rating and reviews on Amazon.
Trade-offs and who should skip: This is the sensible default and it does one spool. Skip it if you print nylon. Skip it if you burn through several materials a week, where reloading gets tedious.
Scores: Performance 4/5 | Moisture removal 3/5 | Ease of use 5/5 | Value 5/5
Polymaker PolyDryer — Best for printing straight from the box
- CONSISTENT DRYING PERFORMANCE - Designed to help keep filament in better condition for printing, Polymaker filament dryer supports more stable print results by helping reduce moisture-related issues such as stringing, bubbling, clogging, and layer inconsistency. The drying dock promotes even airflow and controlled heating, helping your filament stay better prepared before and during use.
- DRY, STORE, AND PRINT WITHOUT BREAKING SEAL - Built as a connected drying and storage solution, this 3D filament dryer lets you move from drying to sealed storage and direct filament feeding with less exposure to ambient moisture. This helps lock in dry conditions between prints while keeping filament ready to use when your next job starts.
- HUMIDITY CONTROL & MONITORING - With a storage-box-based protection setup, our Polydryer makes it easier to monitor, track, and maintain dry conditions for your filament. A built-in hygrometer helps you judge filament status with less guesswork and supports better day-to-day management between print sessions.
Why it wins: It dries, stores and feeds without breaking the seal, which matters because the drying is the easy part and keeping filament dry afterwards is where most setups fail. A spool dried perfectly and then left on an open holder is back to ambient moisture within days.
Pros
- Dry, store and print without opening the chamber
- Modular, so storage boxes can be added
- Addresses re-absorption rather than only drying
Cons
- Costs more than a plain single-spool dryer
- The modular approach only pays off if you buy into the system
Social proof: See rating and reviews on Amazon.
Trade-offs and who should skip: You are buying a workflow rather than an appliance. Skip it if you dry occasionally and store in vacuum bags, which is cheaper and works. Skip it if you would not commit to one brand’s ecosystem.
Scores: Performance 4/5 | Moisture removal 4/5 | Ease of use 5/5 | Value 4/5
Quick compare
- Best overall: SUNLU S4, three fans and four spools, audible
- For nylon and PC: Creality Space Pi X4, 85°C and two independent chambers
- Best for mixed materials: Creality Space Pi Dryer Plus, twelve presets, 70°C ceiling
- Best value: Comgrow dryer box, one spool, the most owner reviews here
- Best for staying dry: Polymaker PolyDryer, sealed from drying through to printing
A note on the readout: if you want to know whether a dryer is working, watch whether the humidity climbs back up after the heat cycles off. Air that has genuinely lost its water stays dry as it cools.
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