Reorder at 224 units, not 120: in the worked example a supplier running 14 days instead of 10 while sales hit 16 a day leaves 104 units short — $1,612 of gross profit gone on one SKU.
Reorder at 224 units — you have 6.3 days. Ordering at 120 instead leaves 104 units short in a worst-case delivery: $1,612.00 of gross profit.
| Gross margin per unit | $15.50 |
| Units sold during a usual lead time (average × usual days) | 120 |
| Units sold during a worst-case lead time (busiest × slowest) | 224 |
| Safety stock (worst case minus usual) | 104 |
| Reorder point — order when stock falls to this | 224 |
| Days of stock left at average sales | 25 |
| Days until you reach the reorder point (0 = order today) | 6.3 |
| Order quantity if you order today (covers lead time + cycle + safety stock) | 284 |
| Cost of that order | $2,414.00 |
| Gross profit lost in a worst-case lead time without safety stock | $1,612.00 |
| Stock value at cost (for your year-end count) | $2,550.00 |
| Cash held in the safety buffer | $884.00 |
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Safety stock = (busiest day × slowest lead time) − (average day × usual lead time). Reorder point = average day × usual lead time + safety stock. Example: 12 a day on average, 16 on the busiest day, 10 days usual delivery, 14 days slowest → 120 + 104 = reorder at 224 units. A plain “average × lead time” reorder level of 120 runs 104 units short when the busy week and the late delivery land together — 104 × $15.50 margin = $1,612.
Stock value at cost is the number the IRS asks for on Schedule C (Form 1040) Part III line 41, “Inventory at end of year”. Count on 31 December, multiply by unit cost, add up every SKU. Corporations and partnerships use Form 1125-A. Yardstick: the median US logistician earns $39.58 an hour (BLS OEWS 2025, SOC 13-1081).
One-time Excel workbook (5 sheets): an SKU register with 100 rows that flags REORDER NOW for every product below its reorder point and totals the order cost across the catalogue, plus a Schedule C Part III year-end sheet (lines 35–42) that takes line 41 straight from your counted stock. One SKU answ
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An inventory planner does this job for pay: BLS OEWS 2025 puts the median US logistician (SOC 13-1081) at $39.58 an hour ($82,320 a year). The IRS asks for the same closing number on Schedule C Part III line 41, 'Inventory at end
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Real numbers from this tool, line by line.
A US small seller who moves 12 units a day and reorders at 120 units loses $1,612 of gross profit on one SKU the week the supplier is late and sales spike. Here is that example, worked out with the free inventory management template:
| Line | Example SKU |
|---|---|
| Average sales | 12 units a day |
| Busiest day | 16 units |
| Usual supplier lead time | 10 days |
| Slowest lead time seen | 14 days |
| Usual lead-time demand | 120 units |
| Worst-case lead-time demand | 224 units |
| Safety stock | 104 units |
| Reorder point | 224 units |
| Gross profit lost without safety stock | 104 × $15.50 = $1,612 |
If you order when stock falls to 120, you are covered only when everything goes to plan. When the busy week and the slow delivery land together, you sell 224 units before the new stock arrives. The 104 you did not have are sales that go to someone else.
Most free inventory list templates give you a column called "reorder level" and leave it empty for you to type a number. Others fill it with average daily sales times lead time. That number is the middle of the road. It assumes your supplier is never late and you never have a good week.
The template uses the max-min rule instead:
With the example numbers: 16 × 14 = 224, minus 12 × 10 = 120, gives 104 units of safety stock. The reorder point is 120 + 104 = 224 units.
You type eight numbers for one product: units on hand, average and busiest daily sales, usual and slowest lead time, unit cost, selling price and the days between your orders. The page returns:
A soy candle with 90 units on hand, 6 a day on average, 9 on the busiest day and a supplier who takes 12 to 18 days needs a reorder point of 162. It is already below that, so the answer is order today: 252 units for $1,058.40. Without the buffer it would lose $1,242.00 of gross profit.
A product with steady sales and a supplier who is always on time has no gap between usual and worst case. Safety stock drops to zero, the reorder point is 120 and you have 15 days before you need to order.
Stock value at cost is the figure the IRS asks for on Schedule C (Form 1040) Part III, line 41, "Inventory at end of year". Count on 31 December, multiply by unit cost and add up every SKU.
The browser calculator is free for one SKU, with all 12 results and nothing held back. The one-time Excel workbook adds a 100-row SKU Register that flags REORDER NOW across your whole catalogue, totals order cost and stock value, and a Year-End Count sheet that follows Schedule C Part III lines 35 to 42. For scale: the median US logistician earns $39.58 an hour (BLS OEWS 2025).
Try your best-selling SKU first. If the reorder point it gives you is higher than the one you use, that difference is your next stockout.
For each product it works out safety stock from your busiest sales day and slowest supplier, the reorder point, the days left before you must order, how many units to order and what that order costs. It also shows the gross profit a stockout would cost: in the worked example 104 units short × $15.50 margin = $1,612.
US small product businesses — online store owners, market sellers and small shops — who buy stock from suppliers with lead times of one to four weeks and file Schedule C Part III. If you have ever run out because a delivery came late, or overbought to be safe, this is the sheet that sets the line.
Most free inventory list templates leave the reorder level as a number you type in yourself, or use average sales × lead time with no safety stock. In the example that plain point is 120 units; covering the busiest day and slowest delivery needs 224. The gap is where stockouts come from.
The browser calculator is free and complete for one SKU: all 12 results, nothing hidden, no sign-up, your numbers stay on your device. The $21 one-time Excel workbook adds a 100-row SKU register that flags REORDER NOW across your whole catalogue and a Schedule C Part III year-end sheet.
Reorder planning is a logistician's job: BLS OEWS 2025 puts the median US logistician at $39.58 an hour. The workbook is a one-time $21, opens in Excel or Google Sheets (File ▸ Import ▸ Upload), and you re-use it every week with your own counts — no subscription.
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