Run it with less chaos · Every business
How Big a Cash Reserve Should a Service Business Keep?
A cash reserve is easiest to size in days of spending rather than in dollars, because days translate directly into how long the business could keep paying its bills through a slow stretch.
A practical target for most service businesses is at least one month of cash outflows held in reserve, built toward two to three months if revenue is seasonal or a few large customers pay slowly. For context, a JPMorgan Chase Institute study of 597,000 small businesses found that the median business held 27 days of outflows in cash, and a quarter held fewer than 13 days, so a full month already puts you ahead of half of the firms studied.
How to size and build your reserve
- Find your average monthly cash outflows. Add up everything that left the business account over the last 12 months, including owner pay and loan payments, and divide by 12.
- Work out your daily outflow. Multiply the monthly figure by 12 and divide by 365.
- Count your current buffer days. Divide today's cash balance (not counting money set aside for taxes) by the daily outflow.
- Set a target. Start with 30 days; move toward 60 to 90 days if your slow season runs longer than a month, if a handful of customers make up much of your revenue or if one broken van or chair would stop the work.
- Fund it on a schedule. Move a fixed share of profit, such as 10%, into a separate savings account every time you pay yourself, until the target is reached.
- Write the rule for using it. The reserve covers payroll, rent and owner pay during a shortfall; it is refilled before owner pay rises again.
| Average monthly cash outflows (Assumption) | $30,000 |
|---|---|
| Daily outflow (Calculated ($30,000 × 12 ÷ 365)) | $986 |
| Reserve at the 25th percentile (13 days) (Calculated ($30,000 × 12 ÷ 365 × 13)) | $12,822 |
| Reserve at the median (27 days) (Calculated ($30,000 × 12 ÷ 365 × 27)) | $26,630 |
| Reserve at 60 days (Calculated ($30,000 × 12 ÷ 365 × 60)) | $59,178 |
| Reserve at 90 days (Calculated ($30,000 × 12 ÷ 365 × 90)) | $88,767 |
Illustrative example; replace every assumption with your own numbers.
Why it works
A reserve sized in days gives the owner a clear answer to the question that matters during a bad month, which is how long the business can keep its promises to staff, landlord and household. Without one, the owner's own savings become the reserve; in the Federal Reserve's 2024 survey of small employer firms, 51% of firms facing financial challenges used the owner's personal funds and 48% used cash reserves. The labor-heavy industries that most service businesses belong to held fewer buffer days than average in the JPMorgan Chase Institute data, with personal services at 21 and repair and maintenance at 18, so a service business has more reason, not less, to build one on purpose.
Sources
- Farrell, D. and Wheat, C. Cash is King: Flows, Balances, and Buffer Days. JPMorgan Chase Institute, 2016. 597,000 small businesses.
- Federal Reserve Banks. 2025 Report on Employer Firms: Findings from the 2024 Small Business Credit Survey. 2025. 7,653 employer firms.
Related reading: Cash Flow, Not Sales, Is Why Many Small Businesses Fail · How to Stay Booked in the Slow Season Without Discounting · The 30-Minute Weekly Money Check: Invoices, Bills, Tax Savings and Payroll · Paying Yourself as the Owner: Salary, Draws and What to Set Aside
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