Decision Tools: Compare Two Choices

How these tools work

Both choices start with the same money, so the comparison is like for like.
Each result is split into the money put in and what it grew to, or what it cost, so the parts add up to the figure shown.
The rates you enter are held constant every year, and each page shows how the result changes when they change.
Neither tool says which choice to make. They show modeled money, with a link that reopens the exact result.

Common questions

What do the decision tools compare?

Two ways to use the same money: buying a home or renting a similar one, and keeping money in a savings account or investing it. Each tool shows what both choices would leave under the assumptions you enter.

Do the decision tools say which choice to make?

No. They compare modeled money only. Things a calculator can't weigh, such as stability, flexibility or how quickly the money can be reached, are left to you.

How does the result change with the rates I enter?

Both tools hold the rates you enter constant every year, and small differences add up over many years. Each page has a table showing how the result changes when the main rates change.

Can I check the numbers myself?

Yes. Each calculator page has a section on how the result is calculated, and a link that reopens the page with the inputs behind the example result, so you can reproduce it by hand or in the tool.