Cash Flow
The movement of money in and out of your accounts over a period; positive cash flow means income exceeds spending, negative means the opposite.
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Cash flow is the movement of money into and out of your accounts over a defined period, usually a month. Positive cash flow means more came in than went out; negative cash flow means the reverse. It is the most immediate measure of personal financial health, more responsive than net worth and easier to influence in any given month.
How it works
Sum every inflow during the period: salary, side income, refunds, interest, gifts. Sum every outflow: bills, groceries, transport, dining, subscriptions, debt payments, transfers to savings. Inflows minus outflows equals net cash flow. The result tells you whether the month grew your liquid position or shrank it. Tracking cash flow monthly reveals patterns that a single look at a bank balance misses: a balance can stay flat while you quietly slide into debt, or grow steadily even though it feels like nothing is happening.
Why it matters
You cannot save, invest, or pay off debt without positive cash flow. Net worth can grow from rising asset prices, but only consistent positive cash flow is something you control. Tracking it month over month also surfaces problems early: three months of negative flow is a warning that a fixed cost has crept too high or that variable spending is out of control. It is the heartbeat metric of personal finance.
Example
In a single month: salary $3,000, freelance $400, interest $5. Total inflow $3,405. Outflows: rent $1,100, groceries $380, transport $150, utilities $130, dining $220, subscriptions $45, gym $30, insurance $80, savings transfer $400, debt payment $300, miscellaneous $180. Total outflow $3,015. Net cash flow: +$390. Repeat next month and trend it. A six-month rolling average is more useful than any single month.
When to use it
- You want a single monthly health metric for your finances
- You suspect you are overspending but the bank balance does not show it
- You are deciding whether you can take on a new fixed cost
- You are evaluating whether a side income is materially helping
- You are forecasting a large upcoming expense