The 13-Week Cash Flow Forecast Every DTC Brand Needs

Annual budgets are theatre. Monthly forecasts are too coarse for ecommerce. The 13-week rolling cash forecast is the single most useful operating tool we install in DTC clients — it answers, every Monday, the only question that matters: will we run out of money in the next quarter, and if so, when.

Why 13 weeks

• Long enough to see a full inventory cycle (PO → arrival → sell-through).
• Short enough that every line is forecastable with real precision.
• Matches the cadence of supplier terms, ad-budget reviews and quarterly board cycles.

Structure

Rows = cash inflows and outflows Columns = 13 weeks forward, week-ending dates Each cell = expected USD cash movement that week Final row = closing cash position

The required line items

Inflows

• Shopify / online store payouts (net of fees, with payout lag built in — usually T+2)
• Marketplace payouts (Amazon, TikTok Shop) with their bi-weekly cycles
• Wholesale & retail receivables, by customer if material
• Financing inflows (loan draws, RBF advances) — separated, never blended into revenue
• Tax refunds, grants, other

Outflows

• Inventory POs — scheduled by deposit date and balance date
• Freight, duties, 3PL — broken from inventory because the timing differs
• Marketing spend (by channel — you'll cut by channel later)
• Payroll & contractors
• SaaS & subscriptions
• Rent, utilities, professional fees
• Tax payments (VAT/sales tax/income)
• Financing repayments — principal AND interest as separate lines
• Owner distributions

Update cadence

Every Monday morning. The model takes 20–30 minutes once it's built. You replace the just-finished week's forecast with actuals, roll forward a fresh week 13, and adjust any line where reality has diverged from forecast by more than 10%.

Variance discipline

Track forecast accuracy weekly. Within 90 days a healthy model should be within ±5% on revenue lines and ±10% on inventory. If you're consistently off, the forecast logic is wrong — not reality.

Common mistakes

• Putting revenue in the week of the order instead of the week of the payout.
• Forgetting credit-card processing reserves (typically 1–3% held back).
• No buffer line for the unexpected — add one at 2–5% of weekly outflows.
• Mixing accrual P&L logic into a cash model — never.
• Updating monthly. The whole point is weekly.

How to actually use it for decisions

• Closing cash < 8 weeks of opex anywhere in the next 13 weeks → board-level conversation.
• Negative cash week → trigger PO deferral, ad budget cut, or financing draw.
• Surplus cash > 16 weeks opex → invest in inventory ahead of peak or pay down expensive debt.

Tools

Google Sheets is fine up to ~$10M revenue. Past that, switch to a real planning tool (Fathom, Float, or a lightweight cube in BigQuery). The discipline matters more than the software.

We build this model with every new fractional CFO client in week one. Grab the 13-Week Cash Flow Template if you'd like a sanitised version to start from.