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Humidity meters for UK homes

Choose a readable humidity meter, understand its uncertainty and put it somewhere useful.

By Dehumidifier UK · Updated 6 October 2026 · Sources linked below

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Our answer

For a simple room check, a standalone temperature/RH display is enough. Choose the TFA EXACTO if you want a published accuracy range and min/max functions; choose SwitchBot Meter Plus if you want a history in an app. The TFA 30.5027 is a simpler display option. None diagnoses damp inside a wall.

Three useful options

MeterWhy consider itWhat to check
TFA EXACTO 30.5047Display, trend arrows, min/max and offset adjustment. Stated ±3 percentage points RH at 35–75%, otherwise ±5.Check the exact 30.5047 version; do not confuse an adjustable offset with a calibration certificate.
SwitchBot Meter PlusLocal screen, Bluetooth history and data export. Typical stated ±2 points RH at 10–90% RH.A compatible hub is needed for remote internet access; Bluetooth alone is not Wi-Fi.
TFA 30.5027Straightforward temperature/RH display and stored minimum/maximum.The inspected product page did not establish accuracy; do not treat its one-per-cent display as one-point accuracy.

Our recommendation by use case

Choose the EXACTO if you want to walk into a room, read its conditions and see whether the last day was wetter or drier. Choose the SwitchBot if the question is what happens while the room is empty, during laundry or overnight. An app history can reveal a pattern that a one-off glance misses. A basic meter is reasonable if you will record readings yourself and do not need connected features.

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A hygrometer is different from a damp meter

A hygrometer measures the relative humidity of air. A pin or contact moisture meter examines a material, and its readings depend on material type and the instrument. Buying a humidity meter will not prove whether staining comes from a leak, penetrating damp or condensation. Persistent building symptoms should be investigated rather than diagnosed from one number on a screen.

Accuracy, resolution and agreement

If a meter displays 60% RH with a stated accuracy of ±3 percentage points under the relevant conditions, the true value may be around 57–63%. A display that changes in steps of 1% is not automatically accurate to one point. Two meters can disagree within their respective specifications; place them side by side away from heat and airflow before judging the difference.

Do not alter an offset simply to make two readings agree. Agreement with a second consumer device is not traceable calibration. For routine household decisions, a consistent position and a trend over several days can be more useful than chasing every one-point change.

Where to put it

  1. Choose a representative position in the occupied part of the room, away from radiators, direct sun, windows and the dehumidifier outlet.
  2. Let the sensor settle after moving it, following its instructions. Record the temperature with every RH reading.
  3. Read it at similar times each day and note showers, cooking, laundry, heating and ventilation.
  4. For condensation near a cold wall, compare a second position nearer the problem, keeping the sensor clear of a wet surface. Label which reading is which.

What reading should prompt action?

Around 40–60% RH is a useful household reference, with temperature and duration considered. A brief rise after a shower differs from hours of high humidity. Even a room-average reading in that band can coexist with condensation on a very cold window. Use the ideal-humidity guide for the context and meter setup guide for a repeatable routine.

What the shortlist does not claim

These instruments have not been independently checked by us against a reference sensor. Their specifications are manufacturer claims. The smart meter option does not measure carbon monoxide, carbon dioxide or mould spores. If those are your concerns, you need an instrument intended for that measurement.

Sources and evidence

  1. SwitchBot Meter Plus UK specifications
  2. TFA EXACTO 30.5047
  3. TFA 30.5027 thermo-hygrometer
  4. GOV.UK: addressing damp and mould in homes
  5. Dartford Borough Council: damp, mould and condensation

Sources checked 6 October 2026. Manufacturer specifications are claims under their stated conditions; they are not our household measurements.