How This Retirement Calculator Works

We compound today’s savings and future contributions until retirement, discounting results by your inflation assumption. During retirement, we estimate sustainable withdrawals using a real return (post-retirement return minus inflation).

Key Formulas

How to Use

1. Enter your current age, planned retirement age, and years you expect to spend in retirement.
2. Add today’s savings, monthly contribution, and any employer contribution.
3. Set return assumptions and inflation. We use them to grow balances and convert to real pounds.
4. Provide your desired annual income (today’s pounds) and estimated Social Security or defined-benefit income.
5. Review projected nest egg, sustainable withdrawals, total income, and the contribution needed to close any gap.

Frequently Asked Questions

Does this include taxes?

No. Results are pre-tax. Adjust for your effective tax rate or consult a financial professional.

How often should I revisit my plan?

Review at least annually or whenever your income, contributions, or goals change significantly.

What if my employer match changes?

Update the employer contribution field to see how it affects your projected nest egg and suggested savings.

What assumptions does the sensitivity table use?

It varies the pre-retirement return by ±1% while holding other inputs constant to show how sensitive your nest egg is to market returns.

FV_{\text{savings}} = P_0 (1 + r_{\text{pre}})^{T}

FV_{\text{contrib}} = \begin{cases} C \cdot \dfrac{(1+i)^{n}-1}{i}, & i \ne 0 \\ C \cdot n, & i = 0 \end{cases}

W = \begin{cases} \dfrac{FV_{\text{real}} \cdot r_{\text{real}}}{1-(1+r_{\text{real}})^{-N}}, & r_{\text{real}} \ne 0 \\\\[6pt] \dfrac{FV_{\text{real}}}{N}, & r_{\text{real}} = 0 \end{cases}

Future value of current savings \[ FV_{\text{savings}} = P_0 (1 + r_{\text{pre}})^{T} \] Future value of monthly contributions (with employer match) \[ FV_{\text{contrib}} = \begin{cases} C \cdot \dfrac{(1+i)^{n}-1}{i}, & i \ne 0 \\ C \cdot n, & i = 0 \end{cases} \] where \(C\) is total monthly contribution and \(i\) the monthly return. Sustainable real withdrawal (monthly) over \(N\) months \[ W = \begin{cases} \dfrac{FV_{\text{real}} \cdot r_{\text{real}}}{1-(1+r_{\text{real}})^{-N}}, & r_{\text{real}} \ne 0 \\\\[6pt] \dfrac{FV_{\text{real}}}{N}, & r_{\text{real}} = 0 \end{cases} \]