Data Source and Methodology

Contribution growth is modelled using standard future value of an annuity formulas. Withdrawal estimates rely on the inflation-adjusted annuity formula recommended by the UK MoneyHelper pension calculator and US CFP® guidance for sustainable drawdown ranges (3%–5% real).

All calculations are strictly based on the formulas and data provided by these sources.

Key Formulas

Glossary

• Net return: Gross return minus annual fees.
• Contribution frequency: How often you deposit into the pension.
• Inflation assumption: Used to translate future values into today’s money.
• Withdrawal horizon: Number of years you expect the pension to last in retirement.

Frequently Asked Questions

How realistic are the return assumptions?

Use long-term average returns for your asset mix, then subtract the total expense ratio of your pension funds to estimate net return.

Can I model a lump-sum withdrawal?

Yes. Set the payout horizon to 1–5 years and review the monthly income figure—it represents the fixed payment needed to spend down the pot.

How should I treat employer contributions?

Add the expected employer match per contribution period. The calculator treats it as additional, guaranteed deposits.

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FV_{\text{contrib}} = P \times \frac{(1 + i)^{n} - 1}{i}

FV_{\text{total}} = B_0 (1 + r_{\text{net}})^t + FV_{\text{contrib}}

W = \frac{FV_{\text{real}} \times r_{\text{real}}/12}{1 - (1 + r_{\text{real}}/12)^{-12y}}

Future value of contributions \[ FV_{\text{contrib}} = P \times \frac{(1 + i)^{n} - 1}{i} \] Total balance \[ FV_{\text{total}} = B_0 (1 + r_{\text{net}})^t + FV_{\text{contrib}} \] Inflation-adjusted monthly income \[ W = \frac{FV_{\text{real}} \times r_{\text{real}}/12}{1 - (1 + r_{\text{real}}/12)^{-12y}} \]