Blog — Guides, Comparisons & Real Numbers
Practical guides that pair with our calculators: mortgage math, freelance pricing, hosting costs, ad profitability and more — every claim worked through with real numbers you can verify in the tools.
Loans & Mortgages
15-Year vs 30-Year Mortgage: The Real Numbers
Choosing between a 15-year and 30-year mortgage is a tradeoff between monthly breathing room and lifetime interest.
How One Extra Payment a Year Cuts Years Off Your Loan
Extra principal payments are the quiet superpower of amortized loans.
APR vs Interest Rate: Compare the Right Number
Two loans can advertise the same interest rate and cost very different amounts.
Investing & Returns
The Rule of 72: Why Starting Early Beats Investing More
The Rule of 72 is the fastest mental math in finance: divide 72 by your annual return and you get the number of years for money to double.
CAGR vs Average Return: Beware the Volatility Trap
Averaging yearly returns is one of the most common ways investors fool themselves.
How to Evaluate an Investment with ROI (and Its Blind Spots)
ROI answers a deceptively simple question: for every dollar in, how many came out? Its simplicity is its power and its danger — the same simplicity hides time, risk and cost if you let it.
Salary & Tax
Salary vs Hourly: Which Actually Pays More?
A $65,000 salary and a $32/hour contract look nearly identical until you count the hours actually worked, the benefits actually received, and the taxes actually paid.
Why Your Paycheck Is Smaller Than Salary ÷ 12
A $75,000 salary does not produce a $6,250 monthly deposit.
Freelance Pricing: Work Backwards From the Income You Want
Most freelancers price by guessing what sounds reasonable, then discover their effective hourly rate after taxes is barely above their old salary.
Business & Hosting Costs
9 Practical Ways to Lower Your Hosting Bill
Hosting bills rarely explode — they creep.
The Hidden Cost of SaaS Sprawl — and a 30-Minute Audit
No one decides to spend $2,000 a month on software.
What an Employee Really Costs: The 1.4× Rule
The most common budgeting error in small companies is treating salary as cost.
Break-Even Analysis: Worked Examples for Small Businesses
Break-even analysis is the most decision-dense math in small business: three inputs that tell you whether a price, a product or a storefront is viable.
Margin vs Markup: The Pricing Mistake That Kills Stores
Ask for a product with 'a 50% margin' and you may receive one with a 33% margin.
Marketing & Growth
Your ROAS Looks Good — but You're Losing Money
The most expensive number in paid marketing is a flattering ROAS.
CPM vs CPC vs CPA: Which Metric Matters When
Every ad price is one of three currencies: money per thousand views (CPM), money per click (CPC), or money per outcome (CPA).
LTV:CAC Explained: The 3:1 Rule and the Cash Behind It
Two numbers decide whether a growth engine is real: what a customer contributes over their lifetime (LTV) and what it costs to acquire them (CAC).