5 investment rules everybody must know: You don’t need to be Warren Buffett to understand these simple money basics

Simple money rules can make financial planning easier to understand. They offer quick ways to organise spending, estimate growth and prepare for future expenses. However, these shortcuts cannot replace a plan suited to your circumstances.

Some guide investing, while others strengthen the finances that support it. Here are 5 popular investment rules, with examples explaining their uses and limitations for Indian households. And, these are pretty fundamental rules. You don’t need to be an expert like Warren Buffett to understand these basic money rules.

Rule of 100

The Rule of 100 offers a basic shortcut for deciding your equity allocation. Subtract your age from 100 to estimate the percentage held in shares. At age 35, the formula suggests 65% in equity investments. The remaining 35% would generally go towards bonds or other defensive assets.

However, your age cannot explain your complete financial situation. Two people aged 35 may have different debts, goals and tolerance for losses. Money you need soon may require protection, regardless of how young you are. Consider your income stability and investment deadlines before choosing an allocation. Use this formula to start thinking rather than treating the answer as final.

Rule of 72

The Rule of 72 estimates how long an investment might take to double. Divide 72 by the annual percentage return to approximate the number of years. At a steady 8% annual return, the estimate is 9 years. An investment of ₹1 lakh would then become roughly ₹2 lakh.

This calculation assumes compounded growth, with earnings remaining invested throughout the period. It does not account for taxes, charges or inflation. Market investments also deliver changing returns. So actual doubling times can differ considerably. Use this shortcut to understand the relationship between growth rates and time. A projected return remains an assumption, never a promised outcome.

50/30/20 rule

The 50/30/20 rule gives your monthly income a simple structure. Allocate 50% of your salary after tax towards needs, including rent, groceries and bills. Keep up to 30% for wants, such as outings and entertainment. Direct the remaining 20% towards savings and debt repayment.

For a ₹50,000 monthly income, these amounts are ₹25,000, ₹15,000, and ₹10,000, respectively. The benefit lies in making room for future priorities before optional spending expands. However, expensive housing or family responsibilities may require different proportions. Treat these percentages as a starting point that you can adjust. Review your spending regularly to find a balance your household can maintain over time.

6 Months rule

The ‘6 Months’ rule suggests keeping enough money for six months of essential expenses. This reserve can help during unemployment, urgent repairs or unexpected family needs. If monthly necessities cost ₹30,000, the suggested emergency fund would be ₹1.8 lakh. Include rent, food, utilities, essential instalments and other unavoidable payments.

Build this amount gradually if setting it aside immediately feels difficult. Keep the money accessible and prioritise safety over the pursuit of higher returns. An emergency should not force you to sell investments during a market fall. Six months is a guideline, and irregular earners may need more. Review the target whenever your household expenses or responsibilities increase.

4% rule

The 4% rule is a starting framework for planning retirement withdrawals. It suggests withdrawing 4% of your initial retirement portfolio during the first year. With ₹1 crore invested, that means an initial withdrawal of ₹4 lakh. Later withdrawals adjust that original amount for inflation, rather than recalculating 4% annually.

The approach emerged from historical American investment research covering roughly 30 retirement years. It does not guarantee that savings will last, especially under different Indian conditions. Taxes, investment costs, inflation and retirement length can change the outcome. Healthcare expenses and poor early returns also deserve attention. Review withdrawals regularly instead of following this percentage without adjustments.