5 Inventory Metrics Every Shopify Brand Should Track Daily
You check your revenue every day. You check your ad performance every day. You probably check your social media every day.
But when was the last time you checked your inventory health? If the answer is "last week" or "when something went wrong," you are managing one of your largest assets on autopilot.
Inventory is typically the biggest line item on a D2C brand's balance sheet. For many Shopify brands, it represents 30-50% of total assets. Yet the sophistication applied to managing it is nowhere near what gets applied to marketing or customer acquisition.
Here are five metrics that change that. Track them daily. React to the red flags immediately. Your margins will thank you.
1. Days of Stock (DOS)
What it is: The number of days your current inventory will last at the current sales velocity.
Formula:
Days of Stock = Current Inventory Units / Average Daily Sales (last 14 days)Why it matters: Days of Stock is the single most important leading indicator in inventory management. It tells you when you will run out. Not approximately. Precisely.
Revenue tells you what happened yesterday. DOS tells you what will happen next week.
How to use it:
- Below 7 days: Red alert. If your reorder lead time is longer than 7 days, you are already going to stock out. Immediately check if you can expedite a reorder or reduce ad spend on that SKU to slow velocity.
- 7-21 days: Yellow zone. Place your reorder now if you have not already. Factor in lead time from your supplier.
- 21-60 days: Green. Healthy runway. Check weekly.
- Above 90 days: Orange. You may be overstocked. Consider running a promotion or bundling this product to accelerate sell-through.
Red flags: DOS trending down week over week on a hero product. DOS spiking up suddenly (which means sales velocity dropped, often indicating a demand problem).
2. Sell-Through Rate
What it is: The percentage of inventory received that has been sold within a specific period.
Formula:
Sell-Through Rate = Units Sold / (Units Sold + Units in Stock) x 100Calculate this over a consistent period, typically 30 days or since the last restock.
Why it matters: Sell-through rate tells you how efficiently your capital is converting into revenue. A product with a low sell-through rate is tying up cash that could be deployed elsewhere.
Benchmarks:
| Sell-Through Rate | Interpretation |
|---|---|
| Above 80% | Excellent. But watch for stockouts. |
| 60-80% | Healthy. Demand matches supply well. |
| 40-60% | Moderate. Review pricing or marketing support. |
| Below 40% | Concerning. This product may need a promotion, price cut, or discontinuation. |
Red flags: Sell-through dropping month over month. New product launches with sell-through below 30% after 60 days, which signals a demand forecasting miss.
3. Stock-to-Sales Ratio
What it is: The ratio of inventory value to sales value over a given period. It is the inverse perspective of sell-through.
Formula:
Stock-to-Sales Ratio = Inventory Value at Cost / Net Sales Value (30 days)Why it matters: This ratio connects your inventory directly to your cash flow. A high stock-to-sales ratio means you have more cash locked in shelves than flowing through revenue. For cash-constrained D2C brands, this is the metric that determines whether you can afford your next ad campaign or product launch.
Benchmarks:
- Below 2.0: Efficient. Your inventory is turning quickly.
- 2.0-4.0: Normal for most D2C categories.
- 4.0-6.0: Heavy. Review which SKUs are dragging the ratio up.
- Above 6.0: Critical. You have a dead stock problem.
Red flags: Ratio increasing quarter over quarter while revenue stays flat. This means you are buying more inventory without selling more, a classic margin trap.
4. Reorder Point
What it is: The inventory level at which you should place a new order to avoid a stockout, accounting for lead time.
Formula:
Reorder Point = (Average Daily Sales x Lead Time in Days) + Safety StockWhere Safety Stock accounts for variability:
Safety Stock = (Max Daily Sales - Average Daily Sales) x Lead TimeWhy it matters: The reorder point is the difference between proactive and reactive inventory management. Without it, you are guessing when to reorder. With it, you have a precise trigger.
Example: Your best-selling product averages 10 units/day. Your supplier lead time is 14 days. Your peak daily sales hit 15 units.
- Reorder Point = (10 x 14) + ((15 - 10) x 14) = 140 + 70 = 210 units
- When your inventory hits 210 units, place the order. Below that, you risk a stockout during the lead time window.
Red flags: Current inventory already below your reorder point (you are late). Lead times increasing from your supplier without adjusting your reorder points accordingly.
5. Dead Stock Percentage
What it is: The percentage of your total inventory that has not sold in 90 days or more.
Formula:
Dead Stock % = (Value of Inventory with Zero Sales in 90+ Days / Total Inventory Value) x 100Why it matters: Dead stock is not just unsold product. It is cash that is permanently trapped. It is warehouse space that costs rent. It is product that is aging, and in categories like food, supplements, or skincare, it may expire.
Most D2C brands do not calculate this number because the answer is uncomfortable. Industry data suggests the average brand carries 20-30% dead stock.
Benchmarks:
| Dead Stock % | Interpretation |
|---|---|
| Below 5% | Excellent inventory management. |
| 5-15% | Normal. Review quarterly and liquidate strategically. |
| 15-25% | High. Significant capital is trapped. Immediate action needed. |
| Above 25% | Critical. Your buying process needs a fundamental overhaul. |
Red flags: Dead stock percentage increasing quarter over quarter. Any hero product entering the dead stock category, as this signals a market shift you need to investigate.
Why Daily Tracking Matters
These metrics are not monthly review items. They are daily operational signals.
A product can go from "healthy" to "stockout imminent" in 5 days if a campaign goes viral or a competitor runs out. A slow-moving SKU can tip from "moderate" to "dead stock" in a single quarter.
Daily tracking does not mean daily panic. It means daily awareness. You check your revenue daily because you want to know if something changed. Apply the same discipline to inventory.
The Problem with Manual Tracking
The formulas above are straightforward. The challenge is computing them daily across every SKU, accounting for sales velocity changes, lead time variations, and seasonal patterns.
Most brands default to checking inventory when something goes wrong: a customer complains about an out-of-stock item, an ad campaign is driving traffic to a product with 3 days of runway, or the warehouse sends an alert about expiring product.
By then, the damage is done. You have already lost the sales, wasted the ad spend, or written off the inventory.
Automating Inventory Intelligence
Nucks connects to your Shopify store and computes all five metrics automatically, every day, for every SKU. When a product crosses a threshold, you know immediately rather than at your next manual check.
More importantly, Nucks correlates inventory data with your ad spend. When a hero product hits 7 days of stock, it does not just alert you. It can suggest reducing ad spend on that product to slow velocity, preventing a stockout while you wait for your reorder.
That cross-platform intelligence, connecting inventory data with ad campaign data, is something no spreadsheet can do in real time.
Your inventory is your biggest asset. Start treating it like one.