Safety stock · days of cover · PO sizing · cash required

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//// Business · Inventory Ops

Inventory Reorder Point Calculator

Know when to reorder, how much to buy, and how much working capital the next purchase order will consume.

Where this fits

📈 Investing & Wealth Seller OS Trading Income Sellers Traders

This tool lives inside Seller OS + Trading Income and is most useful for sellers and traders.

Corp Tax Rate21%(federal flat rate)

SE Threshold$400(net earnings floor)

FICA Cap 2024$168,600(SS wage base)

Inventory Reorder Point Calculator — Know when to reorder, how much to buy, and how much cash the next PO will consume before stockouts start stealing profit.

Inventory Position

Units on handIncoming unitsAlready ordered but not receivedMonthly sales velocityUnits sold in a typical monthUnit costLanded or purchase cost

Supplier Timing

Lead time (days)Safety stock (days)Buffer against delays or demand spikesTarget coverage (days)Inventory you want after replenishment landsGrowth buffer %Seasonality or growth uplift

Reorder point

462.0 units

Inventory position where the next PO should trigger

Inventory cover

45.5 days

Current and incoming inventory runway

Order now?

Not yet

3.5 days until reorder point

Suggested PO

457.0 units

Sized for lead time, target coverage, and safety stock

Reorder investment

$3,998.75

Estimated cash needed for the next order

Growth-adjusted daily sales

11.00/day

Includes 10.0% buffer

Your inventory position is still healthy, but the reorder date is visible now. This is the moment to align sourcing, cash flow, and margin before the clock gets tight.

Seller Ops Playbook

The inventory win is staying in stock without drowning in dead cash.

This calculator helps sellers connect demand, lead times, and working capital so replenishment stops being reactive and starts feeling controlled.

What To Do Next

You have about 3.5 days before inventory reaches the reorder zone at the current pace.

A suggested reorder of 457.0 units would require about $3,998.75 of working capital.

Pressure-test the new order against margin and cash flow next so you do not fix stockouts by accidentally crushing profitability.

Reorder status

Healthy

Whether inventory has already fallen into the trigger zone.

Days of cover

45.5 days

How long current and incoming stock should last.

Suggested PO

457.0 units

Recommended order size to restore planned coverage.

Cash required

$3,998.75

Working capital needed for the next buy.

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Available inventory position

on_hand + incoming_units

420 + 80

= 500 units

Inventory planning should include both stock on hand and purchase orders already on the way.

Inventory position formula

Adjusted daily sales

(monthly_sales ÷ 30) × (1 + growth_buffer)

(300 ÷ 30) × (1 + 10.0%)

= 11.00 units/day

The growth buffer protects you from seasonal lifts or rising velocity instead of planning off the bare historical average.

Demand forecasting with growth-adjusted daily velocity

Lead-time demand

adjusted_daily_sales × lead_time_days

11.00 × 28

= 308.0 units

This is how many units you expect to sell while you wait for the next order to arrive.

Standard reorder-point lead-time demand formula

Safety stock

adjusted_daily_sales × safety_stock_days

11.00 × 14

= 154.0 units

Safety stock is the extra buffer that protects you from late shipments, demand spikes, or bad supplier timing.

Safety stock days coverage model

Reorder point

lead_time_demand + safety_stock

308.0 + 154.0

= 462.0 units

Once your inventory position falls to this level, you should be placing the next order.

Standard reorder point formula

Days of inventory cover

available_units ÷ adjusted_daily_sales

500 ÷ 11.00

= 45.5 days

This estimates how long current and incoming stock lasts if demand keeps moving at the current adjusted pace.

Inventory days of supply formula

Days until reorder

(available_units − reorder_point) ÷ adjusted_daily_sales

(500 − 462.0) ÷ 11.00

= 3.5 days

This is roughly how many days remain before inventory drops into the reorder zone.

Inventory position timing formula

Suggested order quantity

daily_sales × (lead_time + target_coverage + safety_stock_days) − available_units

11.00 × (28 + 45 + 14) − 500

= 457.0 units

This order size aims to survive the lead time and still leave you with target post-arrival coverage plus buffer stock.

Target coverage reorder quantity model

Cash required for the reorder

suggested_order_qty × unit_cost

457.0 × $8.75

= $3,998.75

The reorder decision is not only operational. It is also a working-capital decision, so this shows the cash needed to fund the buy.

Inventory purchase cash requirement formula

Key insight

At the current pace, your business is consuming about 11.00 units per day, so stocking decisions compound quickly.

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