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How to use a hygrometer

Updated: October 2026

You have just unboxed a digital hygrometer. How to use a hygrometer in a UK home starts with the air you mean, not the wet glass. Put the meter in the room you live in, or in one cold corner if that corner is the question. Wait until the number stops jumping, stand back, and read the percentage. The Products Compared editorial team used the twelve amazon.co.uk listings dated 15 October 2026. There was no laboratory test. If you buy through our Amazon links, we may earn a commission at no extra cost to you. Which model to buy stays on the [hygrometer comparison](/hub/climate-measuring/hygrometer).

You have just unboxed a digital hygrometer. How to use a hygrometer in a UK home starts with the air you mean, not the wet glass.

Our top picks

TempPro TempPro TP49 (3-pack)

Best overall

TempPro TempPro TP49 (3-pack)
7.9/10about £12.61
View offer
TempPro TempPro TP157

Rank 2

TempPro TempPro TP157
8.6/10about £5.29
View offer
TempPro TempPro TP50

Alternative

TempPro TempPro TP50
7.5/10about £8.49
View offer
On this page
  1. 1.Put it on a shelf, not on the only cold surface
  2. 2.Let it settle, and do not breathe on it
  3. 3.Read the percentage, not the face
  4. 4.One meter for the room, a second for the patch

Put it on a shelf, not on the only cold surface

Yorkshire Housing’s shelf advice is an instruction for the sensor they issued. It is a sound default for the home you occupy, and it is not a rule that every cold corner is the wrong place to measure. A windowsill as the only meter matches neither Yorkshire Housing nor Cornwall Housing: the glass is colder, and sun lands on it. Bresser puts a room average on an open shelf and a second meter on the cold wall. The TP157 is not waterproof, so steam is a poor place for that model.

Let it settle, and do not breathe on it

Treat Cornwall Housing’s five minutes as that booklet’s instruction, not as a specification printed on every listing here. Fit the cell first. A blank screen is a flat cell before it is a theory about the room. One Boulton review, with humidity stuck at 99% while temperature jumped, is a fault report rather than a longer wait.
TempPro TempPro TP49 (3-pack)

Testsieger

TempPro TempPro TP49 (3-pack)
7.9/10about £12.61
View offer

Read the percentage, not the face

If the room warms and the percentage falls, the air may simply be able to hold more water. You have not necessarily lost vapour. Dew point is not on these glance meters. The Tzone THS 701 is the listing that prints dew point and wet-bulb, and this page does not teach you to calculate it. Maximum and minimum answer a different question. The TP50 names them on the highlight. A Govee alert is a phone preset after Bluetooth connects, not a meaning for the icon.

One meter for the room, a second for the patch

If both meters read high, the room air is wet. If only the wall reads high, you have found a cold surface. One TP49 reviewer advises against the fridge door, because moving the unit changed the temperature. Prefer a panel that stays still. The CNMTCCO tape and the iHMeiju dot glue are for a fixed surface. If the cold spot stays wet after you have ventilated and heated, another meter will not dry the plaster. Use the damp and mould page. Which row is a second unit is the best hygrometer page.

Common questions

Where should I put a hygrometer in a UK home?
For the home as you occupy it, use a lounge or bedroom shelf, out of sun and draughts, about a metre from doors and windows, not on the floor, and not in the bathroom. That is Yorkshire Housing’s pattern for its own sensors. Cornwall Housing allows any room you choose, at least 1.5 m up. Use the first for daily rooms and the second for one named room. Do not average the two heights.
Can I put it in the bathroom or on the windowsill?
You can, if that room or that glass is the question. A bathroom reading will not stand for the rest of the home, and a windowsill is a cold boundary rather than the air in the middle of the room. Bresser treats a sill as a poor place for the only meter. The TP157 is not waterproof, so keep that face off steam even when the bathroom is what you want to know.
How long should I wait, and will my breath change the reading?
Cornwall Housing’s booklet says 5 minutes. Boulton’s bullets say allow time to reach room temperature after unboxing. One TP49 review saw a breath effect fade within about two minutes. There is no single settle time across these twelve listings. Fit the cell, leave the meter on an open shelf, and read it when the digits stop racing. Stand back. Breath is moist air, and a sensor under your mouth will climb.
What do the dry, comfort, and wet faces mean?
In this set they mean the maker drew an icon. The thresholds are not on the listings for the TP49, the TP50, the TP157, the Boulton, the CNMTCCO, or the H5075. Read the percentage. A smile is not a pass against 40% to 60% or any other housing band, and it does not replace the number when you compare the room with that guidance.
Should I use one meter or two if a corner is mouldy?
Use one meter on an open shelf for the room average, and a second on the cold wall or behind the furniture if that patch is the worry. Bresser’s guide is that split. If the corner stays wet after ventilation and heating, the next step is the damp guidance, not a third meter on the same sill.
Can I stick it on the fridge?
A magnet is a listed mount on the TP49 and the TP50, and reviewers do use a fridge. Put it on a panel that stays still. One UK TP49 review says a fridge door changed the temperature when the door moved. Adhesive on the CNMTCCO pack is for a table, a fridge side, or a wall you are not opening. The iHMeiju dot is a vivarium mount, not a kitchen default.

Related pages

Hygrometer buying guide

Hygrometer

Best hygrometer UK for one room, a pack, or a file

Bluetooth hygrometer vs a basic meter in a UK home

Hygrometer, damp and mould: what 60% RH and 70% mean

Sources

Public UK sources used for this comparison. Listing prices, stars, and review counts are the amazon.co.uk lines from 15 October 2026.

  1. Centre for Sustainable Energy — condensation, damp and mould (retrieved 15 October 2026)
  2. East Herts Council — damp and mould (retrieved 15 October 2026)
  3. GOV.UK — health risks of damp and mould (retrieved 15 October 2026)
  4. Met Office — humidity (retrieved 15 October 2026)
  5. Property Care Association — control of dampness in buildings, January 2023 (retrieved 15 October 2026)
  6. Approved Document F, volume 1, dwellings (retrieved 15 October 2026)
  7. Consumer Rights Act 2015, section 9 (retrieved 15 October 2026)
  8. Yorkshire Housing — temperature and humidity sensor FAQs (retrieved 15 October 2026)