SIP and lumpsum are not competing products. They are two ways of deploying money. The better choice depends on when you receive cash, how much market risk you can tolerate, and whether you can stay invested during volatility.
When SIPs work well
SIPs match monthly income. They build discipline, reduce the pressure to time the market, and make market falls easier to handle because new instalments buy at lower prices.
When lumpsum works well
If you already have idle cash and your goal is many years away, investing sooner usually gives compounding more time. The challenge is behavioural: a sharp fall soon after investing can make people exit at the wrong time.
A practical middle path
For large one-time money, many investors use a staggered transfer over three to twelve months. This is not mathematically perfect, but it can make the decision easier to stick with.
Match the method to the goal
Use SIPs for salary-led goals such as retirement and education. Consider lumpsum for bonuses, asset sales, or matured deposits, provided your asset allocation still remains balanced.