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How to measure grain moisture

Updated: 22 October 2026

You already have a meter, and you want a wheat or barley figure you can set beside next Tuesday’s test and beside the merchant if they ask. How to measure grain moisture is mostly the sample and the temperature, not the button. A single fill, grain just off the dryer, or a spear that barely breaks the surface will not match a tester on the weighbridge. The hardware in this set is the [grain moisture meter comparison](/hub/measuring-equipment/grain-moisture-meter). Peter F. used AHDB’s meter and sampling pages and the seven amazon.co.uk captures, dated 21 October 2026. We did not run the meters. A qualifying purchase can earn a commission at no extra cost to you.

You already have a meter, and you want a wheat or barley figure you can set beside next Tuesday’s test and beside the merchant if they ask.

Our top picks

AMTAST AMTAST AMT65C

Best overall

AMTAST AMTAST AMT65C
7.2/10about £148.45
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Ayayu Ayayu double-rod probe

Alternative

Ayayu Ayayu double-rod probe
4.1/10about £31.40
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WapoRich WapoRich RQ-W65pro, 593 g

Best value

WapoRich WapoRich RQ-W65pro, 593 g
7.6/10about £192.69
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On this page
  1. 1.Take a sample you could take again
  2. 2.Wait until the meter and the grain agree
  3. 3.Grind, compress, or do not pretend a rod is a sample
  4. 4.Check it, then know when to stop

Take a sample you could take again

Mix before you fill the meter. Chaff and green fragments in a cup move the reading, and you will not know which way until a cleaner sample at the merchant disagrees. Three fills from the same mixed bucket, written down with the time and the crop, beat one number that feels finished. The WapoRich cups can store 250 readings and an average. An average of three careless fills is still careless. A common miss is to test the first auger run into a bin, then next week to test only the top hatch. Those are different parcels. Note the place as carefully as the percent, or the two weeks will look like drift.

Wait until the meter and the grain agree

Leave the meter with the grain until it is no longer cold from the kitchen or hot from the dashboard. If you are using a cup, set it down flat. Do not twist an offset to drag a hot sample onto yesterday’s figure. If the screen says 17.5% and the grain still feels slack, treat it as possibly wetter. The band where drying should start at once is on wheat barley storage moisture. None of the amazon rods prints AHDB’s one-minute settle for a resistance probe.
AMTAST AMTAST AMT65C

Testsieger

AMTAST AMTAST AMT65C
7.2/10about £148.45
View offer

Grind, compress, or do not pretend a rod is a sample

Do not copy a Protimeter blade routine onto HavenlyCove or onto a probe. None of the seven listings describes a grinder. If you hold a true grinder, grind the prepared sample, fill as that maker shows, compress to the stop, and repeat. The RQ-W65pro beep means the lid is tight. Fill to the mark the cup actually has, and keep the cell clean between crops. A probe only finds a wet patch. AHDB’s readings went low under about 0.5 m, and these rods do not state a length. Whether a rod can do the job is on the grain moisture probe or cup meter page.

Check it, then know when to stop

A screen at 14.8% is not proof that the heap is under 14.5%. It is a prompt to dry a little further or to ask the merchant to test. Maize is outside ISO 712, so a maize reading is not covered by that cereal check. A moisture meter does not measure mycotoxins, protein, or germination. If a hay stack is heating, call the fire service. Write down the crop, the place, the temperature and three repeats. If you have not bought yet, start with the grain moisture meter buying guide.

Common questions

How do you measure grain moisture so the next test can match?
Draw a mixed sample you could draw again, let the meter and the grain reach the same temperature, then repeat the test. AHDB’s trailer pattern is two samples of about 500 g, an aggregate of no more than 100 tonnes, and five subsamples of about 200 g mixed to about 1 kg. Repeat tests of one sample in their meter work stayed within about ±0.3%. One scoop from the surface, tested once, will not match the merchant next week.
What temperature difference throws the meter off?
A gap of about 15°C between the meter and the grain can add about ±1%, in AHDB’s meter guidance. A meter carried from a warm kitchen into a cold store, or grain straight off a hot dryer, is enough to open that gap. Leave the instrument with the grain until the two agree. If the meter is a cup that behaves like a capacitance cell, set it on a level surface before you read it.
What is different about grain just off the dryer?
It is hot, and it is often the wettest grain you will measure, which is where handheld meters are least steady. Capacitance meters in AHDB’s work read about 0.4% low straight off a hot dryer. At or above 18% moisture, meters under-read by as much as 1%. Let the sample and the meter settle before you decide the dryer has finished, and do not wind the offset to force a match with yesterday.
What does a worn grinder do to a resistance meter?
Worn blades read about 1% low in AHDB’s account, and grain that is not fully compressed also reads low. That applies to a grinding resistance meter. It does not automatically apply to every listing that uses the word resistance. HavenlyCove states resistance and does not describe a grinder. None of the seven ASINs describes a grinder. If you own a separate grinding meter, replace blunt plates rather than trimming the calibration to hide them.
How do you check the meter each year in the UK?
Compare it with an oven-tested check sample. The UK Grain Testing Network sells 180 g packs for small meters it names, including Protimeter, Sinar, Unimeter and Wile 78, and 450 g packs for larger instruments. Cereals on that scheme follow BS EN ISO 712-1:2024. Oilseeds follow ISO 665:2020. These seven amazon listings are not named there. A claim, a specification, or a germination decision still goes to a lab or to the merchant’s tester.
When should the merchant or a lab take the number instead?
When money, a written specification, or germination turns on the percent. Also when your repeats will not sit within a few tenths, or when the grain is at or above 18% and you know meters under-read in that band. The merchant’s tester is the comparison that matters at intake. A handheld meter does not show mycotoxins, and it does not replace a germination test on malting barley.

Related pages

Hay moisture meter

Grain moisture meter

Best grain moisture meter: sample, probe or grinder

Grain moisture meter buying guide: job, curve, check

Grain moisture probe or cup meter: when to use which

Wheat barley storage moisture: below 14.5% and 18%

Sources

Public UK sources from the research digest. Shelf prices and star lines are the amazon.co.uk figures for these seven listings. The price band is this set, not a market average. A seller’s ±0.5% line is not an oven result.

  1. AHDB: how to use a grain moisture meter (retrieved 22 October 2026)
  2. AHDB: grain storage moisture targets (retrieved 22 October 2026)
  3. AHDB: pests, fungi and ochratoxin A (retrieved 22 October 2026)
  4. AHDB: hazards in longer-term grain storage (retrieved 22 October 2026)
  5. FSA: mycotoxins publications (retrieved 22 October 2026)
  6. AIC Grain storage guide 2023 (retrieved 22 October 2026)
  7. ISO 712-1:2024 cereal oven method (retrieved 22 October 2026)
  8. Devon and Somerset Fire and Rescue Service: storing hay safely (retrieved 22 October 2026)