Browse 28 deep dives: 6 on Compound Interest, 5 on Savings Goals, 6 on Debt & Mortgage, 6 on FIRE, and 5 on Subscriptions. Each one shows the maths with real numbers and links straight to its calculator.
Showing 12 of 28 guides
By Y.W. Fung · Verified
How $1,000 today becomes $1,967 in 10 years at 7%, and why waiting 3 years costs about $400.
TL;DR: Waiting 3 years to invest $1,000 costs ~$400 by year 10.
Read GuideBy Y.W. Fung · Verified
On a $10,000 balance at 5%, daily compounding beats annual by roughly $13 in year one — under 0.13%.
TL;DR: Frequency adds ~$13 a year on $10,000 at 5%.
Read GuideBy Y.W. Fung · Verified
Automating $500 a month for 20 years at 7% builds about $260,000 without a single manual transfer.
TL;DR: $500/mo automated for 20 years ≈ $260,000 at 7%.
Read GuideBy Y.W. Fung · Verified
The two-part formula worked line by line: $5,000 start plus $300 a month for 25 years reaches roughly $270,000 at 7%.
TL;DR: $5,000 + $300/mo for 25 years ≈ $270,000 at 7%.
Read GuideBy Y.W. Fung · Verified
Hitting $1,000,000 needs about $380 a month over 40 years, but roughly $1,700 a month if you only have 25.
TL;DR: $1M needs ~$380/mo over 40 years, ~$1,700/mo over 25.
Read GuideBy Y.W. Fung · Verified
Investing $60,000 at once beats spreading it over 12 months by roughly $2,500 after 10 years at 7%.
TL;DR: Lump sum beats 12-month drip by ~$2,500 over 10 years.
Read GuideBy Y.W. Fung · Verified
On $3,500 of monthly essentials, a 6-month buffer is $21,000 — about 29 months of saving at $600 a month.
TL;DR: $3,500/mo essentials = $21,000 buffer, ~29 months to fund.
Read GuideBy Y.W. Fung · Verified
On a $5,000 monthly take-home, 50/30/20 means $2,500 needs, $1,500 wants and $1,000 saved — $12,000 a year.
TL;DR: $5,000/mo income = $1,000 saved monthly, $12,000 a year.
Read GuideBy Y.W. Fung · Verified
A 0.40% yield gap on a $25,000 cash buffer is about $100 a year — the protection structure matters more.
TL;DR: 0.40% gap on $25,000 is only ~$100 a year.
Read GuideBy Y.W. Fung · Verified
A $30,000 target at $700 a month lands in about 41 months; raising it to $1,000 cuts that to 29.
TL;DR: $30,000 goal: 41 months at $700/mo, 29 at $1,000/mo.
Read GuideBy Y.W. Fung · Verified
On a $400,000 home, a 20% deposit is $80,000 — roughly 8 years at $800 a month, versus 2 years for 5%.
TL;DR: $80,000 deposit ≈ 8 years at $800/mo; 5% takes ~2.
Read GuideBy Y.W. Fung · Verified
Across $25,000 of mixed debt, avalanche typically saves $300–$900 of interest and finishes a month or two sooner.
TL;DR: Avalanche saves ~$300–$900 on $25,000 of debt.
Read GuideThe 4% rule says you can withdraw 4% of your portfolio in the first year of retirement, then adjust that amount for inflation each year. Spending $60,000 a year implies a $1,500,000 portfolio. Our guide on how the 4% rule works walks through where it holds and where it breaks.
Yes, as a side effect of amortization: interest is charged on the outstanding balance, so early payments are mostly interest. On a $300,000 loan at 6.5%, the first five years of payments retire only about $19,000 of principal. Our amortization guide shows the full schedule.
Most households target three to six months of essential spending. At $3,500 a month of essentials, a six-month buffer is $21,000, which takes about 29 months to build at $600 a month. Our emergency fund guide covers sizing, funding and where to hold it.