How long does it take to save £100k at £500 a month?

From zero, it takes about 12 years at a 5% annual return, 11 years at 7%, and just over 10 years at 9%. A £10,000 starting balance cuts roughly 1.5 to 2 years.

Does the starting balance matter more than the return rate?

Time matters more than either. The longer the money is invested, the more compounding works. A starting balance helps because it has longer to grow, but regular contributions do most of the heavy lifting.

Where should I keep the money in the UK?

A Stocks and Shares ISA is a common choice because income and gains are tax-free. A SIPP gives tax relief on contributions but locks money away until the normal minimum access age. Your choice depends on when you need the money.

Can I really earn 7% a year?

7% is a long-term average figure often used for diversified equity portfolios. Actual returns vary year to year. Some years are negative, some are much higher. The projection is not a promise.

What if I increase my monthly contribution?

Every extra pound increases the final balance. Raising monthly contributions has a bigger effect than chasing a higher return, especially over shorter horizons.

No. Markets go down as well as up. The calculator uses a fixed rate to make planning simple. Real returns are not fixed.

UK articleUpdated 2 August 2026By Glenn Rodgers

How long does it take to save £100k?

Compound interest is the snowball effect of earning returns on your previous returns. This article estimates how long it takes to reach £100,000 from a regular monthly contribution and a steady investment growth rate, using the same method as the compound interest calculator.

TL;DR

Saving £500 a month from zero usually reaches £100k in about 10-12 years.
A £10,000 starting balance cuts roughly 1.5-2 years.
A 9% return is faster than 5%, but the monthly contribution matters more than the rate.
This is a projection, not a guarantee.

The short answer

There is no single answer. It depends on your starting balance, monthly contribution, and the return you earn. At £500 a month and no starting balance, the range is about 12 years at 5% to 10 years at 9%. A £10,000 head start brings the range down to about 10.5 years at 5% to 8.7 years at 9%.

Three scenarios: £500 a month at 5%, 7%, 9%

All three start from zero.

Starting amount	Monthly contribution	Annual return	Years to £100k	Total contributions
£0	£500	5%	~12.2 years	~£73,000
£0	£500	7%	~11.1 years	~£66,500
£0	£500	9%	~10.3 years	~£61,500

The table shows that a higher return helps, but most of the pot still comes from your own contributions. At 9% you pay in about £61,500 to get £100,000. At 5% you pay in about £73,000.

What if you start with £10,000?

A starting balance reduces the time because it has longer to compound.

Starting amount	Monthly contribution	Annual return	Years to £100k	Total contributions
£10,000	£500	5%	~10.6 years	~£73,500
£10,000	£500	7%	~9.5 years	~£67,000
£10,000	£500	9%	~8.7 years	~£62,000

The £10,000 head start saves roughly one and a half to two years. In a UK context, that £10,000 could sit in a Stocks and Shares ISA, a SIPP, or a general investment account. The wrapper changes the tax treatment but does not change the compound maths.

How to use the calculator

Open the UK compound interest calculator. Enter your starting balance, monthly contribution, expected return, and time horizon. The calculator shows the future balance, total contributions, and the growth from compounding.

If you want to know the exact time to reach £100,000, select the "Years" tab in the calculator, enter £100,000 as the target, and fill in the other inputs. The calculator will solve for the years required.

For a deeper explanation of the formula, see the UK compound interest guide. To track your net worth while you build the £100k, see the net worth tracker guide.

The formula is documented by the SEC at Investor.gov and by HMRC and the Bank of England in the context of UK savings and inflation.

FAQ

Frequently asked questions

How long does it take to save £100k at £500 a month?: From zero, it takes about 12 years at a 5% annual return, 11 years at 7%, and just over 10 years at 9%. A £10,000 starting balance cuts roughly 1.5 to 2 years.
Does the starting balance matter more than the return rate?: Time matters more than either. The longer the money is invested, the more compounding works. A starting balance helps because it has longer to grow, but regular contributions do most of the heavy lifting.
Where should I keep the money in the UK?: A Stocks and Shares ISA is a common choice because income and gains are tax-free. A SIPP gives tax relief on contributions but locks money away until the normal minimum access age. Your choice depends on when you need the money.
Can I really earn 7% a year?: 7% is a long-term average figure often used for diversified equity portfolios. Actual returns vary year to year. Some years are negative, some are much higher. The projection is not a promise.
What if I increase my monthly contribution?: Every extra pound increases the final balance. Raising monthly contributions has a bigger effect than chasing a higher return, especially over shorter horizons.
Is this guaranteed?: No. Markets go down as well as up. The calculator uses a fixed rate to make planning simple. Real returns are not fixed.

Last updated: 2026-08-10. This article is educational and is not financial advice.