Beekeeping Reorder-Point Inventory Lab (2D)

Demand & Ordering

Weekly demand 20 jars/wk

Order quantity (Q) 120 jars

Supplier lead time 10 d

Reorder point (R) 60 jars

Live Readout

Stock on hand

0 jars

Days of cover

0.0 d

Cumulative stockout

0.0 d

Orders placed

Avg. stock held

0 jars

Service level

100.0%

How it works

This is a classic (Q, R) reorder-point inventory model. Stock drains continuously at the weekly demand rate. Whenever it falls to the reorder point R — and no order is already outstanding — a fixed order of size Q is placed automatically:

demand/day = demand/week ÷ 7
stock(t+dt) = stock(t) − demand/day · dt
if stock ≤ R and no order outstanding:
    place order, arrives at t + leadTime
on arrival:  stock += Q

If demand is fast and lead time long relative to R, stock can hit zero before the delivery arrives — a stockout, shaded red on the chart and tallied in the readout. A larger R buys more safety margin against demand variability and slow deliveries, at the cost of holding more cash in jars on the shelf. Service level is the fraction of simulated time stock was available (1 − stockout days ⁄ elapsed days).

Amber line — stock on hand over time.
Dashed line — reorder point R.
Orange tick — order placed; green tick — order arrives.
Red band — stock at zero (stockout).

Stock on hand Stockout Order arrives