Most small businesses need working capital equal to 3-6 months of fixed operating expenses, or enough to keep a working capital ratio (current assets divided by current liabilities) between 1.5 and 2.0. For a shop running $60,000/month in overhead, that's $180,000-$360,000 in accessible cash or credit - not necessarily sitting in a checking account, but reachable within days.
The number that actually matters isn't a rule of thumb, though - it's your specific cash conversion cycle. Here's how to calculate your real need instead of guessing at a percentage.
The three ways to size the number
Ask three different lenders how much working capital you need and you'll get three different answers, because there are three legitimate ways to calculate it. Use whichever fits how your business actually spends money.
- Expense method: 3-6 months of fixed costs (rent, payroll, insurance, loan payments) - the safety-net approach, best for businesses with unpredictable revenue
- Ratio method: current assets / current liabilities, targeting 1.5-2.0 - the lender's approach, since it's what underwriters actually check
- Cash conversion cycle method: (days inventory held + days to collect receivables) minus days to pay your own bills, multiplied by daily costs - the precise approach for inventory-heavy or invoice-heavy operations
Real numbers by business type
The right reserve varies enormously by how fast your cash cycle turns. A used car lot floors inventory for 45-90 days before a sale converts it back to cash; a trucking company waits 30-45 days on freight invoices even after the load delivers. Slower cycles need bigger reserves.
| Business type | Typical cash cycle | Recommended reserve |
|---|---|---|
| Used car dealership | 45-90 days (floor to sale) | 4-6 months overhead |
| Trucking / owner-operator | 30-45 days (invoice to paid) | 2-3 months overhead |
| Auto repair shop | Same day - 2 weeks | 2-3 months overhead |
| Equipment dealer | 60-120 days | 4-6 months overhead |
| Service business (B2B, net-30) | 30-60 days | 3-4 months overhead |
What happens when the reserve is too thin
Undercapitalized businesses don't usually fail from a single bad month - they fail from a normal bad month hitting an account with no cushion. A slow week at the lot, one customer paying an invoice 20 days late, a truck needing an unplanned $4,000 repair: any of these is routine. Without reserves, any of them becomes an emergency that forces expensive, fast-turnaround borrowing instead of planned, cheaper borrowing.
That's the real cost of under-reserving - not the shortfall itself, but the fact that you fund it under pressure, at pressure pricing.
Reserve vs. line of credit: which to actually hold
Holding the full reserve in cash is the safest option and the most expensive - that money earns nothing while it sits idle. Most established businesses instead hold a smaller cash cushion (4-6 weeks) plus an open line of credit sized to cover the rest. The line costs nothing unless drawn, and draws instantly when the gap shows up.
Open the line before you need it
A line of credit approved during a strong month, sitting unused, is the cheapest insurance a small business can buy. Wait until the gap appears and you're applying for emergency capital under worse terms and slower timelines - the exact moment underwriting gets harder, not easier.
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How much to actually borrow if you're short
If your calculation shows a gap, don't borrow the theoretical maximum - borrow the gap plus a margin, sized to what your revenue can service. Lenders typically size working capital loans and lines at 70-120% of average monthly deposits, which caps how large a facility you'll realistically qualify for regardless of the textbook number. Match the ask to both the need and the approval math.
We size the request to what actually funds
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FAQ
What is a healthy working capital ratio for a small business?+
Most lenders and accountants target 1.5-2.0 (current assets divided by current liabilities). Below 1.0 means liabilities exceed liquid assets - a warning sign. Above 2.5 can mean cash is sitting idle instead of growing the business.
How many months of expenses should a small business keep in reserve?+
3-6 months of fixed operating costs is the standard range. Businesses with volatile revenue or slow cash cycles (dealerships, equipment dealers) should target the top of that range; steadier service businesses can run closer to 3.
Is it better to save cash or open a line of credit for working capital?+
Most businesses do both: a smaller cash cushion (4-6 weeks) for instant needs, plus a line of credit sized to cover the rest. The line costs nothing unused and avoids tying up capital that could otherwise grow the business.
How much working capital do I need to start a business?+
Beyond your startup costs, plan for 6 months of operating expenses before the business is expected to break even - most new businesses take longer than projected to reach positive cash flow, and undercapitalized startups are the ones that don't survive the gap.
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