Doubling Time Calculator –
Rule of 72 – How Fast Will Money Double?

Rule of 72 is a quick mental math shortcut: Years to double money = 72 ÷ Annual Return Rate. Examples: 6% → 12 years | 8% → 9 years | 10% → 7.2 years | 12% → 6 years | 15% → 4.8 years. The actual formula is: Years = ln(2) / ln(1+r). Rule of 72 gives a very close approximation.

At 12% p.a.: Money doubles every 6 years. In 30 years, money doubles 5 times: ₹1L → ₹2L → ₹4L → ₹8L → ₹16L → ₹32L. But in SIP, you're adding money every month too, so actual wealth creation is even more dramatic than simple doubling calculations.