Cash Flow Calculator
Monthly Net Cash Flow
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Annual Cash Flow
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Cash Runway
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Monthly Burn Rate
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How the Cash Flow Calculator Works
Cash flow is the net amount of money moving into and out of a business during a specific period. This calculator helps you track that movement monthly. Enter your revenue sources and expense categories to instantly see your net cash flow, annualized cash flow, monthly burn rate, and cash runway. Results update in real time as you adjust any input, making it easy to model different revenue and expense scenarios.
Cash flow management is the single most critical financial discipline for any business. According to a U.S. Small Business Administration analysis, 82% of business failures are caused by poor cash flow management rather than lack of profitability. Understanding exactly how much cash flows in and out each month — and how long your reserves will last — is essential for making informed decisions about hiring, expansion, and investment.
Cash Flow Formulas and Methodology
Monthly Net Cash Flow = Total Monthly Income - Total Monthly Expenses. A positive number means more cash is coming in than going out. A negative number indicates you are spending more than you earn, which depletes your cash reserves over time.
Annual Cash Flow = Monthly Net Cash Flow x 12. This projection assumes consistent monthly patterns. In practice, most businesses experience seasonal variation, so quarterly analysis provides a more nuanced picture.
Monthly Burn Rate = Total Monthly Expenses - Total Monthly Income (when negative). Burn rate measures how quickly a company with negative cash flow consumes its cash reserves. This metric is especially important for startups and businesses operating at a loss.
Cash Runway = Cash on Hand / Monthly Burn Rate. This tells you how many months you can continue operating at the current burn rate before running out of cash. If your net cash flow is positive, the calculator shows "Profitable" instead of a runway figure.
Free Cash Flow (FCF) = Operating Cash Flow - Capital Expenditures. While this calculator focuses on operating cash flow, free cash flow is the ultimate measure of how much discretionary cash a business generates after maintaining its asset base.
Key Cash Flow Terms
Operating Cash Flow: Cash generated from core business operations — collecting revenue, paying suppliers, salaries, rent, and utilities. This is the most important cash flow category because it shows whether the business can sustain itself without external funding.
Investing Cash Flow: Cash spent on or received from long-term assets — purchasing equipment, vehicles, property, or selling investments. Negative investing cash flow usually indicates a business is investing in growth.
Financing Cash Flow: Cash from loans, investors, or returning money to stakeholders — bank loans received or repaid, equity raised, dividends paid, or shares repurchased.
Gross Burn Rate: Total monthly expenses regardless of revenue. A startup spending $50,000/month has a $50,000 gross burn rate even if it earns $20,000 in revenue.
Net Burn Rate: Monthly expenses minus monthly revenue. The same startup has a $30,000 net burn rate ($50,000 - $20,000). Net burn is more informative for companies with revenue.
DCF (Discounted Cash Flow): A valuation method that estimates a business's value based on projected future cash flows discounted to present value. Investors use DCF models to determine whether a company's stock is over- or undervalued.
Cash Flow Health Reference Table
| Metric | Healthy Range | Warning Sign | Critical |
|---|---|---|---|
| Cash Runway | 12+ months | 6-12 months | Under 6 months |
| Operating Cash Flow | Consistently positive | Occasionally negative | Negative for 3+ months |
| Cash Reserve (% of monthly expenses) | 3-6 months | 1-3 months | Under 1 month |
| Accounts Receivable Days | Under 30 days | 30-60 days | Over 60 days |
| Revenue-to-Expense Ratio | Above 1.2 | 1.0-1.2 | Below 1.0 |
Practical Cash Flow Examples
Example 1 — Profitable Small Business: A consulting firm earns $25,000/month in revenue with $18,500 in total expenses (rent $3,000, payroll $12,000, utilities $500, marketing $2,000, other $1,000). Net cash flow is +$6,500/month or +$78,000 annually. With $50,000 cash on hand, the business is comfortably profitable and building reserves.
Example 2 — Startup Burning Cash: A pre-revenue startup has $250,000 in seed funding and monthly expenses of $35,000 (3 engineers at $8,000 each, $4,000 rent, $3,000 marketing, $4,000 tools and infrastructure). With zero revenue, the gross and net burn rate are both $35,000/month. Cash runway = $250,000 / $35,000 = 7.1 months. The founders need to either generate revenue or raise additional funding within 4-5 months to maintain a safety buffer.
Example 3 — Seasonal Business Managing Cash Gaps: A landscaping company earns $40,000/month from April through October but only $5,000/month from November through March. Monthly expenses average $22,000 year-round. During peak season, the business generates $18,000/month in positive cash flow ($126,000 total over 7 months). During the off-season, it burns $17,000/month ($85,000 over 5 months). The company needs at least $85,000 in cash reserves entering November to survive winter without a credit line.
Tips for Managing Business Cash Flow
Invoice immediately and follow up early: Send invoices the day work is completed or goods are delivered. Follow up on payment at day 15, not day 45. Every day of delayed collection costs your business in opportunity cost and increased risk of non-payment.
Negotiate payment terms strategically: Ask suppliers for 45-60 day payment terms while requiring customers to pay within 15-30 days. This timing gap keeps cash in your account longer and reduces the need for external financing.
Build a cash reserve before you need it: Set aside 3-6 months of operating expenses in a separate savings account. This buffer protects against unexpected downturns, late-paying customers, and seasonal revenue dips without requiring emergency borrowing.
Review cash flow weekly, not monthly: Monthly reviews can miss dangerous trends. A weekly 15-minute cash flow check lets you spot problems (rising expenses, declining collections) before they threaten the business.
Separate operating and savings accounts: Keep day-to-day cash in an operating account and reserves in a separate account. This prevents accidentally spending reserve funds and makes cash position immediately visible.
Plan for taxes quarterly: Set aside 25-30% of profit each month in a dedicated tax account. Businesses that fail to plan for quarterly tax payments often face cash crunches in April, June, September, and January.
Frequently Asked Questions
What is the difference between cash flow and profit?
Cash flow and profit measure different things. Profit (net income) is an accounting concept that subtracts all expenses from revenue, including non-cash expenses like depreciation and amortization. Cash flow measures the actual movement of money into and out of your business. A company can be profitable on paper but cash-flow negative if customers pay late, inventory builds up, or large capital expenditures consume cash. Conversely, a business can have positive cash flow while reporting losses if depreciation exceeds capital spending. Cash flow is often considered a more reliable indicator of financial health because it reflects reality rather than accounting conventions.
What is free cash flow and why is it important?
Free cash flow (FCF) is the cash a business generates after accounting for capital expenditures needed to maintain or expand its asset base. The formula is: FCF = Operating Cash Flow - Capital Expenditures. Free cash flow represents the money available for dividends, debt repayment, share buybacks, acquisitions, or reinvestment in growth. Investors value FCF because it measures how much discretionary cash a business truly generates. A company with strong earnings but weak FCF may be spending heavily on equipment or facilities. Consistently positive FCF is one of the strongest signals of long-term business viability and shareholder value creation.
What is cash runway and how do I calculate it?
Cash runway is the number of months a business can continue operating before running out of cash, given its current burn rate. The formula is: Cash Runway = Cash on Hand / Monthly Net Burn Rate. For example, if you have $150,000 in cash and spend $10,000 more than you earn each month, your runway is 15 months. Startups and pre-profit businesses use runway as a critical planning metric. Most advisors recommend maintaining at least 6-12 months of runway. When runway drops below 6 months, it signals urgent need for cost reduction, revenue acceleration, or fundraising. This calculator computes runway automatically when your net cash flow is negative.
What are the three types of cash flow?
The cash flow statement divides cash movements into three categories. Operating cash flow covers day-to-day business activities: revenue collection, payments to suppliers, salaries, rent, and utilities. This is the most important section because it shows whether core operations generate cash. Investing cash flow tracks purchases and sales of long-term assets like equipment, property, or securities. Negative investing cash flow usually indicates a business is investing in growth. Financing cash flow records transactions with creditors and owners: bank loans received or repaid, equity raised, dividends paid, or shares repurchased. Healthy businesses typically show positive operating cash flow, negative investing cash flow, and variable financing cash flow.
How do I improve my business cash flow?
Start by shortening your accounts receivable cycle. Invoice immediately upon delivery, offer small discounts for early payment (2/10 net 30), and follow up on overdue accounts within days. Second, negotiate longer payment terms with suppliers — if you can pay in 45 or 60 days instead of 30, you keep cash longer. Third, manage inventory carefully since excess inventory ties up cash. Fourth, reduce fixed costs by renegotiating leases, eliminating unused subscriptions, and considering variable cost structures. Finally, build a cash reserve equal to 3-6 months of operating expenses. Even profitable businesses fail when temporary cash flow gaps cannot be covered.
What is a good burn rate for a startup?
A good burn rate depends on the company's stage, funding, and growth trajectory. Pre-revenue startups typically aim for a gross burn rate that allows 18-24 months of runway between funding rounds. If you raised $2 million, a monthly burn of $80,000-$110,000 provides adequate runway. Net burn rate (expenses minus revenue) is more informative for companies with some revenue. As a rule of thumb, monthly burn should not exceed 10-15% of total funding for early-stage companies. Growth-stage startups with product-market fit may intentionally increase burn to capture market share, but should demonstrate improving unit economics. Track both gross and net burn monthly and re-forecast quarterly.