How it is calculated
- Balance at retirement = growth of current savings + growth of monthly contributions until retirement at the expected return.
- Sustainable income: the payment that runs the balance down over your retirement years at a more cautious post-retirement return.
- Target: the balance needed to fund your desired income (inflated to future value) for all retirement years.
Add any state or employer pension on top.
Worked example
Age 35, retiring at 63 with 50,000 saved and 1,500 a month at 6%: about 1.52 million at retirement, enough to draw roughly 8,400 a month for 20 years at 3%.
Frequently asked questions
What is the 4% rule?
A rule of thumb that withdrawing 4% a year, adjusted for inflation, usually makes savings last about 30 years.
Should I include my state pension?
Yes — enter it as “expected pension” and it is deducted from what your savings must provide.
What return is realistic?
Balanced long-term portfolios have historically earned roughly 5–7% a year before inflation, with no guarantee.