A calculator gives you a number. These guides tell you where the number comes from — the formulas, the assumptions, and the judgment calls — so you can trust the result and use it well. Written in plain English, no jargon walls.
Every guide here is paired with a free Figro tool. Read the guide to understand the concept, then run your own numbers in the tool — no signup, nothing uploaded. We wrote these because a result you don't understand is a result you can't check, and money decisions deserve to be checked.
A quick note: these guides are educational, not personalized financial, tax, or medical advice. For decisions with real stakes, confirm the details with a qualified professional.
Two rates that look alike but mean opposite things — which one you pay, which one you earn, and why the gap matters.
Read guide → Real EstatePrincipal, interest, taxes, and insurance — the PITI formula that turns a home price into a real monthly number.
Read guide → Real EstateBeyond "renting is throwing money away" — the real break-even math, hidden costs, and when each choice wins.
Read guide → MoneyA 2026 US tipping guide — restaurants, delivery, rideshare, and more, with the rates people actually expect.
Read guide → HealthWhy waking mid-cycle feels awful — how 90-minute cycles work and how to time your bedtime or alarm.
Read guide → MoneyWhy the rate you get isn't the rate you see — spreads, the mid-market rate, and how to avoid hidden fees.
Read guide → CareerWhat recruiters actually scan for, the format that survives ATS filters, and the lines worth cutting.
Read guide → InsuranceThe 3-to-6-month rule and when to go bigger — how to size a cushion to your real monthly expenses.
Read guide → InsuranceWhy you insure the rebuild cost, not the price you paid — dwelling, liability, and the coverage gaps to watch.
Read guide → CareerThe market-rate research, the number to name, and the script — how to make the ask actually land.
Read guide → Real EstateThe ratio lenders use to size an investment loan — how debt service coverage works and the number to clear.
Read guide → Real EstateARV, the 70% rule, holding costs, and the margin that separates a profitable flip from a loss.
Read guide → DeveloperThe data format behind almost every API — what it is, its syntax rules, and how to read and validate it, with examples.
Read guide → DeveloperRegular expressions in plain English — the syntax that finds and matches text patterns, explained from scratch with real examples.
Read guide → DeveloperWhy binary data gets turned into text — how Base64 works, when to use it, and why it isn't encryption.
Read guide → DeveloperMD5, SHA-256, and what hashing actually does — one-way fingerprints for data, passwords, and integrity checks.
Read guide → DeveloperThe 128-bit IDs that stay unique without a central server — UUID v4 vs v7, and when to use each.
Read guide → Web DesignOffset, blur, spread, and color — every box-shadow value explained, plus how to layer shadows for real depth.
Read guide → SEOTitle, description, Open Graph, and more — the HTML tags that shape how your page looks in search and social.
Read guide → SaaSMRR, ARR, churn, LTV, and CAC — the numbers every founder tracks, what they mean, and how they connect.
Read guide → DesignColor theory without the jargon — complementary, analogous, and how to build a palette that actually looks good.
Read guide → Web DesignLinear vs radial, color stops, and the tricks that separate a clean gradient from a muddy one.
Read guide → ProductivityThe 25-minute focus method — how it works, why it beats marathon sessions, and how to actually stick to it.
Read guide → ProductivityThe science of streaks — why "don't break the chain" works, and how to build a habit that survives a missed day.
Read guide → ProductivityWhat WPM really measures, why accuracy beats raw speed, and the practice that actually moves the number.
Read guide → CareerRestricted stock units explained — how they vest, why they're taxed as income, and the mistake that leads to a surprise bill.
Read guide → InsuranceTwo tax-free health accounts, very different rules — 2026 limits, the HDHP catch, and which one to pick.
Read guide → TaxesThe 15.3% every freelancer owes, the 2026 Social Security wage base, and the deductions that shrink the bill — with a worked example.
Read guide → Real EstateThe two numbers every commercial deal turns on — NOI and cap rate — with the formulas, a worked example, and the DSCR check.
Read guide → InsuranceThe 60–70% income-replacement rule, own-occupation vs any-occupation, and how SSDI fits in — so a lost paycheck doesn't sink you.
Read guide → CareerWeeks-per-year formulas, the 22% supplemental tax bite, and what's actually negotiable when you're handed a package.
Read guide → MoneyTotal cost of ownership, depreciation, and the 2026 Section 179 rules — when leasing actually wins and when it quietly costs more.
Read guide → Home & EnergyPayback period, LCOE, and 25-year savings — plus the 2026 change that ended the 30% federal credit for owned systems.
Read guide → SecurityWhy a long passphrase beats a short jumble of symbols, what "entropy" really measures, and the fastest way to make every account uncrackable.
Read guide → FinanceFederal tax, FICA, and 401(k) — where every dollar between your salary and your take-home pay actually goes, and why your refund isn't free money.
Read guide → FinanceWhy your early loan payments are almost all interest, how the schedule flips over time, and what one extra payment a year really saves you.
Read guide → InsuranceThe DIME method versus the "10x income" rule of thumb, with a worked example — and why term insurance usually beats whole life.
Read guide → Real EstateBuy, Rehab, Rent, Refinance, Repeat — how investors recycle one pile of cash into many rentals, with the math and the traps.
Read guide → CareerWhy your freelance rate is not your old salary divided by 2,080 — and how to price in unpaid time, overhead, and self-employment tax.
Read guide → TaxesThe S-corp election can cut your self-employment tax — but only above a certain profit. Here's the breakeven math and the catch.
Read guide → HealthFrom BMR to TDEE to a daily protein, carb, and fat target — the standard formulas, explained, so your numbers aren't a guess.
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