How much inventory can you actually afford to reorder?

Reordering stock is the biggest single cash decision most store owners make each month — and the easiest one to get wrong. Order too little and you sell out; order too much and your cash is trapped on a shelf while rent, ads and payroll still need paying. Here's how to size it — starting with the question that actually drives the number: what does it cost you just to restock each month?

First question: what does restocking cost each month?

Restocking isn't a one-off — it's a recurring cost. Every month you repurchase roughly what you sold, just to keep the shelves full. So before you ask "can I afford a big reorder?", pin down the recurring number: your monthly repurchase cost. The clean way to project it is to push this month's sales onto next month's costs.

It's exactly the logic a forecast uses to project cost of goods forward: last month's unit sales set this month's restock bill. Here it is across a few months:

Sell more, and the restock rises with it; sell less, and it falls. If you'd rather build inventory up than just hold it level, multiply by a growth factor:

That recurring number is the backbone of every inventory decision — the one figure your cash-flow plan should carry forward each month.

The same projection, without the monthly rebuild

Doing this by hand means re-pulling last month's unit sales and recomputing the restock line every month. Foreqast makes it a built-in driver: cost of goods is projected as previous-month orders × average purchase cost, fed by your real Shopify order volume, so the restock line moves with demand on its own. Change the purchase cost or a growth assumption and every future month updates — and the projected cash-balance line shows at a glance whether a reorder keeps you above your buffer. Here's the same example inside the app: