How do I know if I can afford a stock order?

Turn the order into a payment schedule (deposit and balance dates from your supplier terms), lay those payments onto a weekly cash forecast alongside payroll, tax, ad spend and your other stock orders, and find the lowest projected week. If the low week leaves you less headroom than one normal payout delay would eat, you can't comfortably afford the order on those dates: move it, shrink it, or renegotiate the terms.

What is a safe minimum cash buffer for an ecommerce brand?

A working rule: your low week should never dip below roughly one week of operating costs plus one delayed platform payout. For many small brands that's £5,000 to £15,000. If a stock order pushes the low week under your figure, the order dates need to move even if the demand math says order now.

Should I delay a reorder if cash is tight?

Often yes, and the stock math usually tolerates it better than people fear. Check the delay against your reorder point and safety stock: a two-week shift that keeps you above safety stock costs little, while the same shift can double your cash headroom in the low week.

Blog / Reorder math

Can I afford this reorder? How to run the cash and stock numbers together

By Rory McLaughlan, Shopify store owner · 8 September 2026 · 8 minute read

The short answer: an order is affordable when your projected cash balance stays above your minimum buffer in every week the order touches, not just on the day you place it. To know that, you turn the order into a payment schedule, lay it onto a weekly cash calendar with everything else that's leaving the account, and look at the lowest week. Here's the five-step version, then a full worked example.

This picks up where how much stock should I order left off. That post sized the order: 1,000 units at £9.20 landed, £9,200 all-in. This one decides whether to place it.

The five-step affordability check

Turn the PO into a payment schedule. Your supplier terms, not the invoice total, are what hit the bank. 30% deposit on order and 70% on shipping is common: for our £9,200 order that's £2,760 now and £6,440 in about five weeks.
Build the weekly cash calendar. Eight weeks is enough. Start from today's balance, add your average weekly net from trading (sales in, minus ad spend, ops and subscriptions), then place the lumpy items on their real dates: payroll, VAT or sales tax, loan payments, and every other stock order.
Drop the PO payments in and find the low week. The question is never "is the total affordable", it's "which week does this order make dangerous".
Compare the low week to your buffer. Pick a hard floor and treat it as real. A sane floor: one week of operating costs plus one delayed platform payout, because both happen.
Decide with three honest options. Proceed; shift or shrink the order; or renegotiate the terms. All three are wins compared to finding out in week six.

The worked example

Same brand as the sizing post. Today's balance £22,000, average weekly net from trading +£2,500. Monthly payroll £6,500 (weeks 2 and 6), VAT quarter £11,200 due week 3. The order: £2,760 deposit in week 1, £6,440 balance in week 5.

Week	Trading net	Lumpy items	Closing balance
Start			£22,000
1	+£2,500	Deposit −£2,760	£21,740
2	+£2,500	Payroll −£6,500	£17,740
3	+£2,500	VAT −£11,200	£9,040
4	+£2,500		£11,540
5	+£2,500	Balance −£6,440	£7,600
6	+£2,500	Payroll −£6,500	£3,600 ← low week
7	+£2,500		£6,100
8	+£2,500		£8,600

The order "fits": no week goes negative. But look at week six. £3,600 is one delayed Shopify payout or one ad-spend overrun from zero, and it lands the week after the balance payment, which is exactly when you can't cancel anything. By the day-you-place-it test this order looked easy, £22,000 in the bank against a £2,760 deposit. The low-week test tells the truth.

Same order, moved two weeks

Shift the PO so the deposit lands in week 3 and the balance in week 7:

Week	Lumpy items	Closing balance
1		£24,500
2	Payroll −£6,500	£20,500
3	VAT −£11,200, deposit −£2,760	£9,040
4		£11,540
5		£14,040
6	Payroll −£6,500	£10,040
7	Balance −£6,440	£6,100 ← low week
8		£8,600

Same order, same totals, and the low week went from £3,600 to £6,100. Nearly double the headroom, bought with a two-week shift. On the stock side, check the delay against your reorder point and safety stock: in this example the brand was 11 days above its reorder point, so a two-week shift eats the margin but keeps the safety buffer intact. That's the whole trade, laid out honestly: a little stock risk for a lot of cash safety, and you get to choose it instead of discovering it.

If the shifted order still breaches your floor: shrink it (order 700 units instead of 1,000 and reorder sooner), or renegotiate terms (a 20% deposit or 60-day balance moves the whole schedule). Suppliers say yes to this more often than founders expect, because a customer who plans payments is a customer who makes them.

Why nobody's tool does this for you

Your inventory planner recommends the order but can't see your bank. Your cashflow app sees the bank but doesn't know the order exists until you type it in as a budget line, and it goes stale the moment the supplier slips a week. So the low-week check lives in a spreadsheet you rebuild every time, or in your head. That gap is the entire reason Cushion exists.

Cushion runs this check automatically, every night

Cushion joins your cashflow, your stock and your sales forecast on one screen, with read-only connections to your store, your books and your bank. 14 days free, then £299 a month, cancel any time.

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