A lender, a buyer or a new board member asks about 3 numbers the monthly pack does not carry.
Your monthly pack shows inventory value, turns and days on hand. Then the bank, a buyer in diligence or a new board member asks a question those 3 numbers cannot answer, and the reply starts with “let me get back to you.”
I have seen this in auto parts, in food manufacturing and in pet toys. It is the same in a long list of quiet businesses nobody writes about. They make good money, and a lot of that money sits on a shelf. Below are the 3 inventory KPIs a CFO should add to the pack, and 24 businesses where each one hides. Find yours.
Why the pack never shows them
A monthly pack is built from what the system already totals: value at cost, cost of sales, units on hand. Each of the 3 numbers below needs something the system does not total on its own. The first needs the list of reconciling items next to the ledger. The second needs the last sale date of every item, multiplied by its value. The third needs last year's forecast kept and set against what actually sold.
None of that is hard. It is simply nobody's job. So the pack reports the averages, and the averages look fine.
1. Unexplained Difference: what is left after the inventory reconciliation
Stock report to ledger difference - sum of named reconciling items
Example: the stock report says $1,000,000 and the ledger says $1,012,000. You can name $8,000 of goods in transit and $2,500 of receipts not yet invoiced. The Unexplained Difference is $1,500, and that is the number to chase.
What it catches: the part of the inventory balance nobody can defend. Most teams compare 2 totals and post an adjustment when the gap is small. This asks the harder question: after every item you can name, what is left?
Hover over, or tap, any business name to see why the gap appears there.
Where it hides:
- Auto parts distributorsA core is the old part a customer returns for credit, like a used alternator. It sits in the warehouse before the supplier's credit arrives, so the shelf and the books disagree in between.: cores and warranty returns sitting between the shelf and the credit note
- Welding gas and supplyThe gas supplier owns the cylinders and rents them to customers. If cylinders at customer sites are still in the stock count, the books show stock that is not in the building.: cylinders out at customers on deposit, still counted as stock
- Medical device distributorsConsigned kits sit at the hospital but belong to the distributor until a surgeon uses one. Nobody counts them in between, so missing or expired kits surface months later.: consigned kits in hospital supply rooms, billed only when used, counted by nobody between visits
- Lumber and building materialsThe mill ships straight to the customer's site and bills the distributor. If nobody enters the receipt, the bill reaches the books with no matching stock movement.: loads shipped straight to the job site, billed by the mill, never received into the yard
- Frozen seafood importersNo 2 cases of fish weigh exactly the same. Bought and billed by the pound but tracked by the case, value and quantity drift apart a little on every delivery.: bought and invoiced by weight, stocked and counted by the case, so the 2 never quite agree
- Lubricant and fuel distributorsFuel and oil expand when warm and shrink when cold. A tank dipped on a hot afternoon shows more gallons than the same tank on a cold morning, so the count and the books drift apart unless every reading is corrected for temperature.: tanks measured with a dipstick, where the volume moves with the temperature, so book gallons and real gallons never quite match
- Fabric and textile distributorsThe system tracks fabric by the metre, so it takes the 13 metres off as if both cuts came from one roll, and still shows a full 50-metre roll ready to sell. On the shelf there are 2 partial rolls of 47 and 40 metres. When an order needs a full roll, there is none.: 3 metres cut from one roll and 10 from another: the system shows 1 full roll and 1 partial, the shelf holds 2 partial rolls
- Electronics and accessories importersOn many shipping terms the importer owns the goods once they leave the overseas port. They belong in inventory while still at sea, but are often recorded only on arrival.: containers on the water, owned since they left the port and not yet in the system
Healthy: zero, every month. Red flag: any amount left over and posted as a plug.
2. Value-Weighted Stock Age: inventory aging measured in dollars
Sum of (item value at cost x days since last sale) / total inventory at cost
Example: item A holds $50,000 and last sold 300 days ago. Item B holds $10,000 and sold 20 days ago. Counted by item, the average age is 160 days. Weighted by value, it is 253 days, because most of the cash sits in the old item.
What it catches: how old the dollars are, not how many items are old. Days in inventory is an average. It looks steady while a few large, old items quietly hold the cash.
Where it hides:
- Pet toys and giftsHoliday lines are bought in large quantities months ahead. Whatever does not sell by December can sit for a year at full cost.: last year's holiday line, bought deep for one season
- Bearings and power transmissionA large industrial bearing can cost thousands of dollars. Stocked for one customer's machine, it stops selling the day that machine is replaced, and stays on the books at full value.: a large part stocked for one customer's machine, after the customer replaced the machine
- Tile and stone importersTile is made in batches whose colour varies slightly, and a customer cannot mix batches. So the last pallets of a discontinued colour rarely sell.: the last pallets of a discontinued colour that no new order can match
- Restaurant equipment partsParts for ovens and fryers no longer made are kept for service calls. Each part sells rarely, but each one holds real cash for years.: parts for ovens and fryers no longer made, kept in case someone calls
- Uniform and workwearGarments with a customer's logo can only be sold to that customer. When the customer leaves, the stock has no other buyer.: logo garments made for a customer who changed suppliers
- Marine partsEngine parts for models no longer made sell a few times a year, so they stay on the shelf at full cost.: parts for outboard engines out of production, sold twice a year
- Promotional productsPrinted products carry one customer's campaign. Cancel the campaign and the stock is worth little to anyone else.: printed stock for a campaign the customer cancelled
- Musical instrument distributorsOne high-end instrument can hold as much cash as hundreds of small accessories, so a few slow pieces push the average age up a lot.: high-end pieces that sell once a year and cost as much as a pallet of strings
Healthy: steady or falling against your own last 12 months. Red flag: age rising while days in inventory look stable.
3. Forecast Bias: the formula, and why it is not forecast accuracy
(Sum of forecast units - sum of actual units) / sum of actual units
Example: the forecast for the last 12 months was 1,150 units and 1,000 sold. Forecast Bias is +15%. The forecast ran high, so the purchase orders did too.
What it catches: which way the forecast leans. Accuracy tells you how far off you were. Bias tells you whether you are always off in the same direction. A forecast that runs high month after month buys cash into stock, one purchase order at a time.
Where it hides:
- Food manufacturingPromotions tend to be planned on the optimistic side. With a short shelf life, the extra product cannot wait for next month. It expires and is written off.: promotions planned high on product with a short shelf life, so the miss becomes a write-off
- Pool and spa supplyDemand follows the weather. Planning every season for the hottest summer leaves chemicals on the shelf through the winter.: every spring planned like the hottest one, with chemicals carried through the winter
- Seed and crop inputsDealers order early to get the supplier's discount, before farmers commit. Whatever is not sold comes back after the season.: early-order programs booked high, with returns arriving after the season
- HVAC partsAir-conditioning parts sell in heat waves. Planning every summer like the record one leaves stock behind when the summer is mild.: every summer planned like the record one
- Supplement contract manufacturersIngredients are bought for a client's launch forecast. If the launch is slower, the ingredients expire before they are used.: raw materials bought for a customer's launch, with a shelf life shorter than the launch
- Coffee importers and roastersGreen coffee is bought on contracts up to a year ahead. If the expected growth does not come, the beans sit and age.: green coffee bought a year ahead, on growth that has not arrived yet
- Spice and ingredient importersMany spices are harvested once a year, so a whole year's supply is bought at once. Last year's sales plus optimism becomes a year of extra stock.: a full year bought at harvest, on last year's sales plus a hope
- Veterinary supplyFlea and tick products sell in spring and summer. Stock bought for a long season can be close to its expiry date by the autumn.: flea and tick season planned long, with dated product left on the shelf in the autumn
Healthy: close to zero, with misses on both sides. Red flag: a steady positive bias.
What it cost one business
A medical consumables company booked an inventory adjustment every month for 2 years. About $20,000 in all. The books balanced. The accountant signed off. Nobody could say what the adjustment was.
The cause was 3 dates. The purchase order, the supplier invoice and the warehouse receipt each put the cost in a different month. Once the timing was aligned, the adjustment was gone. The Unexplained Difference would have flagged it in month 1: a gap left over after every named item, every month. Why the same adjustment keeps coming back walks through the pattern.
3 checks to run this week
- Unexplained Difference. Take last month's stock report and your ledger balance. List every reconciling item you can name and subtract them from the gap. Is what is left zero?
- Value-Weighted Stock Age. Sort the stock by value at cost x days since last sale. How much of the total sits in the top 20 items, and when did each of them last sell?
- Forecast Bias. Add up the last 12 months of forecast units and actual units for your top 50 items. Is the forecast higher in most of them?
If any answer surprises you, that is the number a lender or a buyer will find before you do.
Questions finance teams ask
What inventory KPIs should a CFO track?
Beyond inventory value, turns and days on hand, a CFO should track 3 numbers most monthly packs miss: the Unexplained Difference after the inventory reconciliation, Value-Weighted Stock Age, and Forecast Bias. These are the numbers a lender, a buyer or a board asks about first.
What is an acceptable inventory variance?
The gap between the stock report and the ledger can be any size, as long as every dollar of it is named: goods in transit, receipts not invoiced, returns not processed. The part nobody can name, the Unexplained Difference, should be zero every month.
How do you calculate forecast bias?
Forecast bias = (sum of forecast units - sum of actual units) / sum of actual units. A forecast of 1,150 units against 1,000 sold is a bias of +15%. A positive bias means the forecast runs high, which buys cash into stock.
What is the difference between forecast bias and forecast accuracy?
Forecast accuracy, often measured as MAPE, shows how big the misses are, whichever way they fall. Forecast bias keeps the direction, so it shows whether the misses lean one way. A forecast can be 90% accurate and still run high every month.
How do you calculate inventory aging in dollars?
Multiply each item's value at cost by its days since last sale, add the results, and divide by total inventory at cost. This Value-Weighted Stock Age shows how old the cash is, so a few large, old items cannot hide inside a normal average.
Which inventory KPIs does a lender look at?
A lender looks at the share of inventory the loan agreement counts as eligible, the stock it excludes as aged or slow, the reserve against slow stock, and the cash conversion cycle. Aged stock shrinks the line you can draw.
Keep the list
All 3 sit in the Inventory KPI Library with 97 more, sorted by the question each one answers: where the cash is stuck, whether the books agree, what the board should see. Each has the formula, what healthy looks like and the red flag, and all 100 come as one Excel sheet you can filter.
Open the Inventory KPI Library
The CFO who can defend every number in the room has these 3 in the pack before anyone asks.
Is this your number?
If your close balances and the number still moves, this is the work: a month-end figure that matches what actually happened.