How much of what your assets earn you put back to work. It's the throttle on compounding — and not everyone can reach it.
When an asset earns — a dividend, a profit, some interest — you face a choice every time: take that money out and spend it, or feed it back in to buy more and grow. Your reinvestment rate is that choice written as a percentage: the share of returns you put back to work instead of taking out.
It matters enormously because it's the throttle on compounding. Compounding only happens to the part you leave in. Take all the returns out, and your base never grows. Put them back, and each year's earnings start earning too.
Take the same $100,000 asset earning 8% a year for 20 years. The only thing that changes is how much of the return you reinvest versus spend:
Same asset, same return, same two decades — and the base ends up more than four times larger purely from the choice to reinvest. At 0%, you enjoyed the income along the way but the base never moved. The reinvestment rate, quietly, is one of the most powerful numbers in your financial life.
The same choice shows up everywhere money is earned:
A dollar taken out is enjoyed once. A dollar reinvested keeps earning for as long as you let it.
You don't need a high reinvestment rate to start — you need a consistent one that grows as your income does.
There's a hard limit that the "just reinvest everything" advice ignores: you can only reinvest what you don't need to live on. A high reinvestment rate is partly a privilege of already having enough — the family living on its income reinvests little, and that's not a failure of discipline, it's arithmetic. Don't feel like you're doing it wrong for spending what you genuinely need.
Two more truths. Reinvesting means resisting the pull to take the money and enjoy it now — and then waiting through compounding's slow middle before it shows. And reinvesting everything back into the same thing quietly concentrates your risk; even a high reinvestment rate should still spread out. The honest target isn't 100%. It's the highest rate you can hold without starving the present.
Reinvestment rate is a quiet engine of concentration, because the ability to reinvest scales with how much you already have. A family that needs its income to live reinvests little; a fortune that doesn't need its income can put nearly all of it back to work, compounding faster and faster. The gap widens not only because the wealthy earn more, but because they can afford to keep more of it working. The same holds for firms: those that can retain and reinvest earnings outgrow those forced to pay them out.
So the structural question is the real one: how do we make reinvestment possible for ordinary people — incomes high enough, and assets accessible enough, that a working family can also afford to put returns back to work, instead of spending every dollar just to get through the month?