Shopify inventory management is the operational discipline of keeping the right products in stock, in the right quantities, at the right cost — and getting rid of the ones that aren't paying back. Restock alerts are the most visible piece, but the full loop also includes reorder-point math, ABC classification, dead-stock identification, and supplier coordination.
This article is the full inventory operations playbook for stores doing $10K–$500K/month, with the math, the dashboard, and the specific failure modes that drain cash.
ABC classification: where to spend your attention
Pareto in inventory: 20% of SKUs drive 80% of revenue. The math:
- A items: top 20% of SKUs by 30-day revenue. ~80% of total revenue. Tight inventory management; never stock out.
- B items: next 30% of SKUs. ~15% of revenue. Standard inventory management; occasional stockouts acceptable.
- C items: bottom 50% of SKUs. ~5% of revenue. Loose inventory management; let them go to zero before reordering.
The implication: spend 80% of your inventory time on the top 20% of SKUs. Most merchants spread attention evenly — half the catalog is undermanaged on the top end and overmanaged on the bottom.
Compute monthly. Recompute when seasonality shifts the rankings. DropifyXL's Restock recommendation prioritizes A items automatically.
Reorder point math (full version)
The classical formula:
reorder_point = (avg_daily_demand × lead_time_days) + safety_stock
Where:
avg_daily_demand=units_sold_last_30d / 30(or weighted: 70% weight on last 7 days, 30% on previous 23, to capture trend).lead_time_days= honest supplier-to-warehouse window. Use worse-than-average, not best-case.safety_stock=Z × σ × √lead_timewhere Z is the service-level constant (1.65 for 95%, 2.33 for 99%), and σ is the standard deviation of daily demand.
For most small Shopify merchants, the rigorous safety-stock formula is overkill. Approximation: safety stock = 50% of lead-time demand for A items, 25% for B, 0% for C.
Worked example: top SKU sells 8 units/day, supplier lead time 10 days. Lead-time demand = 80 units. Safety stock at 50% = 40 units. Reorder point = 120. When inventory drops to 120, reorder.
Dead stock: identifying and liquidating
A SKU sitting on the shelf for 90+ days with negligible sales is dead stock. Cost: warehouse space, capital tied up, eventual write-off.
Identify dead stock with two cuts:
- No sales in last 90 days, despite ≥30 days inventory available. Slow-mover, but not necessarily dead.
- Less than 1 sale per month sustained for 180 days. Dead.
Liquidation options, in order of preference:
- Bundle with a fast-mover. Sell the dead SKU paired with a winner at a small discount. Customers get value; you clear the bad inventory.
- Cross-sell on cart. Offer dead stock at 30% off as a cart add-on at checkout.
- Free with purchase over $X. Use as a "free gift" threshold incentive (see pricing psychology).
- Markdown on a sale event. Black Friday, end-of-season clearance.
- Donate or write off. When all else fails. Take the tax loss; recover the warehouse space.
Avoid: marking down dead stock 50%+ on a normal day. Trains customers to wait for discounts on living SKUs.
Supplier-side metrics
Most inventory failures originate upstream. Track these per-supplier:
- Lead time variance: average lead time vs worst-case lead time. Suppliers with high variance break your reorder math.
- Order fulfillment rate: percent of POs delivered complete vs short.
- Quality rejection rate: percent of received units rejected (damaged, wrong, defective).
- Communication response time: how long to confirm an order, ETA, or issue resolution.
A supplier with 14-day average lead time and 21-day worst-case is materially worse than one with 14-day average and 16-day worst-case. The variance is the cost.
If you have one supplier per category, you have a single point of failure. Aim for 2 qualified suppliers for any A-item category — even if you give 80% to the primary, the backup means you're not held hostage.
See the supplier management guide for the full playbook.
The weekly inventory dashboard
What to look at every Monday morning (5 minutes):
| Metric | Watch when |
|---|---|
| A-item SKUs at <14 days cover | Any. Trigger reorder. |
| B-item SKUs at <7 days cover | Any. Trigger reorder. |
| Total inventory value | If growing >5% month-over-month, audit: are you over-buying? |
| Dead-stock count (90d no sales) | Trigger liquidation campaign if >5% of SKU count. |
| Open POs (PO sent, not received) | Track aging; flag any past expected-delivery date. |
| Supplier short-shipments this week | If non-zero, expedite communication. |
Most of this lives in your Shopify Admin or in a connected inventory tool. DropifyXL surfaces the A-item restock recommendations directly in the weekly action plan.
Common failure modes
Over-buying A items "just in case"
A 90-day inventory cushion on a fast-mover ties up cash you need for ad spend or new product testing. The right cushion is lead_time × 1.5, not 6 months of sales.
Under-buying A items "to save cash"
A 5-day cushion on a top-3 SKU means a stockout when supplier slips by 2 days. Cost of a stockout outweighs the cash savings.
Treating B and C items like A items
Auditing every SKU's days-of-cover weekly is wasted attention. Set lower thresholds and longer review cadences for B and C.
No visibility into in-transit inventory
A PO placed but not received doesn't show in "available inventory" in most systems. Easy to over-order if you don't track in-transit separately.
Ignoring seasonality
A 30-day rolling average undershoots seasonal peaks (December, summer beach gear) until they're already happening. Use longer windows (90-day rolling) plus year-over-year comparison for seasonal categories.
Tools
What you actually need:
- Shopify Admin: built-in inventory tracking, basic stock alerts. Adequate up to ~$100K/month with 200 SKUs.
- DropifyXL: surfaces A-item restock alerts in your weekly action plan. $19/mo.
- Inventory Planner / StockTrim ($120–$300/mo): full reorder-point automation, multi-location, demand forecasting. Worth it at $200K+/month or 500+ SKUs.
- Spreadsheet (the intermediate option): pull Shopify data via API or Sheetgo, run the math yourself. Cheap; brittle past 100 SKUs.
Don't over-buy tooling. Most stores under $100K/month do fine on Shopify Admin + DropifyXL. The expensive tools earn their keep at scale.
Frequently asked questions
What's a healthy days-of-cover for a Shopify store?
Depends on supplier lead time. For dropshippers with 14-day suppliers: target 21–28 days of cover on A items. For in-region warehouses with 3-day reorders: 5–7 days. Set thresholds per supplier, not globally.
How do I forecast demand for a new product?
You can't, with confidence. Order conservatively for the first 60 days (initial ~30 days of expected demand based on launch hypothesis). Reorder aggressively when 14-day sell-through confirms demand. Avoid the "let's order 6 months of inventory" temptation on new products.
What's the right ABC threshold?
Top 20% by 30-day revenue = A. Next 30% = B. Bottom 50% = C. Adjust the percentage if your catalog is unusually concentrated (a 5-SKU store has different math than a 500-SKU store).
How often should I do a physical inventory count?
For dropshipping: rarely (your supplier holds physical inventory). For self-fulfilled: monthly cycle counts on A items, quarterly full counts on B/C. Discrepancies between Shopify-reported and physical inventory of >2% suggest process issues.
Does DropifyXL handle full inventory management?
DropifyXL surfaces recommendations for the most leveraged inventory actions (restock, slow-mover liquidation candidates). For full inventory ops (multi-location, forecasting, PO management), pair with Inventory Planner or similar at scale. DropifyXL is the what to do this week; the inventory tool is the operational system.
Key takeaways
- ABC classification: 80% of inventory attention on the top 20% of SKUs.
- Reorder point =
(avg_daily_demand × lead_time) + safety_stock. Safety stock = 50% of lead-time demand for A items. - Identify and liquidate dead stock quarterly. 90 days no sales + ≥30 days inventory = liquidate.
- Track per-supplier: lead time variance, fulfillment rate, quality rejection rate.
- Weekly dashboard: A items at <14 days, B at <7 days, dead-stock count, open POs.
Inventory is the slowest-moving lever in your store. Get it right and it disappears as a problem; get it wrong and it dominates your week.
