Free Inventory Planning Template
A pre-wired per-SKU planner that auto-computes safety stock, reorder point, EOQ, and days of cover from your inputs. The same formulas the Lumina calculators use — all in one spreadsheet.
Drop your email to download. Opens in Excel, Google Sheets, or Numbers.
Sample populated view of the template
What’s inside the template
The maths every planner runs in a spreadsheet, pre-wired. Edit the inputs; the outputs recalculate live.
14-row per-SKU planner
Inputs: lead time, σ, daily demand, σ, order cost, holding cost, MOQ, current stock. Three pre-filled examples to show the shape.
Auto-computed columns
Annual demand, safety stock, reorder point, EOQ, and days of cover — all recalculate live as you edit the inputs.
Full-formula safety stock + EOQ
Uses the same Z × √((LT × σD²) + (D² × σLT²)) safety-stock formula and √((2 × D × S) / H) EOQ formula the Lumina calculators use.
Summary, alert rules, and tips
Total annual demand, SKU count, alert thresholds (REORDER NOW / soon / OK), a full column guide, and practitioner tips built into the file.
How to use the template
Six steps from download to a planning conversation. The formulas do the maths so you can’t fat-finger a safety stock under pressure.
- 1
Download the template
Drop your email, the file downloads immediately. Opens cleanly in Excel, Google Sheets, and Apple Numbers.
- 2
Confirm the global service-level Z
Cell B7 sets your target service level. The default is 1.645 (95%). Change it to 1.282 for 90% or 2.326 for 99%. Every safety-stock figure on the sheet recalculates against this single number.
- 3
Add a row per SKU
Fill in the input columns: SKU code, description, supplier, lead time (days), lead-time σ, average daily demand, daily demand σ, order cost, holding cost per unit per year, MOQ, and current stock. Three worked examples are pre-filled to show the shape.
- 4
Read the auto-computed columns
Annual demand, safety stock, reorder point, EOQ, and days of cover all recalculate live. The maths is the same Z × √((LT × σD²) + (D² × σLT²)) safety-stock formula and √((2 × D × S) / H) EOQ formula the Lumina calculators use.
- 5
Sort by days of cover to find the urgent SKUs
Sort the per-SKU plan by column P (days of cover) ascending — the SKUs at the top are the ones closest to running out. If days of cover is below the lead time σ, the safety stock is too thin and that SKU is one bad week away from a stockout.
- 6
Recompute quarterly
Demand drifts with seasonality and channel mix; lead times drift with supplier capacity. A plan computed in Q1 is rarely the right plan by Q3. Re-pull inputs and recompute at least once per quarter.
Why every scaling brand should have a per-SKU plan
An inventory plan is the document that turns a forecast into a buy. Without it, replenishment becomes a weekly improvisation against intuition, and the inevitable £50k mistake — a stocked-out hero SKU or an overstocked slow mover — happens about once a year for most brands. With it, the maths is auditable: who decided the buffer, what service level was assumed, what supplier inputs went into the EOQ.
The cost of holding a plan in a spreadsheet (this one) is roughly zero. The cost of not having one is one-bad-quarter per year. For scaling brands at £5–30M, the ROI on having any plan at all is asymmetric — and far more useful than the absence of one is widely admitted.
For the deeper formulas, see the safety stock calculator, EOQ calculator, and reorder point calculator. For the underlying concepts, see the glossary entries for safety stock, reorder point, lead time, and lead-time variability.
Frequently asked questions
What's in the inventory planning template?+
A pre-wired single-sheet planner with 14 SKU rows. You enter inputs (lead time, demand, σ, order cost, holding cost, MOQ, current stock); the template auto-computes annual demand, safety stock, reorder point, EOQ, and days of cover for each SKU. Three example SKUs are pre-filled to show the shape, plus a summary block, alert rules, a column guide, and tips. Opens cleanly in Excel, Sheets, and Numbers.
What's the safety stock formula it uses?+
The full formula: Safety Stock = Z × √((LT × σD²) + (D² × σLT²)). Z is the service-level multiplier (set globally in cell B7), σD is daily demand variability, D is daily demand, LT is average lead time in days, and σLT is lead-time variability in days. Setting σLT to 0 reverts to the simpler Z × σD × √LT version — the template handles both automatically.
What's the EOQ formula it uses?+
The textbook formula: EOQ = √((2 × D × S) / H). D is annual demand (auto-computed from daily demand × 365), S is order cost per PO, H is holding cost per unit per year. The result is the order quantity that minimises the sum of ordering and holding cost across the year.
How many SKUs does the template handle?+
Fourteen rows are pre-wired. To extend it: in Excel or Sheets, select the formula row 25 (the last pre-wired row) and drag-fill the formula cells down to add as many SKUs as you need. The maths is per-row, so there's no upper limit beyond the spreadsheet's own.
Can I change the service level for a single SKU?+
The global default is set in cell B7 (1.645 = 95%). For a single SKU, replace the $B$7 reference in that row's column M formula with the Z you want for that SKU. Common values: 1.282 (90%), 1.645 (95%), 2.054 (98%), 2.326 (99%). Top-seller SKUs typically run 98–99%; tail SKUs run 90–95%.
What if my MOQ is higher than my EOQ?+
Two interpretations. Either the order cost (column H) you entered is too low, or the holding cost (column I) is too high, or the supplier MOQ is forcing you into uneconomic batch sizes. The third is common with offshore manufacturers. Use the EOQ vs MOQ gap as a negotiation lever, not as a problem to live with — a supplier holding you to 5× EOQ is asking you to finance their production planning.
What's a sensible holding cost (column I)?+
Rule of thumb: 20–30% of the unit cost per year. Components: cost of capital (10–15%), warehousing and handling (5–10%), insurance (1%), obsolescence and shrinkage (2–5%, much higher for fashion or perishables). If you have your real numbers — finance can usually pull them — use those. If not, 25% of landed unit cost is the safest default.
When does the template stop being enough?+
When you have more than ~100 SKUs, when the SKUs sell across multiple channels with different demand patterns, when you need scenario planning, or when cash flow is driving PO timing as much as stock-on-hand. At that point the single-sheet model becomes the bottleneck, and a planning tool that runs the same maths continuously across the catalogue — like Lumina — pays for itself within a quarter.