Investing in exchange-traded funds (ETFs) can be a helpful way to build long-term wealth. But deciding how much to invest (and when) deserves some thought. Because there’s no one-size-fits-all approach.

The “right” number will look different for everyone. It depends on your priorities, your financial situation, and how much risk you’re willing to accept. Figuring out how much to invest each month starts with knowing what you’re working towards and what you can comfortably set aside. You might prefer a regular amount, or adjust it as things change. Either way, consistency can play a big role over time.

This article won’t give you a set number. Instead, it’ll guide you through the questions to help you decide for yourself.

Recap: what is an ETF?

An ETF is a type of investment you can buy and sell on the stock market, just like a share.

But here’s the key difference: instead of giving you exposure to one company, an ETF holds a collection of investments. That might include shares, bonds, property or other assets. So, with a single trade, you can invest in a whole mix.

Most ETFs track a specific index . For example, some aim to track the top 200 companies listed on the Australian Securities Exchange (ASX) . Others focus on global markets or particular sectors.

This approach can make investing more accessible. You don’t have to pick individual shares or research every company. That’s one reason why ETFs are popular among long-term investors. They can offer a way to diversify and simplify a portfolio without needing to manage each part.

Of course, like all investments, ETFs carry risk, and they can rise and fall in value. With that said, they can be a useful tool when used with a clear plan and and suitable risk tolerance.

If you decide ETFs are right for your goals, the next question is how much to invest so you can get there.

Questions to help you find your number

There’s no fixed rule for how much to invest in ETFs each month. But there are some useful questions to ask yourself. These questions won’t give you a final answer, but they can help you get clear on your goals, needs and limits.

You don’t need to have everything worked out, but taking the time to reflect can make your decision more grounded.

Let’s go through them, one by one.

1. Do you even want to invest in ETFs right now?

Before you think about how much to invest, ask yourself this: do you actually want to invest in ETFs at the moment?

You might be weighing up your options. That could include high-interest savings , paying off debt , or saving for a home . These can all be valid goals too.

Or maybe you’re not ready to invest yet. That’s okay. It’s common to focus on financial stability first, especially if your situation is changing or uncertain.

You might already know that investing is part of your long-term plan, but you’re not sure where to start. Whatever the case, it’s about checking in before you commit to regular investing.

There’s no right or wrong answer here. Just a reminder to choose based on your goals, not what you feel you “should” be doing.

2. Do you have an emergency fund in place?

Before setting money aside for investing, think about whether you’ve built a basic financial buffer.

An emergency fund doesn’t need to cover every scenario; it just needs to give you room to move when things don’t go to plan.

Here’s what that might look like:

• What it’s for: A stash of money set aside for unexpected expenses like car repairs, medical bills, or job loss.
• How much to aim for: Many people save three to six months of essential costs — think rent, groceries, bills and transport.
• Does it need to be exact? Not at all. What matters is having enough to feel steady if your income drops or stops.
• Why it matters for ETF investing: ETFs are built for the long term. You can sell them, but prices can dip, sometimes when you least expect it.
• The risk of needing that money fast: Selling during a downturn might mean withdrawing less than you put in.
• How an emergency fund helps: It gives you flexibility. Your investments can stay invested, even when life throws something unexpected your way.

3. Do you have a monthly budget or spending plan?

A simple way to work out how much to invest is to start with your budget .

Your budget shows what comes in, what goes out, and what’s left over. That leftover amount — your surplus — is where investing can begin. If you haven’t created a budget yet, now could be a good time. It doesn’t need to be complicated to be useful.

Some people use the “pay yourself first” approach. That means setting money aside for goals, like investing , before spending on other things.

If your budget allows for it, this can help build momentum. It turns investing into a regular habit, not a once-off task. Even a small monthly amount can make a difference over time. It’s less about the number and more about the consistency.

The goal here isn’t perfection, it’s clarity.

4. How steady is your income and spending?

Your income and spending patterns can shape how you approach ETF investing. Some people earn the same amount each month, but that’s not the case for everyone.

If your income changes often, you might prefer to stay flexible. That could mean investing more in some months and less in others. A steady income, meanwhile, may make it easier to automate a regular investment amount. It keeps things consistent.

But income is only part of the picture. Your expenses, any existing debt, and how secure your job feels also play a role.

If your financial situation changes often, locking in a set amount might feel uncomfortable. That’s completely reasonable. What matters is choosing an approach that suits your circumstances.

5. How much risk are you comfortable taking?

ETF investing, even with a long-term view, involves some risk. Markets can go up, but they can also go down. How would you react if your investment dropped in value? Would you stay invested or feel the urge to pull out?

Understand your risk tolerance — whether you’d feel okay riding out the lows or would prefer to take a more cautious path. This can help shape your investing strategy , especially how much you contribute and how often.

You might choose to start small and build confidence over time. Or, you might be happy investing more from the start. It’s about making a choice that feels manageable not just on the good days, but when things get rocky too.

6. How do you feel about investing small vs investing lump sums?

Think about how you prefer to invest. Do you like the idea of saving first, then making a larger investment when it feels right? Or would you rather invest smaller amounts more often, no matter what the market’s doing?

Both approaches are valid. Here’s a quick breakdown:

Lump sum investing

• With lump sum investing , you save up first then invest a larger amount when you feel ready.
• Your money gets invested straight away, which can help if markets are rising.
• But it also means taking on more risk upfront, especially if markets fall soon after.

Investing smaller amounts regularly

• You invest a set amount weekly, fortnightly, or monthly, regardless of market conditions.
• This is often called dollar-cost averaging . It means buying at different prices over time.
• It can help reduce the impact of short-term market swings, but it doesn’t protect against losses.

You might even mix both approaches — starting small, then adding more when you feel ready. What’s most useful is picking a routine you’re likely to stick with. Consistency can sometimes matter more than timing.

7. What are your other short- and medium-term goals?

Before locking in a monthly ETF amount, take a step back. What else are you saving for over the next few years?

You might be working towards a car, a home deposit , a holiday, or something more personal — like starting a business or planning a wedding.

If you’re contributing to the First Home Super Saver Scheme (FHSS) , that’s worth factoring in. It lets you save for a home deposit inside your super fund, with potential tax benefits.

Just keep in mind that FHSS savings are separate from your ETF portfolio, and each has different timeframes and access rules.

When money’s limited (and it often is), it helps to prioritise. Which goals are most important to you right now? Which ones can wait? You don’t need to have it all figured out. But knowing your priorities can make it easier to decide how much to invest — and where.

8. Are you working toward Financial Independence (or another target)?

You might have a specific goal in mind — like reaching Financial Independence , retiring early, or covering future living costs with investments. If so, setting a clear target can help. One example is the Financial Independence, Retire Early (FIRE) approach.

A common method used by people on the FIRE path is calculating a “ FI number .” That’s the amount you’ll need to support your annual expenses in retirement.

A rough formula is: FI number = annual living expenses × 25

So, if you spend $80,000 per year, your FI number might be around $2 million.

This estimate is based on the idea that you could safely withdraw 4% of your portfolio each year without running out of money too soon. And if you don’t feel up to calculating it yourself, try Pearler’s Financial Independence Calculator .

Once you’ve got a number in mind, you can work backwards. How many years until your target? How much could you invest each month to get there?

While this won’t give you an exact answer, it can help give your investing plan some structure. And that can be motivating.

Of course, your plans may change over time. But having a goal (even a loose one) can help guide your decisions today.

So, how do you settle on a monthly ETF investment amount?

As we’ve said, the amount you invest depends on your income, expenses, goals, and how comfortable you are with risk. Figure out your short-term priorities, income stability, and financial buffers — it all connects.

You might land on a number that feels right for now, but things change. Life isn’t always linear. So, keep it flexible. You can adjust your monthly amount as your circumstances evolve. That doesn’t mean you’ve made a mistake.

You also don’t need to start big. It simply helps to build a habit that works for your current circumstances. Once you're in a rhythm, it becomes easier to review, tweak and track portfolio progress .

The right amount isn’t about being exact. It’s about being thoughtful — and allowing yourself to keep learning as you go.

When in doubt, seek professional guidance

There’s a lot to consider when it comes to investing, especially when you’re working out what fits into your life right now. If you're feeling stuck, it might help to chat with a licensed financial adviser . They can offer support that's tailored to your goals and circumstances, not someone else's.

But when it comes to choosing your number — that’s your call. And it’s okay if it takes a little while to figure out.

You don’t need a crystal-clear plan before you start. What matters is that you’ve taken the time to think it through. So ask the questions, explore the options, and make a start when you’re ready.