Tutorial

How much inventory can you actually afford to reorder?

Restocking is where e-commerce cash goes to hide. Here's a simple way to work out how much stock you can afford to reorder without starving the rest of the business — and how to keep the answer current.

The Foreqast Team July 10, 2026 3 min read

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.

The monthly repurchase cost

Next month's restock = units sold this month × average purchase cost per unit
That keeps inventory level — you simply rebuy what you sold
To grow stock on purpose, multiply by an uplift (e.g. ×1.1 for +10%)

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:

B4=B2*B3 (this month's units × purchase cost)

	Jan	Feb	Mar	Apr
Units sold	820	910	1,050	980
Avg purchase cost (€)	14	14	14	14
Restock cost (€)	11,480	12,740	14,700	13,720

Repurchase cost — sell 820 units in January at €14 cost, and you'll spend €11,480 restocking (next month) just to stay level. The cost tracks last month's sales automatically instead of being a guess.

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:

B4=B2*B3*1.1 (+10% to grow stock)

	Jan	Feb	Mar
Restock to hold level (€)	11,480	12,740	14,700
Growth factor	1.10	1.10	1.10
Restock to grow +10% (€)	12,628	14,014	16,170

Growing on purpose — multiply by a growth factor to end each month with more stock than you sold. The extra €1,148 in January is the cash cost of building inventory, on top of holding level.

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:

Forecast	Jan 26	Feb 26	Mar 26	Apr 26	May 26
Revenue	47,560	52,780	60,900	56,840	59,160
Shop revenue Σ orders × AOV	€47,560	€52,780	€60,900	€56,840	€59,160
Orders Shopify	820	910	1,050	980	1,020
Avg order value Shopify	€58	€58	€58	€58	€58
Cost of goods	11,200	11,480	12,740	14,700	13,720
COGS (restocking) Σ prev-month orders × €14	€11,200	€11,480	€12,740	€14,700	€13,720
Avg purchase cost Manual	€14	€14	€14	€14	€14

The Foreqast forecast — cost of goods is a driver: previous-month orders × €14. April's projected €14,700 restock is simply March's 1,050 Shopify orders flowing through a month later — the forecast carries it forward with no manual rebuild.

Free 12-month cash-flow template (Shopify & WooCommerce)Excel & Google Sheets · formulas and cost drivers included

Know your safe reorder before you place it

Foreqast ties your restocking to real order volume and shows the cash-balance impact of any order — so you never trap cash you'll need.

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Common questions

How much cash should I keep back when reordering?

Enough to cover fixed costs for the full time between paying the supplier and collecting the revenue from that stock — lead time plus the time it takes to sell through. That period is the exposure, and it is almost always longer than founders estimate because it includes shipping, customs and the sell-through tail, not just manufacturing.

What happens if I reorder against my bank balance?

You are reading a number that has not yet had the month's payroll, rent or tax settlement taken out of it. That is why restocking is the single most common cause of an unplanned overdraft in e-commerce: the balance was real, but it was already spoken for.

Should I take a supplier discount for a larger order?

Only if the cash it ties up is cash you would not otherwise need. A 10% discount on stock that sits for four months is expensive if it forces you to cut ad spend in the meantime — the discount is measurable, the growth you did not buy is not.