Loud enough that nobody puts one in a bedroom. Two things make the noise, the vacuum pump and the compressor, and they run for most of a day and a half.
What makes the noise
The vacuum pump is the constant one, a low mechanical drone that changes little through the cycle. The compressor cuts in and out like a fridge, and its fan adds a steady hiss. Together they run through the freeze and the whole drying stage.
An oil pump is generally lower pitched and more tolerable through a wall. Oil-free pumps are often described as sharper and more intrusive at the same volume, which is why owner reports disagree so much: pitch matters more than decibels.
Where the published figures stand
Manufacturer material and reseller pages usually place a home unit in the region of a dishwasher, and none of them state the distance the figure was taken at, which makes the number close to meaningless.
We have not measured this ourselves yet. When we do, it will be a reading at one and three metres, taken at the same points in the cycle, with the machine and pump type named. Until then, treat any single number you see, including ours, as a comparison rather than a specification.
A useful comparison instead
| Sound | Roughly |
|---|---|
| Quiet room | 30 dB |
| Fridge | 40 dB |
| Freeze dryer, reported range | Dishwasher territory, 50 to 65 dB |
| Vacuum cleaner | 70 dB |
| Normal conversation at 1 m | 60 dB |
Can you sleep with one running?
In the same room, no. Through a closed door in a utility room or garage, most people can. Through a thin apartment wall shared with a neighbour, expect a conversation.
The cycle runs 24 to 40 hours, so this is not a question of tolerating it for an evening. Plan the placement before you buy.
Reducing it
Put the pump on a separate anti-vibration mat from the cabinet. Much of what people hear is vibration transmitted into a floor or a hollow unit, not airborne noise.
Do not build a sealed box around it. The machine sheds heat and needs air. A three sided enclosure lined with dense material, open at the back with clearance, is the compromise that does not cook the compressor.
Questions people ask
Is it too loud for a flat? In a utility cupboard with the door shut, workable. In an open plan studio, no.
Which is louder, pump or compressor? The pump is more constant; the compressor is more intrusive when it cuts in.
Does it get louder as the cycle goes on? Not markedly. What changes is how often the compressor runs.
Safety note. Never restrict airflow around a running machine to reduce noise. Overheating a compressor is an expensive way to gain a few decibels.
What this is based on
- Manufacturer documentation and reseller listings for home freeze dryers
- Published owner reports on pump and compressor noise
- Our own SPL measurements: planned, not yet taken