Cash Flow Forecast: How to Build One for Your Ecommerce Brand
Your P&L says you're profitable. Your bank account says otherwise. A cash flow forecast bridges the gap — here's how to build one that prevents the cash crunch.
Jakob Sperber
Director
Finance
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Your P&L says you're profitable. Your bank account says otherwise. That gap isn't a mistake — it's a cash flow timing problem built into the structure of every ecommerce business. A cash flow forecast bridges that gap by showing you where the money goes before it goes there.
P&L vs Cash Flow
A P&L tells you if you're profitable over a period. A cash flow forecast tells you if you can afford to be profitable next week. They answer different questions. You need both.
For the underlying dynamics, see our guide on why your ecommerce cash flow is lying to you.
The 13-Week Cash Flow Forecast
13 weeks (one quarter) is the standard format. Long enough to see problems coming, short enough to be accurate. Each week gets a column. Rows are cash in and cash out.
Cash Inflows
Revenue by channel: Shopify direct (2–3 day payout), marketplace payouts (14–60 days), wholesale invoices (30–60 days)
Timing matters: Revenue earned this week may not hit your bank for 3–60 days depending on channel. Map the actual payout dates, not the order dates.
Refunds and chargebacks: Deduct from the week they're processed, not the week the original order was placed.
Cash Outflows
Inventory POs: The biggest lump sums. Map each PO to its payment due date.
Ad spend: Daily charges from Meta, Google, TikTok. Predictable but relentless.
Payroll: Fortnightly or monthly. Fixed and non-negotiable.
Rent and utilities: Monthly fixed.
Software: Shopify, Klaviyo, apps, analytics. Monthly recurring.
Tax obligations: BAS quarterly, income tax instalments, super. Don't forget these — they're large and infrequent.
Loan repayments: If you have financing, map every repayment date.
Building the Forecast: Step by Step
Start with your current bank balance.
Map committed cash out for the next 13 weeks: POs already placed, ad spend at current run rate, payroll, rent, upcoming tax payments.
Map expected cash in: Revenue at current run rate, adjusted for payout schedules. Be conservative — assume 90% of projected revenue.
Calculate the gap each week: opening balance + cash in − cash out = closing balance. If any week goes negative, you have a problem to solve before it arrives.
Run "what if" scenarios: What if revenue drops 20%? What if you increase ad spend 30%? What's your runway if a major PO hits earlier than expected?
Common Cash Flow Killers in Ecommerce
Inventory over-ordering. Optimistic demand forecasts lock up cash for months. Order based on data, not hope.
Scaling ad spend too fast. Going from $20k to $50k/month in ads while waiting for inventory PO payments is a cash crunch in waiting. Your CAC payback period determines how fast you can scale without external capital.
Seasonal stock builds without financing. A $200k BFCM inventory order in September means $200k less cash for October and November — right when you also need to increase ad spend.
Slow marketplace payouts. Amazon and The Iconic pay on 14–30 day cycles. If marketplace is your primary channel, you're always 2–4 weeks behind on cash.
When to Update: Weekly
Monthly is too slow. Cash moves too fast in ecommerce for monthly forecasting. Update every Monday morning: actual cash in/out from last week, adjust projections for the next 12 weeks.
This takes 30 minutes once the template is built. It's the 30 minutes that prevents the "we ran out of cash and didn't see it coming" conversation.
Tools
Excel or Google Sheets is fine for most brands under $5M. A simple 13-week template with inflow/outflow rows and a running balance. No fancy software needed.
For automation: Float, Fathom, or Futrli integrate with Xero/MYOB and can pull actuals automatically. Worth it at $3M+ when manual updates become tedious.
Financing Options When the Forecast Shows a Gap
Revenue-based financing (Wayflyer, Clearco): Borrow against future revenue. Good for bridging inventory POs. Expensive if payback is slow.
Business credit cards: 30–55 day float on ad spend. Effectively extends your DPO on marketing.
Inventory financing: Fund POs against confirmed demand or historical sell-through.
Invoice factoring: For wholesale — get paid on invoices immediately at a discount.
All financing has a cost. The forecast tells you whether the cost is justified by the growth it enables.
The Bottom Line
A cash flow forecast doesn't prevent problems. It prevents surprises. Map your inflows and outflows weekly. Know your runway at all times. And set your ad budget and growth targets based on what your cash position can actually support — not what your P&L says you "should" be able to afford.
See our ecommerce accounting guide for the management P&L structure that feeds into this forecast.
