Mortgage Payoff vs Invest

Should you overpay your mortgage or invest the surplus? See the real numbers side by side.

Mortgage balance

Interest rate (%)

Remaining term (years)

Monthly extra (£)

Investment CAGR (%)

Comparison horizon (yrs)

📈

Investing wins

Over 25 years with £500/month

Interest saved by overpaying

£70,831

Investment gain (after contributions)

£241,521

Break-even year

Year 1

🏠

Overpay Mortgage

Guaranteed return = your mortgage rate

Total overpaid£150,000

Interest saved£70,831

Mortgage cleared in16 years

Net benefit£161,709

📈

Invest Instead

Projected at 7% CAGR

Total invested£150,000

Portfolio value£391,521

Investment gain£241,521

Net benefit£241,521

Interest Saved vs Investment Gain Over Time

Yr 5

£4k

£6k

Yr 10

£16k

£26k

Yr 15

£38k

£66k

Yr 20

£62k

£134k

Yr 25

£71k

£242k

Interest saved (overpay)

Investment gain

Year-by-Year Breakdown

Year	Mortgage Left	Interest Saved	Investment Value	Inv. Gain	Winner
1	£238,336	£125	£6,190	£190	Invest
5	£186,072	£3,573	£35,598	£5,598	Invest
10	£106,047	£15,599	£85,526	£25,526	Invest
15	£5,872	£38,207	£155,552	£65,552	Invest
20	£0	£61,993	£253,768	£133,768	Invest
25	£0	£70,831	£391,521	£241,521	Invest

⚠️ Illustrative projections only — not financial or legal advice. Consult a qualified adviser before making financial decisions.