Reorder Point & EOQ
When to reorder and how much, per item: reorder point from daily demand, lead time and your safety stock; economic order quantity from order and holding cost.
A reorder point and order quantity for every item on the list, with orders per year, cycle length and the ordering-versus-holding cost balance, and which items to order today.
Example: 40 a day with a 12-day lead time and 100 safety stock → reorder at 580; 14,600 a year at 50 per order and 2.40 to hold a unit a year → EOQ 780, about 19 orders a year every 19.5 days.
When to order is one sum;
how much is another.
The reorder-point rule, the economic order quantity and what it assumes, and why safety stock is left to you.
Reorder point
The reorder point is the stock level at which a new order must be placed so that it arrives before you run out: average daily demand × lead time in days, plus safety stock. Safety stock is the buffer for demand above average and deliveries later than promised; how much you want depends on how variable both are and how costly a stock-out is, so it is an input here, not a formula — and the page notes when it is zero. With stock on hand entered, each item shows its cover above the reorder point (negative means order now) and days of stock at the average rate.
Economic order quantity
EOQ balances two costs that pull in opposite directions: ordering more often costs more in fixed order costs (S per order), holding more stock costs more in capital, space and shrinkage (H per unit per year). Total cost is lowest where the two are equal, which gives Harris's 1913 formula EOQ = √(2DS ÷ H) with D the annual demand (daily demand × the days per year you set). The page rounds the quantity up to whole units and reports orders per year, the cycle in days, and both annual costs at the optimum — they match, which is the check. The model assumes constant demand, a fixed cost per order and a linear holding cost; it ignores quantity discounts, minimum order quantities and pack sizes.
What the tool does not decide
Your holding-cost rate, your order cost, your service level and therefore your safety stock; seasonal or trending demand; supplier minimums and pack sizes (round the EOQ to them yourself); and whether one item's order should be combined with another's to reach a freight threshold. Nothing you enter leaves the browser; the same four anonymous usage counts as the rest of the site apply.
SOURCES
- F. W. Harris, "How Many Parts to Make at Once", Factory, The Magazine of Management 10(2), 1913 — the economic order quantity formula
Last reviewed 19 September 2026. How results are checked: How we verify.