The short answer (checked 28 October 2026)
- The 40% to 60% humidity band printed on most meters is a sensible target, but UK health guidance calls it the range that minimises most adverse effects. It is not a legal or medical threshold.
- Best all-rounder: Govee Bluetooth hygrometer. It states ±3% RH and keeps two years of readings you can export, so you can see whether a room goes damp overnight.
- Cheapest per room: EEEKit 8 pack at £1.75 a room, though it states the loosest tolerance here, ±5% RH.
- The audit finding: of the first 20 unsponsored Amazon UK hygrometer listings, 5 state no accuracy figure at all, including the TempPro TP49, the best seller in the search. Ten of the 15 that do state one give ±5% RH, which is half the width of the whole 40% to 60% band.
If you have condensation on the windows or a patch of mould in a corner, the first useful number is how humid the room actually is. A hygrometer gives you that for a few pounds. It tells you whether the problem is the air, which a dehumidifier or more ventilation can fix, or a cold surface, which needs heat or insulation.
The catch is accuracy. Most of these meters cost less than a sandwich, and how close the reading is to the truth decides whether it can tell you anything about a band only 20 points wide.
Prices in this table come from Amazon and are refreshed at least once a day, with the date of the last update under the table. The cost-per-use and running-cost figures on this page use prices Look Into read on 28 October 2026, so they can differ from today's price.
As an Amazon Associate, Look Into earns from qualifying purchases. Product prices and availability are accurate as of 28 October 2026 and are subject to change.
Prices and specs last checked by Look Into on 28 October 2026 · next check 23 December 2026 · how we picked
What humidity should your home be?
The figure you will see everywhere is 40% to 60% relative humidity. The UK Health Security Agency's Health Effects of Climate Change report, chapter 5 on indoor environmental quality, gives the reasoning on page 17. It says most adverse health effects caused by relative humidity "would be minimised by maintaining indoor levels between 40% and 60%". It also quotes the indoor air scientist William Nazaroff's advice to "keep it dry (relative humidity: 40% to 60%)".
The same report is careful about what that band is not. On page 16 it says studies link respiratory illness to damp and mould, but that more research is needed on the causes, "with a lack of health-related thresholds for moisture in buildings". So 40% to 60% is good practice from the evidence, not a line where a home becomes unhealthy. A reading of 62% in a bathroom after a shower is normal. A bedroom that sits at 70% all night, every night, is worth acting on.
Why a cold room reads damp: humidity and dew point
Relative humidity is relative to temperature. The same air reads drier when warmed and damper when cooled. Condensation forms on any surface colder than the air's dew point, the temperature at which that air becomes saturated. Single glazing, a cold outside corner or the back of a wardrobe against an outside wall are the usual places.
| Room air | 40% RH | 50% RH | 60% RH | 70% RH | 80% RH |
|---|---|---|---|---|---|
| 18°C | 4.2°C | 7.4°C | 10.1°C | 12.4°C | 14.5°C |
| 20°C | 6.0°C | 9.3°C | 12.0°C | 14.4°C | 16.4°C |
Read it like this. A bedroom at 18°C and 60% humidity will put water on any surface below about 10°C. On a frosty night that includes most single-glazed windows and some old double glazing. Drop the humidity to 50% and the surface has to fall below 7.4°C before it gets wet.
This is also where accuracy starts to matter. A meter rated ±5% RH that shows 60% at 18°C means the true figure could be anything from 55% to 65%. That puts the dew point anywhere between 8.8°C and 11.3°C, a spread of two and a half degrees.
What 20 listings say about accuracy
We read the first 20 unsponsored Amazon UK results for "hygrometer" on 28 October 2026. We counted claims in the product title, the About this item bullets, the description, the product overview and the brand content. We left out reviews, questions and images.
- 15 of 20 state a humidity tolerance.
- 5 of 20 state none. That includes three listings for the TempPro TP49, the search's best seller with more than 4,000 bought in the past month, which says "Accurate and fast response" and gives no figure.
- Of the 15 with a figure, 10 say ±5% RH, 2 say ±3%, 2 say "±2% to 3%" and 1 says ±2%.
- 4 of 20 say under what conditions the tolerance holds: three at a room temperature of 25°C, one between 20% and 80% humidity.
- 3 of 20 mention calibration in any form.
A ±5% meter has an error range of ten points, half the width of the 40% to 60% band it is meant to place you in. That does not make cheap meters useless. They are good at showing change. If your bedroom reads 58% at bedtime and 72% at 7am on the same meter, that rise is real even if both numbers are a few points out. What a loose meter cannot do is settle whether a room is at 58% or 62%.
How we made this guide
We picked from the 20 listings above, opened every product page on 28 October 2026, and ranked on two things. First, whether the maker states a humidity tolerance, and how tight it is. Second, what you get for the money: history logging, alerts, dew point, or several rooms covered. Cost per room is the price we read that day divided by the number of units in the pack. Look Into has not handled these meters. The tolerances are the makers' own claims, not our measurements.
| Meter | Stated humidity tolerance | Units | Cost per room | Extras |
|---|---|---|---|---|
| Govee Bluetooth | ±3% RH | 1 | single unit | App, alerts, 2 years of history to export |
| TempPro TP157 | ±2% to 3% RH | 1 | single unit | 10 second refresh |
| Vaikby 4 pack | ±2% RH | 4 | £2.50 | CR2032 batteries included |
| EEEKit 8 pack | ±5% RH | 8 | £1.75 | Runs on AG13 button cells |
| Protmex HT607 | ±3% RH (20% to 80%) | 1 | single unit | Handheld, shows dew point and wet bulb |
| TempPro TP49 | not stated | 1 | single unit | Dry, comfort and wet face icons |
The six we would look at
Govee Bluetooth Thermometer Hygrometer
Price: check the live price on Amazon · ±3% RH stated · app with alerts
The history is the reason to buy it. Damp problems are about what happens overnight, when the heating is off and people are breathing in a closed room. A display only shows you the moment you look. The listing says you can export the past two years of readings, and alerts can warn you when a room passes a level you set. More than 2,000 bought in the past month.
The catch: it is Bluetooth, so the phone has to be in range to sync, and alerts need the app. The ±3% figure comes with no stated conditions. The listing also calls the sensor "Swiss-made" without naming the maker.
Check price on Amazon →TempPro TP157 Digital Hygrometer
Price: check the live price on Amazon · ±2% to 3% RH stated
The cheapest single meter in the search, and one of the few with a tolerance tighter than ±5%. It refreshes every 10 seconds, which helps when you are walking it from room to room to find the damp one. More than 1,000 bought in the past month.
The catch: "±2% to 3%" is a range of tolerances, not one figure, and the listing does not say when each applies. It keeps no history.
Check price on Amazon →Vaikby Room Thermometer Hygrometer, 4 pack
Price: check the live price on Amazon · £2.50 a room on 28 October 2026 · ±2% RH stated
Four meters with the tightest stated tolerance in the 20 listings, at £2.50 a room. One in each bedroom, one in the bathroom and one in the room with the worst windows shows you which room is the problem. That is more useful than one accurate meter in the hallway. CR2032 batteries are included.
The catch: ±2% from an unbranded four pack at this price is a claim we cannot check, and the listing gives no conditions for it. If two of the four sit side by side and disagree by more than four points, at least one is outside its own stated tolerance.
Check price on Amazon →EEEKit Digital Thermometer Hygrometer, 8 pack
Price: check the live price on Amazon · £1.75 a room on 28 October 2026 · ±5% RH stated
Small stick-on meters at £1.75 each, small enough for inside a wardrobe, a kitchen cupboard on an outside wall or a loft hatch. Those are the hidden places where mould starts. For spotting which corner is damper than the rest, a loose tolerance matters less than coverage.
The catch: ±5% is the loosest tolerance on this page, so treat the numbers as a comparison between spots rather than a verdict on any one of them. They run on AG13 button cells, which are fiddlier to buy than AAAs.
Check price on Amazon →Protmex HT607 Temperature Humidity Meter
Price: check the live price on Amazon · ±3% RH stated between 20% and 80%
A handheld meter that works out dew point and wet bulb temperature for you, so you can see straight away how cold a surface needs to be before it gets wet. It is the only listing of the 20 that states its humidity tolerance across a named humidity range, and it gives a looser ±4% outside that range rather than leaving it unsaid.
The catch: it costs several times as much as the others, and it measures air, not walls. You still need a surface temperature to compare with the dew point, and this meter does not read surfaces.
Check price on Amazon →TempPro TP49 Digital Hygrometer
Price: check the live price on Amazon · tolerance not stated
The meter most people buy, with more than 4,000 bought in the past month on one listing alone. Its dry, comfort and wet face icons make it easy for anyone in the house to read at a glance.
The catch: none of the three TP49 listings we read states a humidity tolerance. Its stablemate, the TP157, states ±2% to 3%. If the number matters to you, for a landlord conversation or a damp survey, buy a meter that puts its accuracy in writing.
Check price on Amazon →Getting a useful reading
- Put it at head height away from radiators, windows, kettles and outside walls. Readings next to any of those tell you about that spot, not the room.
- Give a new or moved meter some time to settle before trusting the first number.
- Look at the pattern, not one reading. Note bedtime and first thing in the morning for a week.
- To compare meters, sit them side by side for an hour. If they disagree by more than their stated tolerances combined, one of them is wrong.
If the readings say the air is damp, the next step is ventilation or a dehumidifier. Our guide to what size dehumidifier you need starts from exactly this kind of reading. If the air is fine but one wall stays wet, the problem is the wall, and our guide to stopping condensation on windows covers what each fix costs.
Questions people ask
Is 70% humidity in a room too high?
For an hour after a shower or cooking, no. If a room sits at 70% for long stretches, it is above the 40% to 60% range that UK Health Security Agency guidance says minimises most adverse effects. At 18°C, 70% air will condense on any surface below about 12°C.
Are cheap hygrometers accurate?
Most cheap meters state ±5% RH. Ten of the 15 listings we read that gave any figure said that, and five of 20 gave no figure at all. That is good enough to show changes over time and to compare rooms, but not to tell 58% from 62%.
Digital or analogue?
None of the top 20 results was an analogue dial meter. One digital listing claims to be better than analogue meters but gives no figure for the comparison. On stated accuracy alone, the digital meters here are the only ones that put a number on it.
Can a hygrometer tell me if a wall is damp?
No. A hygrometer measures the air. Damp in a wall needs a different instrument, and even then the reading needs care, because most cheap moisture meters are set up for wood rather than plaster or brick.
Related reading
- Best dehumidifiers UK 2026: ranked by what a night costs to run
- Best moisture absorbers UK 2026
- Best window vacuums UK 2026
- Best mould removers UK 2026
- Best humidifiers UK, for rooms that are too dry
Sources
- UK Health Security Agency, Health Effects of Climate Change in the UK: 2023 report, chapter 5, read 28 October 2026. Page 16 (lack of health-related thresholds for moisture in buildings) and page 17 (indoor levels between 40% and 60%).
- Amazon.co.uk search results for "hygrometer", first 20 unsponsored results, read 28 October 2026, plus each product page opened that day.
- Dew points worked by Look Into with the Magnus approximation, constants 17.62 and 243.12°C.
Look Into is an Amazon Associate and earns from qualifying purchases. That does not change which products we pick or what we say about them. The comparison table above pulls live prices from Amazon. The cost-per-room figures use prices read on 28 October 2026, so they can differ from today's price.