What Is Coast FI? How to Work Out Your Coast FI Number in Singapore

Coast FI: the maths, step by step

Wei Ling is 30, and she has done the scary version of the retirement maths more than once. A big number at 65, a long list of years in between, and the quiet feeling of being behind. (Wei Ling is made up, but you probably know her.)

Then a friend asks her a different question: forget the big number for a second. How much would need to be invested today so that she never has to add another dollar for retirement?

That number has a name. It's called Coast FI, and once you see how it works, the whole retirement conversation gets less scary.

What Coast FI means

Coast FI is the amount you need invested today so that, without adding anything more, it can grow into your full retirement pot by the age you choose to stop working.

The name comes from cycling. You've pedalled up the hill. From here, you can coast down. You still steer, and you still work and pay today's bills. You just stop having to put more away for later. Anything extra you save after that point is a bonus, or room to slow down.

It's different from early retirement. Nobody quits. Coast FI is a checkpoint along the way, and for most people it comes a lot earlier than the finish line.

Why the idea exists

Most retirement planning starts at the end: how much will I need at 65? That number is usually large enough to make people stop reading.

Coast FI starts from today instead, and it gives time the credit it deserves. Money saved early has decades to grow, and growth builds on growth. A dollar put away at 30 does far more work than a dollar put away at 50.

In Singapore there's another reason it fits. CPF LIFE pays a monthly income for life, starting any time from 65 to 70, so your own savings don't have to cover everything. If you defer payouts, they rise by up to 7% for each year you wait, and by up to 35% if you start at 70.

The maths, step by step

There are three steps. We'll use one example all the way through.

Step 1: The income you want. Pick the yearly income you'd want from your own savings. For our example, we used Singapore's 2025 median gross monthly income from work for full-time employed residents: $5,775 a month (MOM, including employer CPF). That's $69,300 a year. CPF LIFE then sits on top as a bonus.

Step 2: The pot that pays it. Divide that yearly income by how much you plan to take out each year. A common rule is 4%.

$69,300 ÷ 4% = $1,732,500

Dividing by 4% is the same as multiplying by 25, which is where the "× 25" you may have seen comes from.

The 4% comes from William Bengen's 1994 study of US market history. He tested a portfolio of half US stocks and half US Treasury bonds. Taking out 4% in the first year, then raising the amount with inflation every year, never ran a portfolio dry in under 33 years in any past period he tested. Most lasted 50 years or more.

Step 3: Work backwards to today. Now ask how much money, left alone, grows into that pot by the time you stop working.

Coast number = pot ÷ (1 + growth rate)^years left

Example: you're 30, you want to stop at 65, and you assume 5% growth a year after inflation. Over 35 years, $1 grows to about $5.52.

$1,732,500 ÷ 5.52 ≈ $314,000

To check it the other way: $314,000 × 5.52 ≈ $1.73 million.

So in this example, about $314,000 invested at 30 could grow into the full pot by 65 without another dollar added. That's Coast FI.

The growth rate does most of the work

The rate you plug in changes the answer more than anything else. Same $1.73 million target, same 35 years:

Two things to notice.

Use growth after inflation. Your target is in today's dollars, so the growth rate has to be too. US stocks returned about 10% a year from 1928 to 2025 before inflation, and about 6.8% after it. If you plug in 10% without raising your target for inflation, you'll get a number that looks far too small.

Higher growth usually comes with bigger drops. A stock-heavy mix has done better over long stretches of history, but it has also fallen hard in some years. A cautious rate gives you a bigger number and fewer surprises.

Not there yet? Pick a later age

Most people reading this won't be at their Coast number today, and that's normal. The useful move is to run the same maths for a later age and see what you'd need by then.

Same target, 5% a year, stopping at 65:

The number rises each year you wait, because there's less time left for growth to do the work.

You can also move the other end. Working to 70 instead of 65 gives your money five more years to grow. Hit it at 40 but plan to work to 70, and the number drops from about $512,000 to about $401,000.

Try it yourself: a 10-minute self-check

Here's the whole thing as a self-check, with a made-up example.

1. Write down the yearly income you'd want from your own savings. Ravi (made up) is 35 and wants $3,000 a month on top of CPF LIFE. That's $36,000 a year.
2. Multiply by 25. $36,000 × 25 = $900,000. That's his full pot.
3. Pick the age you'd like to stop, and count the years left. Ravi picks 65, so 30 years.
4. Pick a growth rate after inflation, and be honest with yourself. Ravi uses 5%. Over 30 years, $1 grows to about $4.32.
5. Divide. $900,000 ÷ 4.32 ≈ $208,000. That's Ravi's Coast number today.
6. Compare it with what you already have invested for retirement. Ravi has about $120,000. He isn't there yet.
7. Run it for a later age. If Ravi aims to reach Coast by 40, he'd need about $266,000 by then. Left alone at 5%, his $120,000 would grow to about $153,000 by 40, so the gap is what he'd need to add over the next five years.

The exercise swaps a vague worry for a rough, specific number you can track.

Want to play with your own numbers? Try our free Coast FI Calculator — it does the maths for you, and nothing you enter is stored or sent anywhere.

Where to get help

Some honest caveats

• Growth isn't guaranteed. Markets fall hard some years, and a Coast number assumes the money is left alone through all of it.
• The 4% rule comes from US history and a 30-year retirement. Singapore markets, a longer retirement or different investments can give a different answer.
• Your spending and plans will change. Health costs, family and where you live all move the target, so the number moves too. Rerun it every few years.
• The median income is just an example. It includes employer CPF, and plenty of people will need more or less than that in retirement.
• If saving anything feels hard right now, that's okay. Coast FI is a map for later.

Our 5 cents

For most of us, Coast FI is a calmer and more reachable goal than early retirement. You keep working, and once you're there, saving more is a choice instead of a pressure.

A few questions worth sitting with:

• What yearly income would you want from your own savings, on top of CPF LIFE?
• What growth rate, after inflation, would you honestly be comfortable assuming?
• By what age would you like the choice to ease off?

This post is our opinion and general commentary, not financial advice. We are not licensed financial advisers. Everyone's circumstances are different — please speak to a MAS-licensed adviser before making any financial decisions.

Sources

• MOM: Labour Force in Singapore Advance Release 2025 (median gross monthly income, $5,775 including employer CPF)
• CPF: What is the CPF LIFE payout age?
• CPF: PLAN with CPF
• CPF: What is the Monthly Payout Estimator?
• W. P. Bengen: Determining Withdrawal Rates Using Historical Data, Journal of Financial Planning (October 1994, FPA reprint)
• A. Damodaran, NYU Stern: Historical returns on stocks, bonds and bills, 1928 to 2025
• MoneySense: Financial advice: who you could be dealing with