What is Inventory Shrinkage and How Do You Calculate It?

You run a batch of cold process soap. Your recipe calls for 500g of lye and 800g of oils. You finish the batch, clean up, and move on. But you used a bit more of each ingredient than planned, residue in the pot, a small spill, slightly generous measuring. You didn’t update your inventory records to reflect any of it.

Multiply that across every batch for six months. Suddenly your stock counts are noticeably off, and you can’t figure out why.

That’s inventory shrinkage. And if you manufacture what you sell, it probably looks nothing like the retail version you find when you Google it.

Last updated: March 2026

What is inventory shrinkage?

Inventory shrinkage is the difference between what your records say you have and what’s actually sitting on your shelf.

In retail, the conversation is mostly about shoplifting and employee theft. For small manufacturers, the story is different. Your materials disappear through the production process itself, waste, spillage, spoilage, and miscounts all chip away at your stock without you always noticing.

A spilled jar of fragrance oil. A candle pour that seized. A batch of resin that cured badly. Components that fell and got swept up with the floor dust. None of that is theft. But it all creates the same problem: your books say you have materials you don’t actually have.

Why shrinkage looks different when you manufacture

Most articles about inventory shrinkage are written for retailers with stockrooms full of products. You’re not running a stockroom. You’re turning raw materials into finished goods, batch by batch, and the losses happen during that process.

For small-batch production, the main sources of shrinkage are:

Production scrap, every batch generates waste that can’t go back into the bottle or the bag. Soap trimmings. Candle wax coating the melting pot. Clay that dried while you worked. This is the normal cost of making things in small batches. But if your recipe doesn’t account for it, it shows up as unexplained shrinkage every stocktake.

Failed batches, soap that didn’t trace. Candles that frosted or had sinkholes. Resin that stayed tacky. Sometimes you can salvage it. Often you can’t. The whole batch is a loss, and every gram of ingredient in it has left your inventory with no record.

Spoilage, butters, carrier oils, fragrance concentrates, dried botanicals. They all have shelf lives. Buy in bulk to save money (which most producers do), and you’re carrying spoilage risk on every shelf.

Spillage and handling damage, a dropped bottle, a cracked mould, a bag of herbs that ripped open. Accidents happen constantly in small-batch production. None of it gets recorded, so all of it becomes shrinkage.

Measurement over-run, your recipe says 30ml of fragrance oil. In practice, you pour 32ml. Most days you don’t notice. But over a year of weekly batches, that’s a meaningful quantity of unrecorded usage.

Recording errors, a missed purchase entry, a forgotten batch, a stocktake count that was one short. Manual record-keeping always has this risk.

Why it matters for your business

It makes your product costs wrong

If your soap recipe theoretically uses $3.50 in materials, but in practice you’re losing 10% of each ingredient to waste and spillage, your real material cost is closer to $3.85. That’s money you’re absorbing on every single sale if you haven’t built it in.

Calculating accurate COGS requires knowing how much material you actually use, not just what your recipe says. Shrinkage is part of that picture, and if it’s not in the numbers, your pricing is off.

It makes your inventory unreliable

When your stock records don’t reflect reality, everything downstream gets shaky. Reorder points trigger at the wrong time. Production planning falls apart. You order materials thinking you’re nearly out, but half the problem is unrecorded waste from weeks ago.

It creates tax headaches

If your inventory counts are wrong, your cost calculations are wrong, which means your Schedule C reporting is wrong. Material write-offs and waste that aren’t recorded don’t get deducted. That’s money you’re leaving on the table.

Common causes to watch for

Scrap that’s not in your recipe

Every manufactured product generates scrap that can’t go back into inventory. Soap off-cuts from squaring up a loaf. Wax coating on the pour pot. Yarn tangled at the end of a run. Clay that hardened on the workbench.

This isn’t careless waste, it’s the normal cost of production. But if your bill of materials doesn’t account for it, it’ll show as unexplained shrinkage every time you do a count.

Failed batches

Open the mould and something’s wrong. It happens. Sometimes you rebatch. Often you bin the whole thing. Every ingredient in that batch is gone from your inventory, but unless you record it as a loss, your records won’t know.

Expiry and spoilage

Fragrance oils go off. Carrier oils go rancid. Dried herbs lose potency. If you buy seasonal materials in bulk, you’ll have stock sitting longer than intended. When those materials aren’t usable anymore, your physical inventory is lower than your records, but no adjustment gets made until a stocktake.

Dating your materials and using first-in, first-out rotation reduces this significantly. So does buying smaller quantities more often for ingredients that spoil fast.

Measurement creep

Your recipe is precise on paper. In production, you’re working fast, and when you’re eyeballing ingredients instead of weighing them, you’re almost always using slightly more than the recipe says. That difference is real material leaving your inventory unrecorded.

A gram scale for every ingredient isn’t just about product consistency. It’s also the simplest way to cut measurement-related shrinkage.

Recording errors and stocktake miscounts

These compound over time. One missed batch entry. One purchase that didn’t make it into your system. A physical count that was two units short. Each small error is minor on its own, but six months of them together produces a real discrepancy.

How to calculate inventory shrinkage

Two calculations are worth knowing: total shrinkage and shrinkage rate.

Total shrinkage

Inventory Shrinkage = Recorded Inventory Value − Actual Inventory Value

Your “recorded” figure is what your inventory system says you should have. Your “actual” figure comes from a physical count. The difference is your shrinkage.

For example: your records say $2,400 in raw materials. After physically counting everything, you have $2,100. Your shrinkage is $300.

Shrinkage rate (%)

Shrinkage Rate = (Shrinkage ÷ Recorded Inventory Value) × 100

Using the same example: ($300 ÷ $2,400) × 100 = 12.5% shrinkage rate.

The rate is more useful than the dollar figure because it scales with your inventory size and lets you compare across time periods.

A candle-making worked example

You run a small candle business. At the start of the quarter your inventory records show 6kg of coconut wax, 500ml of fragrance oil, and 60 wicks, a total material value of $210. After a physical count at the end of the quarter, you find 5.1kg of wax, 415ml of fragrance oil, and 58 wicks, worth $178.50.

Shrinkage = $210 − $178.50 = $31.50
Shrinkage Rate = ($31.50 ÷ $210) × 100 = 15%

That’s above the typical 3-8% range, which points to wax loss in the pour pot and fragrance oil over-measuring. Building a 10-12% scrap buffer into your wax and fragrance recipe quantities would bring those losses into your pricing rather than absorbing them silently in every batch.

What’s a realistic rate for small manufacturers?

Retail benchmarks won’t apply here. Big box retailers target under 1.5%. For small-batch production with genuine material waste, 3-8% is realistic depending on what you make.

High-waste products (cold process soap, candles, ceramics, clay) typically run toward the higher end. Precision work like jewellery with weighed components can run lower. The goal isn’t zero. It’s knowing your number, accounting for it in your pricing, and watching it over time.

How to record shrinkage in your bookkeeping

Different types of shrinkage get handled differently.

Production scrap

The cleanest approach: build it into your bill of materials as part of the quantity each recipe consumes. If you consistently lose 8% of your soap oils to pot residue and off-cuts, put the real-world quantity in the recipe rather than the theoretical one. Every manufacture then deducts what you genuinely use, not the perfect-batch amount.

This is more accurate than trying to record each individual scrap event, which no one actually does in real production.

Failed batches

Record these as they happen. When a batch fails, log the production run with the materials it consumed and the actual quantity produced, so the ingredients leave your inventory even though little or nothing saleable came out of it. Do it right then, while you’re cleaning up, not at the end of the week when you’re trying to remember.

If you record failed batches consistently, your stocktake discrepancies shrink considerably, because the losses are already in the system.

Spoilage

Reconcile spoiled materials through a stocktake rather than quietly reducing the quantity on hand. Counting the shelf and letting the system record the correction gives you a dated record of where the loss happened, which tells you something useful over time: are you buying too much? Is your storage temperature a problem? Are certain suppliers sending materials with shorter shelf lives than advertised?

A pattern in your spoilage data is worth knowing about.

Miscounts from prior stocktakes

If a physical count reveals a discrepancy you can’t explain, review your purchase history and recent manufacture records first. Sometimes the answer is right there, a batch that wasn’t logged, a purchase that was entered twice. If you can’t find the source, adjust your records to match physical reality and note it so you can watch for a pattern.

For a deeper look at tracking down unexplained stock gaps: stock discrepancies, 10 reasons your count may be wrong.

How to reduce shrinkage going forward

You won’t get to zero. But you can get it under control.

Measure accurately. A scale for every ingredient, every batch. Weighing instead of eyeballing is the single fastest way to cut unrecorded usage.

Record as you go. Log each manufacture in your inventory system when you make it, not hours later when the details blur. The delay is where errors creep in.

Build waste into your recipes. Use realistic quantities in your bill of materials for each product. Your deductions then reflect how you actually work, not a theoretical perfect batch.

Date your materials. Especially oils, botanicals, and fragrance concentrates. First in, first out, use older stock before opening new containers.

Do regular mini-stocktakes rather than one big annual count. A cycle count approach (checking a small rotating subset of your materials each week) catches problems while they’re still manageable. QR code labels on your material bins can make these faster, scan to record a count rather than manually looking up each ingredient.

For the full picture on keeping raw material counts accurate: raw materials inventory management.

How Stocksmith helps you track shrinkage

Manual record-keeping rarely catches shrinkage as it happens. You have to be in the right headspace, remember to log the loss, and do it at exactly the right moment, which doesn’t happen when you’re mid-production and covered in soap batter.

Stocksmith connects your materials to your manufacturing records automatically. When you complete a manufacture, material stock levels update by the quantities the recipe actually consumed. When a batch fails, you record the run with what it used and what it produced, and the materials come off your inventory either way. When a stocktake reveals a discrepancy, the correction is recorded against the count, so there’s a dated trail rather than a silent edit.

That’s why it’s worth putting your true, real-world quantities into each product recipe rather than the idealised ones: every manufacture then accounts for the waste you genuinely generate, which keeps your COGS accurate and your pricing grounded in what production actually costs.

Over time, the data tells you something about your process: which products generate the most waste, whether certain seasons mean more spoilage, where the measurement errors tend to cluster. That’s hard to see in a spreadsheet, it usually only becomes visible after a painful tax-time reconciliation.

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