Stockout Calculator: Days of Stock Left and When to Reorder
Free tool · Updated October 2, 2026 · By CouponTalk · Reviewed by CouponTalk Expert Reviews on
Your result
Enter your measurements to see your result.
Quick answer
Days of stock left = current stock ÷ daily sales. With 600 units selling 25 a day, you have 24 days. With a 12-day lead time and 100 units of safety stock, you must reorder within 8 days. Every day out of stock costs ₹3,000 in lost profit at ₹120 per unit, plus lost ranking.
How to use this calculator
- Enter stock on hand, including stock in marketplace warehouses.
- Enter average daily sales from the last 30 days.
- Add lead time and the safety stock you want to keep.
Formula
Days left = current stock ÷ daily sales
Reorder within = (stock − safety stock) ÷ daily sales − lead time
Daily sales change by season. Update the number before every reorder.
Frequently asked questions
What happens to ranking when I go out of stock?
On most marketplaces, listings lose sales history momentum and can drop in search, which takes time to recover.
How often should I check stock?
Weekly, and daily during sale events.
Can I avoid stockouts during big sales?
Send stock early and use the safety stock calculator with festive sales numbers.
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