How to Choose a Filament Dryer: The Specs That Matter

Who this guide is for

This guide is for anyone who has decided they need a heated dryer and wants to know which specs to compare. If you're still deciding between a dryer and a sealed box, start with our filament dryer vs dry box guide. If you want a shortlist of specific dryers, go to the filament dryer shortlist. This page explains what each spec means, what dryer makers and filament makers publish, and where their own figures don't line up. We haven't tested any dryer for this page.

We refer to ten dryers we've verified: the SUNLU FilaDryer S2, S4, E2 and SP2, the Creality SpacePi X4, the Polymaker PolyDryer, the eSUN eBOX Lite, the EIBOS Cyclopes and Easdry, and the Sovol SH02. For side-by-side detail on these, see our comparisons:

• SUNLU FilaDryer E2 vs S2
• SUNLU FilaDryer S4 vs Creality SpacePi X4
• SUNLU FilaDryer S2 vs Polymaker PolyDryer
• eSUN eBOX Lite vs SUNLU FilaDryer S2
• EIBOS Cyclopes vs Sovol SH02

Step 1: Find the drying temperature your filament needs

Prusa's drying article puts the order plainly: "Make sure to check the specifications of the box you intend to use to make sure that it matches the drying temperature of your filament." So the filament comes first, and the filament makers' numbers differ. Here's what six makers publish for their own filaments:

Sources: Bambu Lab's drying wiki (forced-air oven column), Prusa's drying article, Polymaker's product wiki pages, Overture's drying guide, eSUN's drying-temperatures FAQ (temperatures only, no times) and its TPU-95A product page, and ELEGOO's product pages. eSUN's TPU-95A page gives two figures: 55 °C for more than 4 hours in its printing recommendation, and 60 °C for more than 8 hours in its notes. The ELEGOO "±" figures come from each product page's specifications table, and the PETG PRO figure from its description. "Not found" means we didn't find a figure on the maker pages we checked.

What the table shows:

• PLA, PETG and TPU stay at 70 °C or below for every maker listed, though ELEGOO gives its TPU figure as 70 ± 5 °C.
• ABS, ASA and PC run from about 70 °C (Polymaker's ABS and ASA) to 85 °C (Prusa's PC Blend and the top of Bambu's range).
• Nylon varies most, from eSUN's 70–80 °C to Polymaker's 100 °C for PolyMide CoPA.

Bambu Lab also gives different settings for drying on a printer's heated bed and in its AMS units, so even one maker has several right answers depending on the equipment. Prusa attaches two warnings to its own settings: "It is important not to exceed these temperatures while drying the filament, or the filament will soften and stick together," and "stick to the recommended drying times to prevent overdrying."

Step 2: Is the dryer hot enough for your filament?

Once you know the hottest setting you'll need, compare it with what each dryer maker publishes:

• 65 °C: EIBOS Easdry (40–65 °C, which EIBOS says is based on a 25 °C room).
• 70 °C: SUNLU FilaDryer S2 (35–70 °C), SP2 (35–70 °C), S4 (SUNLU says it heats up to 70 °C), and Sovol SH02 (40–70 °C).
• About 70 °C, with no set temperature: Polymaker PolyDryer. It uses three power levels, and Polymaker's FAQ says, "The highest range though is 68-73°C."
• 70 °C, with a conflicting spec row: EIBOS Cyclopes. Its user manual gives a "≤70℃" control range and a "0℃ to 70℃" setting range, and its data sheet says "Control Range: ≤ 70℃," but its tech specs say "≤80°C."
• 85 °C: Creality SpacePi X4 (45–85 °C).
• 110 °C: SUNLU FilaDryer E2 (35–110 °C).
• Not stated: eSUN eBOX Lite. eSUN's product page gives no temperature.

Compare those figures with the table. A 70 °C dryer reaches every maker's PLA, PETG and TPU setting (the midpoint of ELEGOO's 70 ± 5 °C for TPU), and only the lower ABS and ASA figures (Polymaker's 70 °C, ELEGOO's 70 ± 5 °C, and the bottom of eSUN's 70–80 °C range). The X4's 85 °C reaches every ABS, ASA and PC figure in the table, but not Prusa's, Overture's or Polymaker's nylon settings. Only the E2 reaches all of them.

When the material list and the temperature disagree

Several dryer makers list materials whose drying temperature, by filament makers' figures, is higher than the dryer's own maximum:

• SUNLU's wiki says the 70 °C S2 is "suitable for specialty filaments such as PA and PC," and says the S4 "heats up to 70°C for fast drying of specialty filaments such as PA and PC." SUNLU's own comparison blog lists the S2 as "Not suitable for high-temp engineering filaments."
• Sovol's SH02 has presets for nine materials, including PC and PA, with a 70 °C maximum.
• EIBOS lists nylon, PA and PC among filaments the 65 °C Easdry works with.
• Polymaker's PolyDryer manual lists PA and PC as supported materials, while Polymaker's own wiki gives 100 °C for PolyMide CoPA and 75 °C for PolyLite PC.

Creality is the only maker here that addresses the gap directly. Its X4 FAQ says filaments needing up to 85 °C "can be dried efficiently" and that "Those needing higher temperatures can still be dried, but with longer drying times." It also says, "For best results, follow the drying temperature recommended by the filament manufacturer." The other makers don't say how a lower temperature affects drying time, so we don't assume anything about it.

Step 3: Check spool fit and capacity

Capacity claims like "holds two 1 kg spools" depend on the spool, so measure the outer diameter and width of the spools you actually use. Here's what each maker states:

• Narrowest: EIBOS says the Easdry takes a spool smaller than Φ220 × 72 mm with a hub larger than Φ50 mm. Polymaker's manual limits the PolyDryer box to Φ205 × 78 mm, filament with spool, and its wiki says the standard box takes spools up to 1 kg.
• Single wide spools: SUNLU's wiki gives the S2 a maximum of φ210 × 85 mm.
• Two narrow spools or one wide one: EIBOS gives the Cyclopes two reels up to ф217 × 80 mm or one up to ф217 × 174 mm, though its "Max Spool Size" row says 170 mm. EIBOS says expansion parts take it to ф250 × 170 mm.
• Larger spools: Creality gives the X4 a limit of 200 mm diameter and 150 mm width, for 1 kg or 2 kg spools. SUNLU gives the E2 and SP2 a maximum of Φ250 × 153 mm. For the E2, SUNLU notes that "the test spools are SUNLU spools, other brands of spools will have slight differences."
• Not stated: SUNLU gives the S4's chamber as 450 × 210 × 211 mm for four 1 kg spools, but no maximum spool size. eSUN says the eBOX Lite takes 0.5 kg and 1 kg spools, with no dimensions. Sovol's SH02 page text gives no spool size.

For reference, Bambu Lab's wiki lists its reusable spool at 200 mm outer diameter and 67 mm high. Those two figures are within every stated diameter and width limit above, but a wider spool from another brand might not be.

Step 4: Can your spools take the drying heat?

A dryer's maximum doesn't matter if the spool deforms first. Here's what makers publish about spools:

• Bambu Lab sells its reusable spool in two types. Its store's specification table lists the Low Temp spool as ABS, rated "≤70℃," for PLA and PETG. The High Temp spool is ABS+PC, rated "≤90℃," for PLA, PETG, ABS, ASA, PA6-GF, ABS-GF, PAHT-CF, PET-CF, PA6-CF, PC and TPU. Bambu's drying wiki also warns that "Some third-party spools may not be heat-resistant enough and could deform during drying," and says to move spool-less refills onto a reusable spool before drying.
• Prusa says the black spool it introduced in October 2025 "resists drying temperatures as high as 90 °C," and its grey spool for Prusament PEI 1010 is "usable for temperatures reaching 150 °C." Its older black spools can be heated safely only to 45 °C without extra preparation, and the glue on its older grey spools withstands up to 90 °C.
• SUNLU's E2 FAQ says that "if the machine is set to operate at ≥70°C, the temperature resistance of the spool of the filament you are using should be ≥70°C to avoid deformation of the spool." Its SP2 FAQ gives the same example.
• Creality's X4 manual says, "The heat resistance temperature of the filament spool must exceed the set drying temperature; otherwise, there is a risk of heat deformation."

Put the two limits together. Bambu's own oven setting for ABS and ASA, 75–85 °C, is above its Low Temp spool's 70 °C rating, and Bambu lists ABS and ASA only under the High Temp spool. If a spool's maker publishes no rating, ask them before running a dryer above 70 °C.

Step 5: Compare heater power, with care

Makers publish heater power in different ways, so the figures aren't directly comparable:

• Maximum working power: S2 48 W (SUNLU wiki), PolyDryer 68 W (Polymaker manual), SP2 250 W (SUNLU store spec table).
• Rated power: Easdry 45 W (EIBOS data sheet), Cyclopes 100 W, S4 300 W (wiki) or 320 W (store), E2 325 W (wiki), X4 360 W.
• Heater element: SH02 150 W PTC, SP2 200 W PTC (store description), S4 300 W, 330 W or 350 W PTC depending on the SUNLU page, E2 500 W PTC (store page), and X4 two 200 W PTC heaters, one per chamber.

Only some makers publish heat-up times: the E2 reaches 50 °C in 20 minutes and 70 °C in 30 minutes from room temperature (SUNLU store), the SP2 reaches 70 °C in 15 minutes (SUNLU wiki), the SH02 reaches 50 °C in 7 minutes and 70 °C in 25 minutes (Sovol), and the S4 reaches 50 °C in 30 minutes (SUNLU store) and 70 °C in about 50 minutes (SUNLU blog). These are the makers' own figures under their own conditions. Creality is the only maker here that publishes energy use: 0.124 kWh in single-chamber mode and 0.208 kWh in dual-chamber mode for one hour at 85 °C.

Step 6: Look at airflow and how moisture leaves the box

Polymaker's wet filament page says dryers "combine heat and airflow to drive out moisture," and, about ovens, that "Airflow is important for efficient drying; without good air movement, it may take longer or require higher temperatures." Makers describe moisture removal differently:

• Fans that circulate heat. SUNLU says the S4's side and bottom fans keep the chamber within ±3 °C. EIBOS describes a built-in fan in the Cyclopes and Easdry, eSUN a "low-noise turbo fan" in the eBOX Lite, and Polymaker "360° airflow" in the PolyDryer.
• Vents and outlets. SUNLU says the S4's eight filament holes help because "the design effectively expels interior humidity." Creality says the X4's "Dual dehumidifying fans actively expel moisture during drying," and that its desiccant chamber connects to the heating airflow and regenerates with each use.
• What you do during drying. SUNLU's E2 FAQ recommends opening the silicone plug on the filament outlet during drying "to let the internal moisture fully discharged," then plugging it tightly afterwards, and keeping the top cover closed while it runs.

Step 7: Humidity readout, timer and controls

Humidity readout

Many dryers show humidity, but the readouts have limits:

• SUNLU lists the E2's display range as 10–90%, accurate to ±10%. At 80 °C or more, its sensor enters a protection mode and shows under 10%, and SUNLU says it takes about 20 hours to recover its accuracy after the temperature falls to 70 °C.
• Polymaker says the PolyDryer's hygrometer won't display lower than 10%. Polymaker's own test gave final readings of 20–30% at power level 1, 15–25% at level 2, and 10–20% at level 3, and it calls these "for reference only."
• EIBOS lists 10–99% for the Easdry and the Cyclopes, and SUNLU lists 10–90% for the SP2's hygrometer.
• The SUNLU S4 uses humidity to control itself: SUNLU says it starts drying when humidity reaches a set value between 30% and 50% and stops at 25%.

For a target, Bambu Lab says most filaments only stay dry for a while below 20% RH, and that a hygrometer can be used to monitor the actual humidity in a sealed container.

Timer

Published ranges: E2 and SP2 0–99 hours (SUNLU store), SH02 98 hours (Sovol), X4 1–48 hours (Creality), Cyclopes 1 minute to 24 hours or unlimited (EIBOS), S4 up to 99 hours (SUNLU user guide), and PolyDryer up to 24 hours in Regular Mode, with a Continuous Mode that runs until you stop it (Polymaker manual). SUNLU doesn't state a range for the S2, EIBOS doesn't for the Easdry, and eSUN doesn't for the eBOX Lite. Filament makers' times in the table above run from 4 to 12 hours, so any of the published ranges covers a single cycle.

Presets

SUNLU (S2, E2), Sovol (SH02, nine materials), and Creality (X4, "Drying Recommendations" and "My Drying" pages) all describe material presets. A preset is the dryer maker's setting, not your filament maker's, so check it against your spool's data sheet.

Step 8: Can you print while the filament dries?

Most of these makers say you can print from the box, but they describe it differently:

• SUNLU's S2 store page says it "Allows you to print while drying," and SUNLU's blog says all three of its S2, S4 and E2 models "support PTFE tube feed-through for active drying during printing." SUNLU says the S4 can feed up to four printers.
• Creality takes a more cautious line for the X4: "We recommend drying the filament thoroughly before printing," and "Once dried, you can feed the filament to your printer using a 4mm PTFE tube." Creality notes that the PTFE tube isn't included.
• Polymaker says the PolyDryer lets you "print directly from a dry environment," and its wiki says of the box, "You'll never have to break the seal again."
• eSUN says the eBOX Lite "only has the function of maintaining constant temperature and humidity during printing."
• EIBOS says filament can be used while it's in the Easdry or Cyclopes.

Bambu Lab's AMS units show one reason makers handle this carefully. Bambu says the AMS lowers its drying temperature once a print starts, usually below the filament's softening point, to prevent clogging in the AMS (45 °C for PLA, 55 °C for PETG). That's Bambu's rule for its own units. None of the dryer makers above publishes a printer or feeder they've tested with, so check the filament path on your own setup.

Step 9: Annealing, if you need it

Of the dryers here, only the SUNLU E2 is sold as an annealing box. SUNLU says it provides "80–90°C annealing for 2–3 hours." Its FAQ also says to use "the filament manufacturer's recommended temperatures and times for annealing" rather than the manual's reference figures. Filament makers' annealing settings vary. Polymaker, for example, says to anneal PolyMax PC "with your oven at 90˚C for 2 hours." Our annealing guide compares what filament makers publish.

Step 10: Safety features and instructions

Here's what each maker lists. None of these features makes a dryer safe to ignore:

• SUNLU E2: a two-level temperature control switch that cuts power on over-temperature and restores it on cooling, and an alarm "if the temperature exceeds the preset value by 10°C or the machine continues to work improperly." It also has double-layer insulation and "fireproof grade materials."
• SUNLU S4 and SP2: triple protection. For the S4, SUNLU lists a PTC thermistor, a temperature switch and software, with alarm prompts. For the SP2, it lists the PTC heater, a secondary temperature protection switch and software.
• Creality X4: drying pauses if fan speed is abnormal, a self-resetting PTC fuse cuts out at high temperature, and an NTC sensor at the air outlet pauses drying if the temperature is abnormal. Creality lists the housing as UL 94 V-0.
• Sovol SH02: a PTC thermistor that "automatically disconnects heating when the temperature exceeds 130°C, resuming once it falls below 90°C." Sovol's page text also lists exhaust temperature, fan rotation and mainboard temperature monitoring.
• Polymaker PolyDryer: error codes for a failed fan (E001) and for high temperature, where the board "automatically shuts down to protect the board" (E003).
• EIBOS and eSUN: the Cyclopes and Easdry pages don't list overheat protection. eSUN describes flame-retardant, heat-insulating foam inside the eBOX Lite.

The instructions matter as much as the features. Polymaker's manual says, "When unattended, please turn off the power supply to prevent accidental fire," and "DO NOT leave the dryer unattended when switched to Continuous Mode." It also warns that a loose filament end can block the heating vent, a "Risk of fire or damage." SUNLU's E2 safety notes say to turn off the power when not in use, not to block the air inlet and outlet, and not to place the dryer on anything heat-sensitive. SUNLU also warns that the E2's outer surface reaches 55 °C or more at settings of 80 °C and above. Creality's manual says to disconnect power if the X4 won't be used for an extended period.

Where makers' own figures conflict

Several makers publish two figures for the same spec. Where that happens, we give both rather than pick one:

• SUNLU E2: "500W PTC" on the store page and 325 W rated power in the wiki. Two capacities: two 1 kg, two 2 kg or one 3 kg spool (store), or two 1 kg or one 2 kg spool (wiki). Three statements about outside temperature: under 60 °C when the inside is above 100 °C (store), 60 °C or less "at 110°C operation" (wiki), and 55 °C or more at settings of 80 °C and above (store FAQ).
• SUNLU S4: a "Built-in 300W PTC heater" and "a heating power of 330W" on the store page, a "350W PTC heater" in the wiki, and rated power of 320 W (store) or 300 W (wiki).
• SUNLU SP2: "200W PTC + fan heating" in the store description, 250 W maximum working power in the store spec table, and 250 W rated power in the wiki.
• SUNLU S2: "suitable for specialty filaments such as PA and PC" (wiki), against "Not suitable for high-temp engineering filaments" (SUNLU blog).
• EIBOS Cyclopes: "≤80°C" in the tech specs, and "≤70℃" in the user manual, "≤ 70℃" in the data sheet and "up to 70 degrees" in the description.
• EIBOS Easdry: 45 W rated power in the data sheet and 55 W maximum power in the tech specs table. Its spec tables list 1.75 mm filament only, while its description lists 1.75, 2.85 and 3.00 mm.
• Creality X4: 60 °C for PETG on the product page and 65 °C in the user manual.
• eSUN eBOX Lite: its product page says the heating structure "ensures highly effective and stable drying performance," while its FAQ on the same page says "It is not suitable to promote the drying function."

For more on how these conflicts affect specific pairs, see the comparisons linked at the top of this page.

Checklist before you buy

• I know the drying temperature and time for each filament I use, from the filament maker's own page or data sheet.
• The dryer's published maximum reaches the hottest of those settings, or I accept the dryer maker's statement about lower temperatures.
• My spools' outer diameter and width are within the dryer maker's stated maximum, and I've allowed for the maker's note about other brands' spools.
• My spools are rated for the temperature I'll set, according to the spool's maker.
• I know how the dryer lets moisture out, and whether the maker says to open a plug or vent during drying.
• If I rely on the humidity readout, I know its range and any limits at high temperature.
• The timer covers my longest cycle, or the dryer has a continuous mode whose attended-use rules I'll follow.
• If I'll print from the dryer, I've checked the outlet, the PTFE tube size and whether a tube is included.
• If I want to anneal parts, the dryer is documented for it and reaches my filament maker's annealing temperature.
• I've read the safety instructions, including any rule about switching off when unattended.

When not to buy a dryer

• Your prints look fine. A sealed box with desiccant may be enough. See our filament storage guide and our silica gel guide.
• You aren't sure moisture is the cause. Work through how to tell if your filament is wet and stringing first. For material-specific symptoms, see our PLA problems and PETG problems guides.
• Your printer or multi-material unit already dries filament. Bambu Lab, for example, documents drying in its AMS 2 Pro and AMS HT and on the heated bed of some enclosed printers. Follow that maker's procedure and spool limits.

Ready to choose?

The filament dryer shortlist groups the ten dryers above by need: single spool, multiple spools, high temperature, and drying plus storage. For two dryers at opposite ends of one range, read SUNLU FilaDryer E2 vs S2. For four-spool dryers, read SUNLU FilaDryer S4 vs Creality SpacePi X4. If you print nylon or PC, our nylon filament guide and polycarbonate guide cover what those makers say about drying.

Quick answers

How hot does a filament dryer need to get? Hot enough for the hottest setting your filament makers publish. In the table above, every maker's PLA, PETG and TPU figure is 70 °C or below (ELEGOO gives 70 ± 5 °C for TPU), ABS, ASA and PC run from about 70 °C to 85 °C, and nylon runs from eSUN's 70–80 °C up to Polymaker's 100 °C for PolyMide CoPA.

Will my spools fit in a dryer? Measure them. Published maximum widths run from 72 mm (EIBOS Easdry) to 174 mm (EIBOS Cyclopes, one reel), and SUNLU notes that its E2 fit was tested with SUNLU spools. Bambu Lab's reusable spool, at 200 mm by 67 mm, is within every stated limit on this page.

Can I print straight from a dryer? Most of these makers say you can, but Creality recommends drying the filament thoroughly before printing from the X4, and eSUN says the eBOX Lite only maintains constant temperature and humidity during printing.

Can a filament dryer anneal prints? Of the dryers here, only the SUNLU E2 is sold as an annealing box, with SUNLU quoting 80–90 °C for 2–3 hours. SUNLU also says to use the filament maker's annealing temperatures and times.

Can I leave a dryer running unattended? Follow your dryer's manual. Polymaker's PolyDryer manual says to turn off the power when unattended and not to leave the dryer unattended in Continuous Mode.

How this page was checked

Every figure and quotation above comes from the manufacturer pages, wikis and manuals in the sources section, retrieved on 2026-10-13; the EIBOS Cyclopes and SUNLU S4 user manuals were checked on 2026-10-14. Drying settings are each filament maker's own figures for its own products, and the ELEGOO figures come from its product pages' descriptions and specifications tables. We used only visible page text and manual text. Where a figure appears only in a product image, we left it out. Where a maker's pages disagree, we report each figure and name the page. We haven't tested any of these dryers, and we didn't use customer reviews. Read more in our editorial standards and affiliate disclosure.

Dryers & dry boxes: what to check before you buy ↗