How to build a 13-week cash flow forecast for an e-commerce brand

Closing cash = opening cash + bank receipts − cash payments. Repeat this calculation for thirteen weeks, using each closing balance as the next opening balance. Compare every week with a cash floor chosen by the owner.

A useful forecast answers three questions: when is cash tightest, which receipts or payments create that pressure, and what must change before the commitment is made? Total sales and monthly profit cannot answer those questions on their own.

Build the first version from current records. Put a source, responsible person and last-checked date beside each assumption so that the team can update the forecast when a payout, quote or delivery date changes.

Set the opening date, entity and currency. Reconcile available bank cash at that cutoff and identify initiated payments. Show restricted balances and held processor funds separately from money available to pay suppliers.

Gather the obligations already committed before adding future growth. An unpaid supplier invoice, PO balance or payroll debit matters even if the accounting system has not yet recorded its payment.

For captured sales, use the provider payout record and the expected bank receipt date. For future sales, document the sales assumption, refunds, provider deductions and collection lag. Keep these two types of receipt visible so that a change in demand can be distinguished from a change in settlement timing.

Separate providers where their schedules differ. Shopify Payments settlement and payout scheduling both affect timing; check the relevant account rather than applying the same delay to every channel.

Choose one convention for fees and refunds. When the forecast receipt is a net bank deposit, those deductions are already reflected in the amount. When starting from gross collections, reconcile the separately listed deductions to the net deposit.

Record approved borrowing or owner funding on a separate line, with its evidence and expected date. Leave an unresolved funding requirement visible until an actual funding source is agreed.

For each PO, list the unpaid deposit, supplier balance, freight and other separately payable costs. Use due dates or expected bank debit dates. A deposit paid before the opening cutoff is already reflected in opening cash.

Match PO and payable schedules by identifier. An invoice for a supplier balance and the same balance on the PO list represent one payment. Check the operating-payment schedule for that duplication as well.

Inventory payments belong on their cash dates. COGS belongs to the accounting period in which the related inventory is sold. Include payroll, rent, advertising billing and other obligations in the same dated forecast; add applicable tax, debt, asset and owner movements separately.

Use weeks as columns and cash categories as rows. With outflows entered as positive amounts, calculate opening cash + receipts − inventory payments − operating payments + other signed movements. If payment rows are negative instead, add them once.

Link the next opening balance to the previous close. Check that opening cash plus the sum of all net movements equals final cash. Also compare the lowest balance with the chosen buffer, recording the date and amount of any shortfall.

Keep the receipt and payment detail available behind the totals. A balance alert becomes actionable only when you can identify the commitments that produced it.

The scenario starts with $85,000. In week 1, $54,000 receipts − $12,000 inventory payments − $40,000 operating payments produce closing cash of $87,000. That becomes week 2’s opening balance.

Week 6, beginning 9 November, opens at $82,000. After $58,000 receipts, $67,000 inventory payments and $41,500 operating payments, cash closes at $31,500. It is $8,500 below the scenario’s $40,000 cash floor. The inventory payment is the first commitment to investigate.

The full horizon reconciles: $85,000 + $794,000 receipts − $242,000 inventory payments − $546,000 operating payments = $91,000. Ending above the opening balance does not remove the shortfall in week 6.

Keep the base forecast and change one documented assumption at a time. Move a delayed receipt from its original week to its revised week. Extend the horizon for receipts falling beyond it, and retain payments that remain due when sales slow.

Test the supplier schedule alongside delivery and stock availability. A later balance payment helps cash only on the agreed terms; a later delivery can also delay receipts. A smaller order may change freight per unit and stock cover, so update those consequences together.

Inspect daily cash around a tight payroll, tax or supplier date. A positive weekly closing balance can conceal an earlier shortfall when the payment leaves before the receipt arrives.

Archive the previous version, reconcile actual receipts and payments, and explain the difference. Roll the horizon forward to thirteen weeks. Carry overdue obligations to their revised dates with their original identifiers.

Update the source assumption as well as the number. A late receipt, amended order or unexpected recurring debit should change the relevant future weeks and have an assigned follow-up.

Start with the first date that lacks headroom. Confirm the underlying commitments and compare an agreed payment schedule, a smaller order, spending changes or documented funding. Recalculate the full horizon for each option.

The bookkeeper verifies balances and actuals; operations confirms orders and delivery assumptions; the finance preparer maintains the forecast. The owner chooses the cash floor and authorizes the commitments.

For an upcoming deposit, use the inventory-order guide to record the approval conditions. Bring the dated forecast and unresolved assumptions into the cash-planning discussion so the next step addresses a specific decision.