Q3 Cash Runway Plan: How Much Can You Spend on Ads, Inventory, and Owner Pay?

Q3 is where ecommerce brands often make decisions that decide the rest of the year. Inventory for later campaigns gets ordered. Creative tests start. Ad budgets rise. Agencies pitch new retainers. Founders try to take a reasonable owner draw while still funding growth.

The danger is that each decision can look reasonable on its own. Together, they can create a cash crunch.

A Q3 cash runway plan helps you decide what the business can actually afford.

Start With Cash, Not Revenue Goals

Most planning starts with a revenue target:

"We want to do $300,000 in Q3."

That is fine as a goal, but it is not a spending plan.

Start with:

• Cash in the bank
• Expected payouts
• Upcoming supplier payments
• Inventory commitments
• Fixed monthly expenses
• Current monthly ad spend
• Owner draw
• Tax or debt payments
• Minimum cash buffer

Then ask:

After these obligations, how much cash is available for growth experiments?

That number is your real budget.

Calculate Baseline Runway

Use the simple formula:

Cash runway = Cash in bank / Monthly cash burn

If the business is cash positive, calculate your buffer:

Cash buffer months = Cash in bank / Average monthly operating expenses

For Q3 planning, do both:

1. Runway if sales continue as expected.
2. Runway if sales drop 20 percent.

The second version is the one that protects you.

Separate Committed Spend From Flexible Spend

Not all spending can be adjusted quickly.

Committed spend includes:

• Supplier deposits
• Inventory balances due
• 3PL minimums
• Software contracts
• Agency retainers
• Payroll
• Rent
• Loan repayments
• Tax obligations

Flexible spend includes:

• Incremental ad tests
• New creative production
• Optional influencer seeding
• Experimental tools
• Nonessential contractors
• Extra inventory depth

You should know how much of Q3 cash is already committed before approving flexible spend.

Decide Inventory First

Inventory often has the longest cash cycle, so it should be planned before ad budget.

For each reorder, answer:

• What cash payment is due?
• When is it due?
• When will inventory arrive?
• How many weeks of cover will it create?
• What sell-through is needed to recover cash?
• What contribution margin does the product generate?
• What happens if demand is 20 percent lower than forecast?

If a reorder uses most of your cash buffer, ad spend needs to be more conservative until the inventory turns.

Set Ad Spend From Break-Even Math

Ad budget should not be set only by last month's ROAS.

Set it from:

• Current contribution margin
• Break-even ROAS
• Cash runway
• Inventory availability
• Payback period
• Product return rate

If you spend $30,000 on ads in July, how quickly does that cash return? Same week? Two weeks? After a 30-day return window? After repeat purchase?

Paid ads can be profitable and still create short-term cash pressure.

Protect Owner Pay

Owner pay should be part of the plan, not an afterthought.

A founder who pays themselves nothing for too long creates a different kind of business risk. A founder who withdraws too much can weaken runway.

Use three levels:

Owner pay should move with business health, but it should not be random.

Build a Q3 Cash Budget

Create four buckets:

1. Operating reserve. Minimum cash you do not touch.
2. Inventory. Reorders, freight, duties, prep, packaging.
3. Growth. Ads, creative, creators, email/SMS, testing.
4. Owner and obligations. Owner draw, taxes, debt, required payments.

Then assign dollars based on cash available, not optimism.

Example:

If actual cash changes, update the buckets. The plan should move with reality.

Set Trigger Points

Before Q3 starts, decide what will cause you to change course.

Examples:

• If runway drops below 2 months, pause nonessential ad tests.
• If ROAS stays below break-even for 10 days, cut campaign spend.
• If inventory sell-through is 25 percent slower than forecast, reduce reorder depth.
• If return rate rises above target, stop promoting that SKU.
• If cash buffer is above target at month end, release extra growth budget.

Trigger points reduce emotional decision-making.

Review Weekly

Q3 planning is not useful if you only look once.

Every week, review:

• Cash in bank
• Upcoming cash out
• Expected payouts
• Inventory commitments
• Ad spend against break-even
• Contribution profit
• Return rate
• Runway

This should take 15 minutes if the data is ready.

How Nummbas Helps

Nummbas helps bring together the numbers a Q3 runway plan needs: revenue, ad spend, costs, shipping, expenses, cash visibility, and profitability.

That means you can see whether the business can afford the next ad push, inventory buy, or owner draw without building a new spreadsheet every week.

Q3 growth should be funded by clear numbers, not hope.