What Is Days of Inventory on Hand?
Days of inventory on hand (DOH) estimates how many days your current stock can support sales at the current rate. It helps Shopify merchants spot stockout risk, plan reorder timing, and see how much cash is tied up in unsold products.
DOH is also called days sales of inventory (DSI). It is a snapshot based on average sales: a promotion, seasonal spike, or supply delay can change how long your stock lasts. Compare it with supplier lead time and test faster sales velocity before deciding when to reorder.
Days of Inventory on Hand Formulas
Value-based DOH
DOH = Current Inventory Value ÷ Average Daily COGS
Unit-based DOH
DOH = Current Units on Hand ÷ Average Units Sold per Day
Cash conversion cycle (CCC)
CCC = DSI + DSO − DPO
DSI is days of inventory on hand, DSO is the average days it takes to collect customer payments, and DPO is the number of days before you pay suppliers. For a DTC store, customer payments often arrive quickly, but supplier terms can still determine how long cash stays tied up.
To calculate daily COGS from a longer period, divide monthly COGS by 30 or annual COGS by 365. Use inventory value at cost, not retail price; the IRS explains how inventory costs are treated for tax accounting in its inventory accounting guidance.
How to Use This Calculator
- Enter Current Inventory — the total cost value of the inventory you have on hand.
- Enter Daily COGS — your average daily cost of goods sold. Divide monthly or annual COGS by the corresponding number of days if you do not track it daily.
- Enter Avg Daily Units and Current Units — use average units sold per day and the number of sellable units currently in stock to calculate unit-based coverage.
- Enter Unit Cost — the product’s cost to you, excluding its retail selling price.
- Enter Lead Time Days — the time from placing a supplier order until stock is available to sell. Compare this with DOH to identify whether current stock covers the wait.
- Enter Payment Terms Days and Receivables Days — use your supplier’s payment terms and the average time to receive customer payments. These inputs estimate CCC.
- Enter Holding Cost Pct and Selling Price — use your annual inventory carrying-cost rate and average selling price to assess the cost of holding stock and its relationship to sales.
Review DOH and lead-time coverage together: inventory can appear adequate at average sales velocity but run short if demand rises before the next shipment arrives.
Step-by-Step Example
A Shopify store has 2,400 reusable water bottles in stock. Each costs $15, average daily sales are 80 bottles, supplier lead time is 24 days, supplier terms are Net 20, and customer payments take 3 days to clear.
| Calculation | Arithmetic | Result |
|---|---|---|
| Inventory value | 2,400 × $15 | $36,000 |
| Daily COGS | 80 × $15 | $1,200 |
| Unit-based DOH | 2,400 ÷ 80 | 30 days |
| Value-based DOH | $36,000 ÷ $1,200 | 30 days |
| Lead-time coverage after arrival wait | 30 − 24 | 6 days |
| Cash conversion cycle | 30 + 3 − 20 | 13 days |
At the current rate, the store has six days of stock beyond the supplier’s lead time, before allowing for safety stock or fulfillment delays. If sales velocity rises by 25%, daily sales become 80 × 1.25 = 100 bottles, and coverage falls to 2,400 ÷ 100 = 24 days—equal to the lead time, leaving no buffer.
How to Interpret DOH and Lead-Time Coverage
DOH below lead time signals a potential stockout before replenishment arrives. A positive difference between DOH and lead time gives you a basic buffer, but it does not account for demand variability, order processing, receiving, or delays in making stock available.
A useful starting rule is to hold enough stock for the lead time plus a buffer of one to two weeks. Adjust that buffer for supplier reliability and demand swings: predictable products with dependable suppliers may need less, while seasonal or volatile products may need more. Use the Reorder Point Calculator to estimate a reorder trigger and safety stock based on demand and service level.
CCC adds payment timing to the inventory picture. A shorter or negative CCC means customer cash arrives before supplier bills are due; a longer CCC means more working capital stays committed to operations. The U.S. Census Bureau publishes retail sales and inventory data that can help merchants understand broader retail trends, but aggregate figures are not a substitute for your store’s SKU-level demand history (Census retail trade data).
Inventory Planning Benchmarks
There is no single DOH target that fits every store: product shelf life, supplier lead time, and demand uncertainty all change the amount of stock to carry. Use the following as planning comparisons, not universal industry averages.
| Product or supply situation | Planning benchmark |
|---|---|
| Perishable or short-shelf-life goods | Keep coverage close to the replenishment cycle; prioritize freshness and sell-through. |
| Stable, locally sourced products | Match coverage to lead time, then add a modest buffer based on supplier reliability. |
| Imported or custom-made products | Plan for longer replenishment cycles and test delayed-shipment scenarios. |
| Seasonal or promotion-driven products | Calculate coverage at expected peak velocity, not only at the annual average. |
For an additional comparison, the Census Bureau’s inventory-to-sales data tracks retail inventory relative to sales across the sector. It can show broad changes in retail stocking, but it does not set a target for an individual Shopify store.
6 Ways to Improve Inventory Coverage
- Test a demand spike: Change average daily unit sales from 40 to 52 in the calculator and check whether DOH still exceeds supplier lead time.
- Request a shorter supplier lead time: If a supplier can cut delivery from 28 days to 21, recalculate the buffer you need before tying up cash in more stock.
- Compare smaller, more frequent orders: Ask a supplier to quote weekly replenishment against monthly bulk orders; compare freight and per-unit costs with the cash freed by carrying fewer units.
- Set reorder alerts by SKU: Use Shopify’s inventory tracking or an inventory app to flag products before they reach the reorder point, rather than relying on a store-wide average.
- Separate high-impact products: Use the ABC Inventory Analysis Tool to focus forecasting and supplier follow-up on the SKUs that contribute most to sales or inventory value.
- Test the cost of excess stock: Change annual holding cost from 18% to 30% and compare the carrying cost; the Inventory Carrying Cost Calculator can help break down storage, capital, and other costs.
Frequently Asked Questions
What is days of inventory on hand (DOH)?
Days of inventory on hand (DOH) measures how many days your current inventory will last at the current sales rate. Formula: DOH = Current Inventory ÷ Daily COGS (or Current Units ÷ Daily Units Sold). If you have 3,200 units and sell 65/day, you have 49 days of inventory. DOH helps you know when to reorder and whether you're carrying too much or too little stock.
What is a good number of days of inventory on hand?
The ideal DOH depends on your lead time. A good rule: DOH should equal your lead time + 1-2 weeks buffer. With a 14-day lead time, aim for 21-42 days. Under lead time means you risk stockouts before the next order arrives. Over 2× lead time means too much capital tied up. Fast-fashion brands aim for 30-45 days, electronics 45-60 days, and luxury goods may carry 90+ days.
What is the cash conversion cycle?
The cash conversion cycle (CCC) measures how long cash is tied up in operations. Formula: CCC = DSI + DSO - DPO (Days Sales Inventory + Days Sales Outstanding - Days Payable Outstanding). For DTC e-commerce: DSI is your inventory days, DSO is ~0-3 days (instant payment), DPO is your supplier payment terms. A negative CCC means you collect from customers before paying suppliers — the ideal scenario.
How does sales velocity affect days on hand?
Sales velocity directly determines how fast inventory depletes. If velocity increases 50% (e.g., during a sale or viral moment), your 49-day inventory becomes 33 days. This is critical for planning: always check whether current DOH covers your lead time at peak velocity, not just average. The sensitivity table in this calculator shows DOH at different velocity levels so you can plan for demand spikes.
How do I reduce days of inventory on hand?
Five strategies: 1) Order smaller quantities more frequently. 2) Negotiate shorter lead times to reduce needed buffer. 3) Improve demand forecasting to order closer to actual need. 4) Run promotions to accelerate slow-moving inventory. 5) Drop-ship slow sellers to eliminate carrying inventory entirely. Reducing DOH frees up cash — going from 60 to 40 days on $48K inventory frees $16K in working capital.
About This Calculator
The Days of Inventory on Hand Calculator was built by Luis Dev Studio for Shopify merchants to compare inventory coverage, lead time, and cash timing. For help applying inventory tools to your store, contact us.
Updated by Luis Gonzalez · Jan 6, 2026