If you asked ten financial experts what matters most for building
wealth, you’d get ten different answers. Pick the right stocks. Buy
property. Start a business. Find a high-interest account. Negotiate a
better salary.
They’re not wrong, exactly. But they’re all missing the one number
that actually predicts your future — a number so simple most people
never bother to calculate it.
Your savings rate.
What It Is
Your savings rate is the percentage of your income that you keep —
money that doesn’t get spent, and instead goes toward savings,
investments, or debt payoff.
The formula is almost embarrassingly simple:
Savings Rate = (Income − Spending) ÷ Income
If you earn 50,000 a month and spend 45,000, you’re saving 5,000.
That’s a 10% savings rate. If you earn the same 50,000 but spend 35,000,
you’re saving 15,000 — a 30% savings rate.
Notice what’s missing from that formula: how much you earn in
absolute terms. That’s the point.
Why This Number Beats
Income Every Time
Here’s a thought experiment. Two people, same age, same starting
point.
Person A earns a high income. Let’s say they take
home a healthy salary. But their spending rises right alongside it —
bigger rent, nicer car, more dining out. They save 5% of what they
earn.
Person B earns roughly half of what Person A earns.
But they’ve kept their lifestyle modest as their income has grown. They
save 40% of what they earn.
Who ends up wealthier?
Almost always, it’s Person B — and it isn’t close. Because wealth
isn’t built from what you earn. It’s built from what you keep,
and then what that kept money is allowed to do over time (more on that
in Chapter 5). Person A’s higher income is irrelevant if none of it
survives past payday.
This is the part that trips people up: your savings rate is
something you control almost completely, regardless of what you
earn. Your salary might depend on your industry, your
negotiating position, your economy. Your savings rate depends on
decisions you make every single month.
Your
Savings Rate Also Tells You How Long You’ll Work
There’s a second, more startling reason this number matters: it
doesn’t just determine whether you build wealth — it determines
how many years you’ll need to work before your money can
support you.
Roughly speaking (we’ll get into the real mechanics in Chapter
5):
- Save 10% of your income → expect to need something like 40+ years of
saving before your investments could replace your income - Save 25% → that drops to roughly 25 years
- Save 40% → roughly 17 years
- Save 50%+ → under 15 years
This isn’t magic. It’s math. The more you save, the less you need
(because your expenses are lower) and the more you have working
for you at the same time. Both sides of the equation move in your favor
at once.
Calculate Yours Right Now
Don’t skip this. Grab last month’s numbers — your bank statement,
your M-Pesa statement, whatever you use — and work out:
- What you actually took home
- What you actually spent (all of it — rent, food, transport,
subscriptions, everything) - The difference, divided by what you took home
That percentage is your starting point. Don’t judge it yet. Most
people, doing this for the first time, are surprised — sometimes
pleasantly, often not.
If your number is negative (you spent more than you
earned), Chapter 4 is your priority — you’re dealing with debt
compounding against you, and that needs attention before anything
else.
If your number is 0–10%, you’re in the majority.
This book is going to move that number.
If your number is already 20%+, you have a real head
start. Chapters 5 through 8 will show you how to make that money work
harder.
The Companion Tracker
Alongside this book, the Compounded tracker (included with your
purchase) does this calculation for you automatically each month, and
shows your savings rate trending over time. A single number, updating in
real time, is far more motivating than a spreadsheet buried three tabs
deep — that’s the whole design idea behind it.
For now, though: write your number down somewhere. You’re going to
want to compare it to where you are in a few months.