Retirement Withdrawal Calculator (4% Rule, VND)
Whether you are building a FIRE portfolio or planning a conventional retirement in Vietnam, the hardest number is not how much to save — it is how much you can safely withdraw each year without running out of money. The classic answer is the 4% rule, which comes from the Trinity study (Cooley, Hubbard & Walz, 1998): in year one of retirement, withdraw about 4% of your portfolio, then adjust that amount for inflation each year. Across historical US market windows, a balanced stock/bond portfolio survived a 30-year retirement at this rate with a very high success rate.
For a portfolio of 5,000,000,000 VND under an illustrative 4%/year assumption, that is roughly 200.000.000 VND per year — about 16.666.667 VND per month of self-funded income. Read the other way, the 4% rule is the 25x rule: to fund a given annual spend, you need a nest egg of roughly 25 times that spend. Spending 30.000.000 VND/month (360.000.000 VND/year) implies a portfolio near 9.000.000.000 VND.
The calculator above works both directions: enter a nest egg to see the sustainable annual and monthly withdrawal, or enter a target monthly spend to see the portfolio required. One firm caveat applies to everything here: 4% is a rule of thumb, not a guarantee. It is built on historical US data; VND inflation, local taxes and a Vietnam-weighted portfolio can behave differently. Treat the output as a planning starting point, not a promise of lifelong income.
How the 4% rule works and how this calculator computes it
The withdrawal formula
The first-year safe withdrawal is:
Annual withdrawal = Nest egg × Safe withdrawal rate (SWR)
| Symbol | Meaning |
|---|---|
| Nest egg | Total portfolio value at the start of retirement |
| SWR | Safe withdrawal rate as a percent (default 4%) |
| Annual withdrawal | Year-one withdrawal (later years add inflation) |
| Monthly withdrawal | Annual withdrawal ÷ 12 |
Verifiable example: 5,000,000,000 × 4% = 200.000.000 VND/year, divided by 12 gives 16.666.667 VND/month.
The inverse — how big a portfolio do you need?
Nest egg needed = Desired annual spending ÷ SWR
This is the 25x rule (since 1 ÷ 4% = 25): to withdraw X per year you need 25·X invested. Spending 30.000.000 VND/month = 360.000.000 VND/year → 360.000.000 ÷ 0.04 = 9.000.000.000 VND.
Why 4%?
The Trinity study tested every rolling 30-year window in US market history and found that a balanced stock/bond portfolio, withdrawing 4% in year one and rising with inflation, almost never depleted within 30 years. The 4% figure is conservative, not optimal — in many historical windows the portfolio actually grew.
What the model leaves out
- Sequence-of-returns risk: a sharp market drop in the first few retirement years, while you are still withdrawing, erodes capital far faster than an average return suggests. This is the single biggest risk that a static percentage hides.
- The ~30-year horizon: early retirees who need 40–50 years of income often drop to 3–3.5%.
- Vietnam context: 4% is calibrated to US data. VND inflation, taxes and portfolio composition differ, so adjust conservatively and review the plan periodically.
Worked example: a 5,000,000,000 VND nest egg at 3% / 3.5% / 4%
Illustrative assumptions: a first-year withdrawal at the stated rate, later years adjusted for inflation (not shown), a balanced stock/bond portfolio.
| SWR | Safe withdrawal/year | Safe withdrawal/month | Profile |
|---|---|---|---|
| 3.0% | 150.000.000 | 12.500.000 | Very conservative, fits 40–50yr FIRE |
| 3.5% | 175.000.000 | 14.583.333 | Middle ground |
| 4.0% | 200.000.000 | 16.666.667 | Original 4% rule (~30 years) |
Cutting from 4% to 3% lowers the draw from 200.000.000 to 150.000.000 VND/year — 50.000.000 VND less — in exchange for a much larger safety buffer, which matters most if you retire early.
Inverse example: what portfolio funds 30.000.000 VND/month?
Desired spending 30.000.000 VND/month = 360.000.000 VND/year.
| SWR | Nest egg needed (25× rule) |
|---|---|
| 3.0% | 12.000.000.000 |
| 3.5% | 10.285.714.286 |
| 4.0% | 9.000.000.000 |
For the same 30.000.000 VND/month, choosing the safer 3% rate requires 12.000.000.000 VND — 3.000.000.000 VND more than the 9.000.000.000 VND implied by the 4% rule. That gap is the price of a wider safety margin. If you are still accumulating toward this number, pair this tool with FiMo's compound interest and savings goal calculators to size the monthly contribution required.
Frequently asked questions
What is the 4% rule for retirement?
The 4% rule comes from the Trinity study: in year one of retirement, withdraw about 4% of your portfolio, then adjust that amount for inflation each year. On a 5,000,000,000 VND portfolio at an illustrative 4%/year, that is 200.000.000 VND/year (~16.666.667 VND/month). It is a rule of thumb, not a guarantee — based on historical US market data.
How much can I withdraw monthly from a 5 billion VND nest egg?
Under the 4% rule (illustrative 4%/year): 5B × 4% = 200.000.000 VND/year, about 16.666.667 VND/month. A more conservative 3.5% gives 14.583.333 VND/month, and 3% gives 12.500.000 VND/month. The lower the rate, the longer the portfolio is likely to last.
How big a portfolio do I need to spend 30 million VND a month?
Spending 30.000.000 VND/month = 360.000.000 VND/year. Under the 4% (25x) rule you need 360.000.000 ÷ 0.04 = 9.000.000.000 VND. For a safer 3% withdrawal you would need 12.000.000.000 VND. These figures are illustrative — actual VND inflation can change the plan.
What is the 25x rule?
The 25x rule is just the 4% rule restated (since 1 ÷ 4% = 25): to withdraw X per year you need 25 times X invested. To spend 360.000.000 VND/year you need 25 × 360.000.000 = 9.000.000.000 VND. FIRE planners use it as a quick target for the portfolio size to aim for.
Does the 4% rule still hold for early retirement (FIRE)?
The 4% rule was validated for a ~30-year horizon. If you retire early and need 40–50 years of income, many experts suggest dropping to 3–3.5% for a wider safety margin. On a 5B VND portfolio that is the difference between 200.000.000 VND/year (4%) and 150.000.000 VND/year (3%). Match the rate to how long the portfolio must last.
What is sequence-of-returns risk?
It is the risk of a sharp market downturn in the first few years of retirement. Because you are still withdrawing to live while the portfolio is falling, capital erodes far faster than an average return implies. Two retirees with the same average return but different orderings of good and bad years can end up very differently — which is exactly why 4% is set conservatively.
Does the 4% rule apply in Vietnam?
Use it cautiously. 4% is calibrated to historical US markets; VND inflation, local taxes and portfolio composition can differ. Treat it as a planning starting point, lean toward a lower withdrawal rate if most of your portfolio is VND-denominated, and review the plan periodically. This tool does not replace personalised financial advice.