Hygrometers
A hygrometer for filament storage shows the humidity inside your dry box, storage tub or vacuum bag at a glance. Choose a round or rectangular mini hygrometer, each in black or white, that reads temperature as well.
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Why use a hygrometer for filament storage?
You cannot see moisture creeping into a roll until prints start popping and stringing. A small hygrometer inside your storage shows the humidity around the filament, so you can refresh desiccant or fix a leaky seal before the roll suffers. Both of our mini hygrometers read temperature and humidity, and they are best used for watching trends.
Round or rectangular mini hygrometer?
| Model | Front | Rear and depth | Colours |
|---|---|---|---|
| Mini Hygrometer (round) | 45 mm diameter | 41.5 mm diameter, 16 mm deep overall (rear section 14 mm) | Black or white |
| Mini Hygrometer (rectangular) | 48 x 28.5 mm | 45 x 26 mm, 16 mm deep overall (rear section 14 mm) | Black or white |
Both work the same way, so choose by the space available. The rectangular model measures only 28.5 mm on its short side, which suits narrow gaps, while the round model is a compact disc. The listed front and rear measurements also make it easy to model a printed holder or recess.
Where to place a humidity meter
- Dry boxes: mount it where you can read it without lifting the lid, so checking does not let damp air in.
- Vacuum bags: slip it in beside the spool and desiccant bag before you seal and pump out the air.
- AMS units: a compact hygrometer can sit with the spools in an automatic material system such as a Bambu Lab AMS, as long as the measurements suit the free space.
- Storage tubs: place it at spool height and a little away from the desiccant, so it reads the air around the filament.
Reading the numbers and refreshing desiccant
A well sealed container with fresh desiccant should read noticeably drier than the room around it. If the reading drifts back towards room humidity and stays there, the seal is leaking or the desiccant is saturated. Our article on how to store filament in Australia's humidity explains why this shifts with the seasons.
Check the lid or bag seal first, then swap in fresh Silica Gel Desiccant Bags. Silica gel can generally be dried out and reused, but fresh bags are the quickest fix. For a complete setup, see our vacuum storage guide.
Buying a hygrometer for filament storage
Both mini hygrometers come in black or white, and one per dry box or tub is enough. Add desiccant to the same order, and shipping is free Australia-wide on orders over $299 (excluding PO Boxes).
Hygrometer FAQs
How accurate are these mini hygrometers?
Both models are listed with an accuracy of ±1°C for temperature and ±5% for humidity. That is plenty for filament storage, where the trend matters more than the exact number. If two units side by side disagree slightly, compare each against its own earlier readings.
What humidity should I keep my filament at?
As low as you can practically manage, and steady. A sealed bag or box with fresh desiccant should sit well below the humidity of the room, and nylon, PVA, TPU and PETG gain the most from staying dry. If a roll has already absorbed moisture, dry it using the guidance on its product page before storing it again.
Will a hygrometer fit inside a vacuum bag or AMS?
They are compact. The round model is 45 mm across and the rectangular model is 48 x 28.5 mm, and both are 16 mm deep. Compare those measurements with the free space beside your spools before ordering, especially in an AMS or a tightly fitted dry box.
Do I still need desiccant if I have a hygrometer?
Yes. A hygrometer only measures humidity; it does not remove any moisture. Desiccant does the actual drying work inside a sealed bag, box or tub, and the hygrometer tells you when that desiccant needs replacing, so the two work best as a pair in any dry storage setup.