Ask ten people for a stock market “strategy” and nine of them will give you a stock. A name. A tip. Something to buy.

That’s not a strategy. That’s a guess wearing a strategy’s clothes.

A real strategy doesn’t tell you what to buy.

It tells you how to decide — how much to invest, how to split it, how much risk to carry at your age, and how to eventually draw it back out.

And the best ones don’t need a finance degree to use. They’re just rules.

Simple, number-based, repeatable rules that remove the guesswork from the moments you’re most likely to guess wrong.

This article walks through five core rules that cover the full journey, plus two bonus ones worth knowing — what each rule actually says, where it holds up, where it doesn’t, and how to use them together rather than in isolation.

Table of Contents:

• Why a Rule Beats a Tip
• Rule 1: The 50-30-20 Rule
• Rule 2: The 100-Minus-Age Rule
• Rule 3: The Same-Date SIP Rule
• Rule 4: The 15x15x15 Rule
• Rule 5: The 4% Withdrawal Rule
• Using All Five Rules Together
• Two More Rules Worth Knowing
• Where Rules Stop Being Enough
• Frequently Asked Questions

Why a Rule Beats a Tip

A stock tip is a single decision, made once, that you hope works out.

A rule is a decision-making process you can reuse for the next forty years.

That difference matters more than it sounds like it should.

Markets don’t reward the one clever call nearly as often as they reward the boring, repeatable process — because a process still works on your worst day, and a tip only ever works if you got lucky.

There’s a sobering pattern that shows up again and again in trading circles: a large majority of people who jump into the market without any rules at all end up losing a large share of their capital within their first few months.

Not because they’re careless people — because guessing has no memory. It doesn’t get better with practice the way a repeatable process does.

The five rules below aren’t laws of physics. They’re heuristics — rough, reasonable starting points built to be simple enough to actually follow under pressure.

Think of them less as commandments and more as a set of guardrails: they won’t optimise your last percentage point of return, but they will stop you from doing something genuinely damaging in a moment of panic or greed.

Rule 1: The 50-30-20 Rule — Deciding How Much You Can Even Invest

Before any stock market strategy matters, one question needs answering: how much money is actually free to invest in the first place?

The 50-30-20 rule answers it with a simple three-way split of your monthly take-home income:

• 50% toward needs — rent or EMI, groceries, utilities, insurance premiums, anything non-negotiable
• 30% toward wants — eating out, travel, subscriptions, the things that make life enjoyable but aren’t essential
• 20% toward savings and investing — SIPs, PPF, an emergency fund, anything building your future

On a take-home income of ₹80,000 a month, that works out to roughly ₹40,000 for needs, ₹24,000 for wants, and ₹16,000 that goes straight into building wealth — every single month, before it has a chance to quietly disappear into things you won’t remember buying.

The honest caveat: in expensive Indian cities, “needs” can easily swallow 60-70% of income for younger earners, especially with rent or a large home loan EMI in the mix.

When that happens, the ratio isn’t a failure — it’s a diagnostic.

It tells you exactly where the pressure is coming from, which is the first useful step toward a plan that actually reflects your real numbers instead of a textbook one.

Rule 2: The 100-Minus-Age Rule — Deciding How Much Should Be in Equity

Once you know how much you’re investing, the next decision is where it goes — specifically, how much into equity (which grows faster but swings harder) versus debt (which grows slower but sits still).

The 100-minus-age rule gives you a starting point: subtract your age from 100, and that’s roughly the percentage of your portfolio that could sit in equity.

Age	Suggested Equity	Suggested Debt
25	75%	25%
30	70%	30%
35	65%	35%
40	60%	40%
45	55%	45%
50	50%	50%
55	45%	55%
60	40%	60%

The logic is straightforward: younger investors have more years ahead of them to ride out a bad market cycle, so they can afford more equity.

As retirement gets closer, the portfolio needs to depend less on the market being kind in any specific year, so the mix shifts toward stability.

Worth knowing: some newer variants use 110 or even 120 minus age, on the logic that people are living — and investing — longer than they used to. There’s no single “correct” number here.

What actually matters more than the exact formula is your personal risk appetite, your dependents, and whether you have other assets (property, a family business, a pension) that already give you some stability outside the market.

Use 100-minus-age as a sensible starting conversation, not a fixed destination.

Rule 3: The Same-Date SIP Rule — Deciding How You Actually Enter the Market

Knowing how much to invest and how to split it still leaves one question unanswered: when, each month, do you actually put the money in?

The rule here is almost stubbornly simple: invest a fixed amount on the same date every month, automatically, regardless of whether the Nifty 50 or Sensex is up, down, or flat that day.

This is what a Systematic Investment Plan is built to enforce.

Not because the date is magic — the 1st, the 7th, the 28th all work equally well — but because removing the choice of “today or not” is the entire point.

The moment you let yourself pick and choose which months feel safe enough to invest in, you’ve quietly reintroduced the exact guesswork this whole strategy was built to avoid.

Over enough months, this evens out the highs and lows of the market automatically — you end up buying more units when prices are low and fewer when prices are high, without ever having to correctly predict which is which.

Rule 4: The 15x15x15 Rule — Turning a Monthly Habit into a Real Number

The first three rules tell you how much to invest, how to split it, and when to put it in. This one puts a number on what that habit can actually turn into.

The rule is this: invest ₹15,000 a month, through a SIP, for 15 years, in an equity fund that averages 15% annual returns — and you land in the neighbourhood of ₹1 crore.

It’s a memorable way to grasp the power of compounding, and that’s exactly what it’s meant for.

It’s a teaching tool, not a guarantee.

Real equity returns bounce around a lot more than a flat 15% every year, and no fund can promise that number in advance — markets don’t work on promises.

What the rule gets right, and what’s worth taking from it regardless of the exact numbers, is the shape of the idea: a fixed monthly amount, left alone for a long stretch of time, in equity, tends to build real wealth — far more from the years of staying invested than from any single year of spectacular returns.

Mutual fund returns are market-linked and subject to market risk. The 15% figure above is an assumed illustrative rate, not a guaranteed or promised return, and actual outcomes will depend on the fund chosen and the period invested.

Rule 5: The 4% Withdrawal Rule — Deciding How Much You Can Safely Spend Later

The first four rules are about building the corpus. This one is about the part almost nobody plans for early enough: spending it, without running out.

The rule says you can withdraw about 4% of your retirement corpus in the first year, and continue withdrawing roughly that same amount each year after, without a high risk of exhausting the corpus over a long retirement — provided the remaining balance stays invested and continues to grow.

Here’s what that looks like on a ₹1 crore corpus, withdrawing a fixed ₹33,333 a month (4% of the corpus annually), with the remaining balance assumed to grow at 9% a year:

Year	Approx. Corpus Remaining
1	₹1,05,18,023
5	₹1,31,23,816
10	₹1,80,14,716
15	₹2,56,72,306
20	₹3,76,61,648
25	₹5,64,33,134
30	₹8,58,23,293

This is an illustrative example based on an assumed 9% annual return with a fixed monthly withdrawal — it does not account for inflation adjustments to the withdrawal amount, taxes, expense ratios, or the risk of a few bad years occurring early in retirement, all of which can meaningfully change the real-world outcome. Mutual fund investments are subject to market risk and past performance is not indicative of future returns.

Notice the corpus doesn’t just survive here — it grows, because the assumed return sits comfortably above the withdrawal rate.

That’s the best-case shape of the rule. The real risk isn’t the average return over 30 years; it’s a market downturn landing in the first few years of retirement, when withdrawals are eating into a corpus that hasn’t had time to recover.

This is exactly the kind of scenario a proper retirement withdrawal plan is built to stress-test — a flat 4% is a starting assumption, not a number to set and forget for three decades.

Using All Five Rules Together

Individually, each of these rules answers one question. Put together, in order, they form something closer to an actual strategy:

• 50-30-20 tells you how much you can invest each month
• 100-minus-age tells you how to split that between equity and debt
• The same-date SIP rule tells you how to actually put the money in, month after month
• 15x15x15 gives you a feel for what disciplined investing over time can realistically build
• The 4% rule tells you how to draw it back out once you get there

That’s the entire arc of a financial life, reduced to five numbers you can actually remember. None of them require you to predict which stock goes up next month — which, not coincidentally, is the one thing almost nobody can reliably do.

Two More Rules Worth Knowing

The five rules above cover the full journey — investing, allocating, entering, growing, withdrawing.

These next two aren’t part of that core journey, but they’re useful enough, and asked about often enough, that they’re worth having in your back pocket.

The Rule of 72 — how fast money doubles. Divide 72 by your expected annual rate of return, and the answer is roughly how many years it takes for your money to double. At 12% a year, that’s 72 ÷ 12 = 6 years. At 8%, it’s 9 years. It’s a quick mental shortcut, not a substitute for an actual projection, but it’s a fast way to sanity-check whether a return figure someone’s quoting you is realistic.

The 3-5-7 rule — for anyone who also holds individual stocks. This one isn’t about SIPs or mutual funds — it’s a risk-control rule for direct equity. Risk no more than 3% of your trading capital on any single stock, keep total risk across all your open positions under 5%, and only take a position if the potential gain is at least 7% larger than what you stand to lose if it goes wrong. It won’t tell you which stock to buy, but it will stop one bad pick from doing serious damage to the rest of your portfolio.

Where Rules Stop Being Enough

Here’s the honest limit of every rule in this article: they’re built for the average person in an average situation, and you are neither average nor in one single, unchanging situation.

A rule doesn’t know that you’re supporting ageing parents, or that your income is lumpy because you run a business, or that you’re 45 but have a very high risk appetite and no dependents.

It can’t tell the difference between a market fall that’s noise and one that should genuinely change your plan.

That’s the gap between a rule and a plan — a rule gives you a reasonable default; a plan adjusts that default to your actual life.

That’s really the entire case for sitting down with a financial planner at least once — not to abandon these rules, but to find out which parts of them apply to you as written, and which parts need to be quietly rewritten for your situation before you rely on them for the next twenty years.

We offer an Initial Guidance Call (No Cost) for exactly that reason — a simple, no-obligation conversation to see how these rules map onto your actual numbers, not just the textbook version.

Frequently Asked Questions

Q1. What is the best rule-based strategy for Indian stock market investors?

There isn’t a single “best” one — the 50-30-20, 100-minus-age, same-date SIP, 15x15x15, and 4% withdrawal rules each answer a different question (how much to invest, how to allocate it, when to enter, what it can grow into, and how to draw it down). Used together, they cover most of an investor’s journey.

Q2. Is the 100-minus-age rule still accurate today?

It’s a reasonable starting point, not a fixed law. Some planners now use 110 or 120 minus age given longer life expectancies, but the right number for you depends more on your personal risk appetite and other assets than on any single formula.

Q3. Does the 15x15x15 rule guarantee ₹1 crore in 15 years?

No. It’s an illustrative teaching example assuming a flat 15% annual return, which real equity markets don’t deliver in a straight line. It’s useful for understanding the power of compounding, not as a promised outcome.

Q4. Is the 4% withdrawal rule safe to use for retirement in India?

It’s a useful starting assumption, but it needs adjusting for India-specific factors like higher inflation and the sequence of returns risk in the first few retirement years. Treat it as a first estimate to refine with a proper withdrawal plan, not a fixed number to follow blindly for 30 years.

Q5. Can I follow these rules without a financial advisor?

You can start with them on your own — they’re designed to be simple enough for that. Where an advisor tends to add real value is in adjusting the generic rule to your specific income pattern, dependents, and goals, especially around the equity-debt split and the retirement withdrawal plan.

Q6. Which of these rules matters most for someone just starting to invest?

The 50-30-20 rule, because it’s the one that determines whether there’s any money to invest at all. Get the monthly investing habit going first — the allocation and entry rules matter more once that’s in place.

Q7. What is the 3-5-7 rule in the stock market?

It’s a risk-control rule for individual stock positions, separate from the SIP and allocation rules above: risk no more than 3% of your capital on one stock, keep total risk across all open positions under 5%, and only take a trade where the potential gain is at least 7% bigger than the potential loss.

Q8. What’s the smartest way to invest in stocks?

The smartest approach usually isn’t a clever one — it’s a repeatable one. Deciding your monthly amount, your allocation, and your entry method in advance, and then following that decision consistently, tends to outperform trying to time individual entries and exits.

Q9. Should I just invest in whatever stocks famous investors like Rakesh Jhunjhunwala are buying?

Copying a single position ignores everything that made it right for that investor — their time horizon, their risk capacity, their reasons for buying, and their exit plan, none of which you can see from the outside. It’s the opposite of a rules-based approach: a rule works because you understand and control it, not because someone else does.