Startup budget: calculate the cash needed before launch

To calculate startup funding, put launch payments and operating cash movements on a calendar, find the lowest balance, and add enough funding to keep that balance above your chosen cash reserve. Subtract money already available to the business. The sum of startup expenses alone misses a payment that falls before the first customer receipt.

Build the budget from payment commitments

Start with a list of what must be paid, how much and when. A $12,000 equipment order with a 40% deposit is two cash events: $4,800 at order and $7,200 at settlement. Recording $12,000 only on the opening date hides the deposit deadline. Recording the deposit as well as the full invoice counts $4,800 twice.

Use supplier quotes, the lease payment calendar, planned payroll dates and inventory purchase terms. Include refundable deposits because they still use cash while held by someone else. Keep a separate flag for costs that can actually be deferred or cancelled; removing a signed payment from a scenario does not remove the obligation.

The SBA startup-cost guidance provides a useful inventory of one-time and recurring costs. After listing them, assign their cash dates. Separate owner contributions and loan receipts from customer sales, and count financing only in the period when it is expected to be available under its conditions.

Calculate the low point before adding new funding

Assume the business already has $15,000 of unrestricted owner cash. Launch commitments are $45,000. In the first trading month it collects $6,000 and pays $20,000; in the second it collects $12,000 and pays $10,000. The owner chooses an $8,000 reserve to retain for upcoming payments. These are planning assumptions for this example.

The first row is $15,000 − $45,000 = −$30,000. The next row carries that balance forward: −$30,000 + $6,000 − $20,000 = −$44,000. The lowest balance is −$44,000. To lift it to the $8,000 reserve, additional funding must be $52,000, available before the launch payments. Total opening cash becomes $67,000, including the owner's $15,000.

In Excel, place the existing $15,000 in D3, the receipts in B4:B6, payments in C4:C6 and the reserve in F2. Enter =D3+B4-C4 in D4 and copy it down. Additional upfront funding is =MAX(0,$F$2-MIN(D4:D6)). Keep this calculation based on cash before the proposed funding; including the same funding inside its own requirement creates a circular calculation.

With $52,000 added upfront, the closing balances become $22,000, $8,000 and $10,000. An aggregate calculation using only the final $42,000 deficit would request $50,000 and miss the month-one reserve by $2,000.

Test a timing delay without changing total sales

Move the $6,000 month-one receipt into month two. Payments and the total receipts over both months stay unchanged. Before new funding, cash is now −$30,000 after launch, −$50,000 after month one and −$42,000 after month two. Required additional funding becomes $58,000: $8,000 minus the −$50,000 low point.

The delay creates an extra $6,000 peak funding need even though the final unfunded balance is unchanged. This is why an annual revenue forecast or a two-month cash total cannot settle the opening funding decision. Around payroll, rent, deposits and tax dates, split monthly columns into weeks or individual payment dates; a month-end minimum can still miss an earlier shortage.

Choose what to change if the funding is unavailable

Return to the dated commitments. A staged equipment purchase might move a payment beyond the cash low point. A later opening may reduce immediate equipment spending but add another month of rent and payroll. Model both effects before calling the delay a saving. A customer deposit improves cash only if it can genuinely be collected before the supplier payment.

Keep the reserve separate from expenses. It is cash you intend to retain, not another supplier payment. Explain its purpose, such as the next payroll and rent, and check that those same commitments are not counted twice. Where a reserve changes by week, compare each balance with that week's requirement rather than applying one constant number.

Continue the forecast beyond the opening period until the business has a credible cash path. The 13-week cash forecast develops the near-term schedule; the break-even and capacity guide checks whether the assumed trading volume can cover the chosen operating costs. Profitability and funding timing need both calculations.