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Catch weight: why you are invoicing the wrong number
Catch weight means a product is sold in whole units, a box of fish, a side of beef, but priced by weight, since no two units weigh exactly the same. The only correct invoice figure is the actual weight recorded at the pick, never the nominal weight printed on the box and never an average taken across a batch.
What catch weight actually means
Some products cannot be sold in fixed units the way a tin of tomatoes can. A whole salmon, a side of beef, a wheel of cheese - each one is naturally a different weight from the next, because it came from a different animal or a different fish, and there is no manufacturing process that makes them identical. The trade solves this by selling the item as a unit, a box, a side, a whole fish, but pricing it by weight: so much per kilo, applied to whatever that particular unit actually weighs.
Where the wrong number comes from
A box of fish arrives with a nominal weight printed on it by the supplier, say ten kilograms, because that is roughly what a box of that size and species usually weighs. It is a label, not a measurement of what is inside this particular box, which might weigh nine point six kilograms or ten point four. Some wholesalers invoice the nominal figure because it is the easiest number to type, and it is quietly wrong on nearly every box, in both directions.
A second version of the same mistake is worse: taking an average across a batch of boxes and applying that average to all of them, on the reasoning that it evens out. It does not even out for the customer who happens to get the heaviest box, and it does not even out for the wholesaler on the box that was actually lighter than the average suggested. Averaging spreads the error rather than removing it, and it also breaks the audit trail - nobody can point to the number on the scale and say that invoice is correct, because there was no number on the scale.
Catch weight has one correct answer, and it is whatever the scale said for that exact box, not the label and not the average.
A worked example
Take ten boxes of whole sea bass, each nominally ten kilograms, sold at a hypothetical six pounds a kilo. Invoiced at the nominal weight, every customer pays for exactly ten kilograms, whatever they actually received. In reality the boxes might run anywhere from nine point four to ten point six kilograms, because fish do not come out of the sea to a fixed size. The customer who receives the nine point four kilogram box has been overcharged for six tenths of a kilogram, a little over three pounds on that one box. The customer who receives the ten point six kilogram box has been undercharged by the same amount. Across the wholesaler's whole week those errors might roughly cancel out in aggregate, which is exactly why averaging feels harmless from the office - but no single customer experiences the average. Each one only ever sees their own box, correctly weighed or not.
None of this requires exotic equipment. A set of scales at goods-in and another at the pick bench, and a habit of recording what they say against the specific unit rather than the product in general, is the entire fix. The discipline is simple. What is hard is building the invoicing system to actually hold a different number for every single box rather than one number per product line, which is the part most off-the-shelf systems were never asked to do.
Why it matters more than it looks
On a single box the difference between nominal and actual weight is small change. Across a week of deliveries, applied consistently in one direction, it is not. A wholesaler who habitually invoices the nominal weight on catch-weight lines and finds that boxes usually run a little heavier than the label is quietly giving away margin on every one of those lines, invisibly, because the invoice never disagreed with the label enough to get noticed.
The other direction is worse for trust than for margin: a kitchen that weighs its own deliveries, which the better-run ones do, will eventually catch a wholesaler invoicing a nominal weight that is consistently higher than what actually arrives. That is not a pricing error any more. That is the thing that ends a relationship with a customer who had no reason to doubt the invoice until they checked it.
What correct actually requires
Getting it right means the weight is captured at the moment it is known - at goods-in for what was bought, and again at the pick or the pack for what goes out - and the invoice line is generated from that recorded figure and nothing else. It means the system used to invoice has to be able to hold a different weight against every single unit of a catch-weight product rather than one weight per product code, which is a different kind of record-keeping than pricing a tin of tomatoes, and one a lot of off-the-shelf ordering software was never built to handle, because most of what it sells is fixed-unit product.
Plainly
What it will not do on its own
- It will not weigh anything for you - a scale at goods-in and at the pick still has to produce the real number.
- It does not retrospectively correct a weight that was never recorded. A catch-weight line invoiced from a guess stays a guess in the record.
- It does not decide your tolerance for a supplier's nominal weight running consistently high or low - that is a conversation with the supplier, not a system setting.
- Non-catch-weight lines are unaffected by any of this - most of a typical order is fixed-unit product and prices exactly as ordered.
Questions people ask
- What does catch weight mean in food wholesale?
- It describes a product sold as a whole unit, a box, a side, a whole fish, but priced by weight rather than by the piece, because no two units weigh the same. The correct invoice price is the per-kilo rate applied to that specific unit's actual weight, not a standard weight assumed for the product.
- Should I invoice the nominal weight printed on a catch-weight box?
- No. The nominal weight is a label the supplier attached for convenience, not a measurement of the box in front of you. Invoicing it instead of the actual weight recorded at goods-in or at the pick is a quiet, consistent error that runs in one direction or the other on every single box.
- Is it acceptable to invoice catch-weight lines on an average weight across a batch?
- No. Averaging spreads the error across every box rather than removing it, overcharges whoever received the lighter units and undercharges on the heavier ones, and leaves no scale reading to point to if a customer questions the figure.
- Why can't most off-the-shelf ordering software handle catch weight properly?
- Because it was built to price a fixed unit against a single product code, and catch weight needs a different real weight recorded against every individual unit sold - a different kind of record-keeping most general ordering systems were never designed to hold.
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