Compound growth of high-yield savings over time.

High-yield savings accounts pay materially higher interest than standard current accounts — typically 4-6% currently (vs 0-1% on standard accounts). Over multi-year periods, the compound difference is meaningful. 10,000 at 5% for 10 years becomes 16,470 — a 6,470 gain just from choosing a better rate.

The calculation uses monthly compounding (standard for savings accounts). Each month, interest is calculated on the current balance and added. New contributions further increase the base. Over years, the combination of interest on existing balance and ongoing contributions compounds meaningfully.

Key factors affecting the outcomestarting balance (larger base → more absolute growth), contribution size (steady contributions compound powerfully over time), interest rate (small rate differences produce large differences over time), time horizon (the non-linear part — compound growth accelerates at longer horizons).

How to use it

Input starting balance, monthly contribution (zero if not adding), annual interest rate (current best rates), and years. The tool shows projected balance, total contributed, and interest earned.

What the result means

Projected balance is the end-of-period total. Total contributed is what you put in (starting + monthly × 12 × years). Interest earned is the balance minus contributed — this is the money that works for you rather than being work you did.

Savings projection tool. Actual rates change; check current offers. Not financial advice.

Run it with sensible defaults

Using starting balance of 10,000, monthly contribution of 200, annual interest rate of 5%, time horizon of 10, the calculation works out to 47,526.55. Nudge the inputs toward your own situation and the output recalculates instantly. The defaults are meant as a starting point, not a recommendation.

The levers in this calculation

The inputs — Starting Balance, Monthly Contribution, Annual Interest Rate, and Time Horizon — do not pull with equal force. Not every input has equal weight. Flip one at a time toward extreme values to feel which ones move the needle most for your situation.

How the math works

Monthly compounding with regular contributions. Combines future value of lump sum and future value of annuity formulas. The working is transparent — you can verify every step yourself in the formula section below. No black box, no opaque "proprietary model".

How to use this beyond the first run

Re-run the calculation once a year. Life changes — pay rises, new expenses, interest-rate shifts — and the figure that looked right 12 months ago often isn't today. Annual recalibration keeps the plan honest.

What this doesn't capture

The calculation assumes a steady savings rate and a stable interest rate. Real saving journeys include emergencies, windfalls, and rate changes — especially in easy-access products. The figure is a direction of travel, not a guarantee.