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If you’ve ever Googled “how much should I invest per month?” you’ve probably gotten some version of the same answer: invest 15–20% of your income.

What if you’re 35 and already have $150,000 invested? What if you have $400,000 invested and want to work part-time at 50? What if you’re diligently investing 20%…but you’re also trying to have a baby and buy a house?

Suddenly, 15–20% doesn’t tell you very much.

Because how much you should invest each month has less to do with your salary and more to do with what you already have, what you want your money to make possible, and when you want it.

The goal isn’t to blindly invest as much as humanly possible until you’re 65. The goal is to know you’re doing enough for your future so you can actually enjoy your money and your life along the way.

PART 1: Stop Letting a Generic Percentage Plan Your Life

The standard advice to invest 15–20% of your income isn’t bad. When you’re just getting started, it can actually be incredibly useful.

Maybe you start by contributing enough to your 401(k) to get your employer match. As your income increases, you gradually increase your contribution. A percentage gives you a simple target when you don’t have much invested yet.

The problem is following that rule forever without ever asking what the money is actually supposed to do. I remember getting one of my first “big girl” paychecks in New York City and sitting down with my dad to go through it. I had a real job! Real money!

My salary was actually pretty low at the time, but whatever. Details. My dad showed me my pay stub and talked about how much I should save and invest. Totally normal, well-intentioned financial advice.

But something about it bothered me. The formula essentially started with: Here’s what you make. Therefore, here’s what you save. And eventually, here’s roughly the lifestyle you can afford. I wanted to flip that around.

What kind of life do I actually want? What will that life cost? And what do I need to do financially to make it possible?

If my income couldn’t fund it, fine. Give me a target. I could work toward a raise, change jobs, change careers, adjust the timeline or change the goal.But I didn’t want my current paycheck quietly deciding what the rest of my life got to look like. Your investing needs can change with your life This became even more important as I got older.

In my 20s, my income was growing and my expenses were relatively low. I didn’t know exactly what my 30s would look like, but I knew there was a good chance I’d want kids. I also suspected I wouldn’t want to stay in the same career forever.

So I invested aggressively. Not because investing the maximum amount forever was the goal, but because I wanted to buy future flexibility. Now, in my 30s with young kids, that flexibility matters a LOT more to me than bragging rights over my savings rate. I can invest less during this season because I invested more during another one.

Your investing rate does not have to stay exactly the same for 40 years. Your life isn't going to stay the same for 40 years either.

How Much Should I Invest Per Month Once I Already Have Money Invested?

This is where we graduate from the percentage rule. Start with four questions:

• How much do I already have invested?

• What am I actually trying to fund?

• When do I need the money?

• Which goals are non-negotiable, and which are nice-to-have?

And please actually add up your accounts. I see this constantly with clients. Someone has a current 401(k), an old 401(k), a Roth IRA, a brokerage account and cash somewhere else…and she has no idea what it all adds up to. She knows she’s been doing the “right” things, but she still has this low-level anxiety of: Am I actually doing enough?

You can’t answer that until you know where you’re starting. Think about what you want this money to make possible. Retirement? A house? Working part-time at 50? Taking a few years off with your kids? Paying for college? Traveling more?

The number only becomes meaningful when it’s attached to a life.

PART 2: Three Women, Three Completely Different Answers

Let’s make this real.

These three women all earn good money and already have substantial investments. But I’d give each of them a completely different answer to how much should I invest per month?

Monica: $150K invested and retirement at 65

Monica is 35, earns $125,000 per year and has $150,000 invested.

She wants to retire around 65 and estimates she’d like to spend about $80,000 per year in retirement. Using a rough 4% withdrawal guideline, that gives her a retirement target of around $2 million.

Instead of saying, “Monica makes $125K, so she should invest 20%,” we can ask: What does it take to grow $150,000 into approximately $2 million over the next 30 years? Based on the assumptions used in this example, Monica needs to invest roughly $800 per month. Plot twist: she’s currently investing $1,500.

She could absolutely keep doing that. Maybe she retires earlier. Maybe she front-loads even more now so she can contribute less later.

Or…she could spend some of it. Maybe she takes an incredible vacation with her mom. Gets a massage twice a month. Hires a housekeeper. Finally tries Reiki with her woo-woo friend because apparently we have a $200 experimentation budget now.

Love that for Monica. She isn’t spending more because she gave up on her future. She can spend more because she understands her future.

Stella: $400K invested and dreaming of part-time work

Stella is 38, earns $130,000 and already has $400,000 invested. She also wants roughly $80,000 per year in retirement but her actual dream is to leave her higher-paying career and work part-time at 50, earning around $50,000 until she fully retires around 65.

If Stella stopped investing another dollar today and her existing $400,000 continued growing under the assumptions used in our projection, she could have roughly $900,000 at 50.

If she left that invested until 65, it could grow to roughly $2.5 million. Stella may have already reached what's commonly called Coast FI: the point where your existing investments may be enough to grow toward your retirement target without additional contributions, assuming the projection plays out.

Think about what that opens up. She can keep investing and build an even bigger cushion. Or she could save for another goal, travel more, donate more or potentially reduce her workload sooner. At some point, your money starts doing more of the heavy lifting than you do.

If you never run the numbers, you might blow right past that milestone while still thinking, More. More. More. I should be investing more. Meanwhile your investments are over there like, Girl, we’ve got this.

Ashley: A baby, a house…and a reason to invest less

Ashley is 35. She and her partner earn $200,000 combined and have $300,000 invested for retirement. They’re having a baby and want to buy a house within the next few years. They estimate wanting around $160,000 per year in retirement, giving them a rough $4 million target.

Right now they invest about 20% of their income, or $3,300 per month.But they also have $40,000 saved toward a house and want approximately $150,000 for the down payment, closing costs and moving expenses within three years.

They need another $110,000. Because they already have $300,000 invested at 35, their retirement projection gives them room to temporarily reduce contributions. In this example, they could potentially invest around $750 per month for the next five years, redirect more cash toward the house and baby, and later increase their retirement investing to around $1,550 per month while remaining on track under the assumptions used.

This doesn't mean everyone with $300K invested should slash their 401(k). It means we can model the tradeoffs instead of blindly following a percentage.

Future you isn’t only 65-year-old retired you. Future you is also 38-year-old you buying a house.

42-year-old you taking a year off. 50-year-old you finally working three days a week.

Your money should support all of her.

PART 3: Find Your “Enough” Number

You can earn $150,000, max your 401(k), have hundreds of thousands invested and still feel financially anxious.

Because “more” has no finish line. If your strategy is simply save more, invest more, spend less, there will always be another dollar you technically could have invested.

You can skip the vacation. Keep cleaning your own house. Stay in the job you hate a little longer. And yes, future you would have more money. But having the biggest possible pile of money is not the goal.

The goal is building enough wealth to create the life you actually want.

What to do next

Start by putting your numbers in one place. Add up your retirement accounts, brokerage accounts, savings and debt. Then ask yourself what you’re funding and get more specific than “retirement.”

When would you love to stop working full-time? What kind of house do you want? Do you want kids? Do you want to help pay for college? Is there a career change somewhere in your future? Would you rather retire at 55, or work until 65 but take more time off while your kids are little?

Then attach timelines and numbers to those goals. You don’t need a crystal ball. You’re allowed to estimate and adjust as life changes.

This isn't about being perfect. It's about replacing vague financial anxiety with actual information. Once you know what you're funding, you can work backward to estimate the monthly contribution needed to close the gap between where you are and where you want to go. And then you can decide what to do with everything else.

The goal is confidence, not optimization

Imagine booking the trip without hearing that little voice say, Should I have invested this instead? Imagine reducing your hours, hiring help around the house, buying the house you love or taking a career risk because you’ve actually run the numbers and understand the tradeoffs.

That’s the kind of financial confidence I care about. I want your life to be rich, not just your bank account. If you want to better understand what you already own, start with my free Guide to Understanding Your Investment Portfolio.

In my free Are You On Track? masterclass, I’ll walk you through how to look at what you already have invested, what you want your mone y to make possible, and whether you’re actually on track to get there.Join my masterclass here

And if you want help looking at your actual numbers, goals and decisions, you can book a 90-Minute Money Clarity & Decision Support Session here. We’ll look at your whole financial picture and help you understand what your money can actually make possible.

FAQ

Is investing 20% of my income enough?

It can be a useful benchmark, especially early in your investing journey, but it doesn't tell you whether you're on track for your goals. Your existing investments, timeline and desired lifestyle matter too.

Can I invest too much money?

You can invest more than you need for a particular goal or timeline. That may be intentional—but if investing more is making your current life unnecessarily difficult, it's worth understanding the tradeoff.

How do I know if I’m investing enough for retirement?

Start with your estimated retirement spending, current investments and timeline. From there, estimate the portfolio you’ll need and work backward to determine the monthly contribution that could get you there. Revisit the projection periodically as your life and the market change.

Should I max out my 401(k)?

Not automatically. Maxing your 401(k) can be a fantastic choice, but it’s a tool—not the goal. Consider retirement alongside your cash reserves, home purchase plans, career goals and other priorities.

The Real Answer to “How Much Should I Invest Per Month?”

There isn't one percentage that can answer that for everyone. Your number depends on what you already have, what you're funding, when you need the money and what matters most to you.

Monica needs her money for retirement at 65. Stella wants hers to create career freedom at 50. Ashley needs to balance retirement with a house and a baby much sooner. Their salaries alone can't tell us what to do.

Their lives can. And once you know your number, investing stops feeling like this endless test you might secretly be failing. You know what you're doing. You know why you're doing it. You can adjust when life changes and you can start letting your money do what you worked so hard to build it for:

Give you more freedom, more choices and more life.