How to weigh grain without a weighbridge

You can get a usable grain weight without owning a weighbridge — the question is how accurate the job needs it to be. Checking a merchant's figures needs a better number than settling which field did best, which in turn needs a better number than "roughly what's in the shed". Here's the ladder, from most accurate to least.

Method	Typical accuracy	Cost	The catch
Merchant intake weights	Bridge-accurate	Free	Arrives late, and it's their number
Public weighbridge	To ~20kg	£20–£30 + VAT per load	Too slow at harvest pace
Loader weighing system	Within a couple of percent	A few thousand pounds fitted	Weighs what's loaded out, not what came in
Combine yield monitor	Within a few percent — if calibrated	Comes with the combine	"If calibrated" carries the sentence
Trailer counts × honest average	5–10%	Free	Depends on the honesty
Heap volume × bulk density	10–20%	Free	It's a guess with arithmetic attached

Merchant intake weights

Every load you sell gets weighed on the buyer's verified bridge, and those weights are accurate. For a farm that sells everything off the combine, intake weights are a complete record — free, and better than anything you'd produce yourself.

Two limitations. The number arrives after the grain has gone, so it steers nothing during harvest. And it's the buyer's number: if you ever want to question it, you need an independent weight from before delivery, not after. Intake weights also come per contract, not per field, so they'll never tell you which end of the farm grew the wheat.

Public weighbridge

The accurate independent option: to around 20kg, on a verified bridge, for £20–£30 plus VAT per load (two weighings). Where to find one and how it works is in the public weighbridge guide.

The problem is pace. When trailers are coming every ten minutes, a detour to a bridge that keeps office hours isn't a system, it's a hobby. Public bridges are for spot checks, disputes, and calibrating the cheaper methods below — weigh five representative loads and you've bought yourself a trustworthy average for £150 or so.

Loader weighing systems

Weighing kit on the loading shovel or telehandler — typically a few thousand pounds fitted — weighs each bucket as it lifts. Accuracy within a couple of percent is realistic with a calibrated system and a careful operator.

The quirk: it weighs grain going out of the store onto lorries, or moving between sheds, not what came in off the field. That makes loader scales strongest for outgoing loads — checking against haulier and merchant figures — and for reconciling a shed as it empties.

Combine yield monitor

The yield monitor estimates crop flow as you cut, and maps it. Calibrated against real load weights, a few percent is achievable; uncalibrated, it can be out by 10% or more and — worse — differently wrong between crops and moistures. The full comparison is in yield monitor vs weighbridge.

Note the circularity: calibrating the monitor needs real weights from somewhere — a public bridge, a merchant's intake, a neighbour's bridge. Do that once or twice a season per crop and the monitor becomes genuinely useful for field-by-field comparison, which is the one thing intake weights can never give you.

Trailer counts with an honest average

The old method, and better than its reputation when done straight. Count every load per field, weigh a handful of representative loads to establish a true average (one public bridge visit does it), and multiply. The discipline is admitting the three-quarter loads — record fills as they were, not as they looked from the combine seat.

Expect 5–10% at field level. That's plenty to rank fields and spot a disaster, not enough to argue with a merchant. Turn the counts into per-hectare figures with the field yield calculator.

Heap volume and bulk density

The last resort: measure the heap, estimate its volume, multiply by bulk density — wheat stores at roughly 750kg per cubic metre, barley and OSR less. Honest error is 10–20%, because heaps aren't neat prisms and density varies with moisture and sample. The grain store capacity calculator does the arithmetic. Use it for "will the next field fit" and rough stock checks; never for anything with money attached.

Whatever the method, write it down per load

A weight that isn't recorded against a field and a destination is a number that evaporates. Trailer counts only work if someone counts; monitor data only helps if it's calibrated and kept; intake weights only reconcile if you know which loads went where. The recording habit matters more than which rung of the ladder you're on — how to track harvest covers building it. It's the problem we built Harvestt around, for what that's worth: the method can be humble as long as the record is complete.

Frequently Asked Questions

What's the most accurate way to weigh grain without a weighbridge?

A public weighbridge — verified, independent, and accurate to around 20kg — at £20–£30 plus VAT per load. For whole-harvest coverage rather than spot checks, merchant intake weights are equally accurate and free, but they arrive after the grain has gone and they're the buyer's numbers.

How accurate is a combine yield monitor?

Within a few percent when calibrated against real load weights once or twice a season per crop. Uncalibrated, errors of 10% or more are common, and they differ between crops and moisture levels, which quietly wrecks field comparisons.

How do I estimate how much grain is in a shed?

Estimate the heap's volume and multiply by bulk density — roughly 750kg per cubic metre for wheat. Expect 10–20% error. It's fine for checking whether the next field will fit, and useless for settling anything financial.

Is counting trailer loads accurate enough?

For ranking fields and rough totals, yes — around 5–10% if you weigh a few loads to set an honest average and count part-loads as part-loads. For selling grain or disputing a merchant's weight, no.