Personal Cash Flow Projection Calculator
Cash flow is the picture of money moving in and out over time — not a single year-end number. You can be comfortably "in the black" for the year and still hit a wall in the exact month a tuition bill or a tax payment lands, because the annual total never tells you when your balance dips lowest. The calculator above answers precisely that question. You enter your starting cash, your recurring monthly inflows and outflows, and any one-time events (a Tet bonus, school fees, a deposit on a car, a tax bill), and it projects your balance forward 3 to 24 months, flagging any month that would turn negative.
Two terms are worth keeping separate. Net monthly flow is income minus expenses within a single month — it can be positive most months and sharply negative in a month with a lumpy bill. Closing balance is what is left after that net flow is added to the previous month's balance; this is the figure that actually determines whether your payment clears. A healthy plan is one where the closing balance never falls below zero across the whole horizon, including the month with the largest single outflow.
For foreigners earning and spending in Vietnam, the wrinkle is the bonus calendar: a large 13th-month or Tet bonus arrives in one lump, while annual costs such as tuition or a visa renewal hit on their own schedule. In the illustrative example below — a 50.000.000 VND starting balance, 30.000.000 VND/month salary, 20.000.000 VND/month of recurring costs, a 40.000.000 VND Tet bonus and 25.000.000 VND of tuition — the balance ends at 185.000.000 VND after 12 months with a low point of 50.000.000 VND. Every figure here is an illustrative assumption; replace them with your own to get a realistic projection.
How the calculator projects your balance
A month-by-month simulation
The tool loops over each month from 0 to (horizon − 1). For every month it sums all inflows and all outflows that fall due that month, computes the net flow, and carries the running balance forward:
Net flow (month) = Σ income that month − Σ expenses that month
Closing balance = previous closing balance + net flow
| Term | Meaning |
|---|---|
| Starting balance | Cash you hold before month one |
| Recurring item | Income/expense that occurs in every month (salary, rent, living costs) |
| One-time event | Income/expense that occurs in exactly one month you choose (bonus, tuition, a big purchase) |
| Net flow | The month's income minus its expenses (can be negative) |
| Closing balance | Cash remaining after adding the net flow |
Three result metrics
- Final balance — the closing balance in the last month of the horizon: what you end with.
- Minimum cash reserve — the lowest closing balance across the whole horizon. If this is negative, you run short of cash at some point even if the yearly total is positive.
- Total net flow — total income minus total expenses over the horizon. It equals exactly (final balance − starting balance), which is a quick way to sanity-check the output.
Why timing beats totals
This is the core insight a year-end balance sheet hides. Two people with identical annual income and expenses can face very different liquidity risk: the one who front-loads a big outflow before a bonus arrives can break their balance, while the one who schedules it after the bonus never does. Use the tool to drag a one-time event to a different month and watch how the minimum reserve moves — that is the lever you control without earning a single dong more.
What the model leaves out
It assumes recurring items stay constant for the whole horizon and does not automatically model inflation, interest earned on the balance, or pay rises. It is a short-to-medium-term liquidity planner, not a long-horizon investment model — for multi-year wealth questions, use FiMo's compound interest or savings goal tools.
Worked example: 50.000.000 VND starting balance, 12-month horizon
Illustrative assumptions: 30.000.000 VND/month salary, 8.000.000 VND/month rent, 12.000.000 VND/month living costs. One-time events: a 40.000.000 VND Tet bonus in month 2 and 25.000.000 VND of tuition in month 6.
The fixed recurring net flow each month = 30.000.000 − 20.000.000 = 10.000.000 VND.
| Month | Income | Expenses | Net flow | Closing balance |
|---|---|---|---|---|
| 1 | 30.000.000 | 20.000.000 | 10.000.000 | 60.000.000 |
| 2 (Tet bonus) | 70.000.000 | 20.000.000 | 50.000.000 | 110.000.000 |
| 5 | 30.000.000 | 20.000.000 | 10.000.000 | 140.000.000 |
| 6 (tuition) | 30.000.000 | 45.000.000 | -15.000.000 | 125.000.000 |
| 12 | 30.000.000 | 20.000.000 | 10.000.000 | 185.000.000 |
Reading it: month 2 income jumps to 70.000.000 VND on the Tet bonus, lifting the balance to 110.000.000 VND. Month 6 is the only month with a negative net flow (-15.000.000 VND) because the 25.000.000 VND tuition outweighs the fixed recurring surplus — yet the balance still holds at 125.000.000 VND, so nothing breaks. The three summary metrics:
| Metric | Value |
|---|---|
| Final balance (month 12) | 185.000.000 VND |
| Minimum cash reserve | 50.000.000 VND |
| Total net flow over horizon | 135.000.000 VND |
Note that the total net flow of 135.000.000 VND equals the final balance 185.000.000 VND minus the 50.000.000 VND you started with — the built-in cross-check.
When a plan breaks: a liquidity-warning example
Keep the same recurring flows but cut the starting balance to 5.000.000 VND and front-load two big costs: a 30.000.000 VND car deposit in month 1 and 25.000.000 VND of tuition in month 2 — both before any bonus arrives.
| Month | Net flow | Closing balance |
|---|---|---|
| 1 (car deposit) | -20.000.000 | -15.000.000 |
| 2 (tuition) | -15.000.000 | -30.000.000 |
The balance bottoms out at -30.000.000 VND and is negative for 4 months (starting in month 1). That is exactly the warning the tool raises. The fix is usually not earning more — it is rescheduling: push the car deposit to a month after the bonus lands and the minimum reserve can swing back above zero with no change to the annual total.
Frequently asked questions
How is cash flow different from profit or income?
Profit (or annual net income) is a single summary figure; cash flow shows money moving in and out at each point in time. You can finish the year ahead and still run short in the exact month a tuition bill lands. In the illustrative example the total net flow for the year is 135.000.000 VND (positive), yet month 6 alone has a negative net flow of 15.000.000 VND because of tuition. This tool tracks the timing that a year-end total hides.
What does "minimum cash reserve" mean and why does it matter?
It is the lowest closing balance across the entire horizon. It matters more than the final balance because if it is negative you run short of cash at some point even when the yearly total is positive. In the healthy example the final balance is 185.000.000 VND and the minimum reserve is 50.000.000 VND (still positive). In the warning example the minimum reserve drops to -30.000.000 VND — the moment the plan breaks.
How many months should I project?
The tool offers 3, 6, 12, 18 or 24 months. The practical rule: choose a horizon long enough to cover the big events you already know about. If your Tet bonus and your tuition bill are almost a year apart, project at least 12 months. The further out you go, the less reliable the "constant recurring flows" assumption becomes, so 12 months is usually a good balance for personal planning.
What is the difference between a recurring item and a one-time event?
A recurring item occurs in every month: salary of 30.000.000 VND, rent of 8.000.000 VND, living costs of 12.000.000 VND. A one-time event lands in exactly one month you choose: a 40.000.000 VND Tet bonus in month 2, 25.000.000 VND tuition in month 6. Classifying these correctly is what makes the projection accurate — assigning a large event to the wrong month shifts the entire minimum-reserve point.
The tool says my balance goes negative — what should I do?
First, do not just look at the annual total. In the warning example (a 5.000.000 VND starting balance with a car deposit and tuition front-loaded), the balance is negative for 4 months even though the year's total net flow is positive. Three fixes: (1) reschedule the large outflow to after a bonus arrives — often enough on its own; (2) raise the starting balance from an emergency fund; (3) trim recurring costs. Drag the event to a later month in the tool to see the effect immediately.
Does the tool add interest on the balance or adjust for inflation?
No. This is a short-to-medium-term liquidity planner: it assumes recurring flows stay constant, and it does not earn interest on the balance, subtract inflation, or grow your salary. For multi-year, compounding wealth questions use FiMo's Compound Interest or Savings Goal tools; to see purchasing power in real terms, use the Inflation calculator.
How is total net flow calculated and how do I verify it?
Total net flow = total income over the horizon − total expenses over the horizon, and it always equals (final balance − starting balance). In the example: 185.000.000 VND − 50.000.000 VND = 135.000.000 VND. If those two calculations disagree, an item was entered incorrectly — it is the quickest way to sanity-check the projection.