CALCMONEY // GUIDES // PAGE 10 OF 25
Blog.
Numbers-first guides on mortgages, taxes, retirement, and net worth. No opinions, no fluff.
How to Calculate Military Retirement Pay Under BRS and the Legacy System
Most service members estimate their retirement pay without running the actual formula. That gap between estimate and reality can cost six figures over a 20-year retirement. The math is not complicated, but it demands precision.
Mega Backdoor Roth: The $43,500 Conversion Most High Earners Miss
Most high earners max their 401(k) at $23,500 and stop there. That leaves up to $43,500 of after-tax contribution room untouched every year. The mega backdoor Roth converts that money into tax-free growth, permanently.
How to Calculate the Business Mileage Deduction in 2026 (And Stop Leaving Money Behind)
Most self-employed taxpayers undercount their deductible miles by 15% to 30% because they track reactively, not systematically. The IRS standard mileage rate for 2026 is 70 cents per mile, and every unlogged trip is a direct cash loss. This post shows you exactly how to calculate what you're owed.
How to Calculate Monthly Recurring Revenue for a Subscription Business
Most subscription founders report MRR incorrectly by mixing one-time fees, annual prepayments, and trial conversions into a single number. That error distorts churn rates, misrepresents growth velocity, and produces forecasts that fail within 90 days. Here is the precise method.
The LTV to CAC Ratio: What a Healthy SaaS Business Actually Looks Like
Most SaaS founders track LTV and CAC as separate metrics and miss the only number that actually predicts survival. A 3:1 LTV to CAC ratio is the floor, not the goal. Get the exact calculation and see where your unit economics stand.
Lump Sum vs. DCA: How to Calculate Which Strategy Actually Wins
Most investors default to dollar-cost averaging because it feels safer. The data says that costs them money in roughly 2 out of every 3 market environments. Here is how to run the numbers before you commit.
How to Calculate Mortgage Payoff with Extra Payments (And What It Actually Saves You)
Most homeowners never calculate the true cost of their payoff timeline. A single extra monthly payment per year on a $400,000 mortgage eliminates 4.5 years of interest. The math is simple. The savings are not small.
How to Calculate a Mortgage Payment Using the Formula
Most borrowers accept the monthly payment their lender quotes without verifying the math. A single input error or rate misquote can cost you thousands over the life of the loan. The formula is not complicated, and knowing it puts you in a different position at the closing table.
How to Calculate a Mortgage on an Investment Property (And Why Most Investors Get It Wrong)
Most investors calculate their investment property mortgage the same way they calculated their primary home loan. That mistake can cost them $40,000 or more over the life of the loan. The variables are different, the rates are higher, and the qualification math runs on different logic entirely.
How to Calculate Your Mortgage Interest Deduction Value
Most homeowners claim the mortgage interest deduction without calculating whether it actually saves them money. The standard deduction threshold means millions of filers get zero benefit while assuming otherwise. Here is exactly how to run the numbers before you file.
A 1% Mortgage Rate Change Costs More Than You Think
Most buyers anchor on the interest rate. They should anchor on the dollar difference between rates. On a $400,000 loan, a 1% rate gap costs $268 more per month and $96,692 over 30 years. That math deserves more than a shrug.
How to Calculate Your Monthly Mortgage Payment (And Why Most Buyers Get It Wrong)
Most buyers focus on the purchase price. The monthly payment is what actually determines whether you can close without financial stress. One input error in the amortization formula costs you thousands in miscalculated budget capacity.
How to Calculate Your Mortgage Pre-Approval Amount Before the Bank Does
Most buyers find out their pre-approval amount at the lender's office, then build a home search around that number. That is backwards. Calculate your own ceiling first, and you walk in knowing exactly what the bank will say before they say it.
How to Calculate Your Mortgage Payoff Date With Extra Payments
Most homeowners guess their payoff date based on their loan term. That guess costs them tens of thousands of dollars. Extra payments compound against your principal in ways the standard amortization schedule never shows you.
The True Cost of Only Making Minimum Payments (And How to Calculate It)
Minimum payments are designed to keep you in debt, not get you out of it. A $5,000 balance at 22% APR can cost you nearly $5,000 in interest before it's gone. The math is straightforward once you run it.
LLC vs S Corp: Calculate Which Saves You More on Taxes (Real Numbers)
Most entrepreneurs pick their business structure based on what their friend told them. This costs them thousands every year. Here's how to calculate which structure actually saves you money.
Marginal vs. Effective Tax Rate: Why Most People Overpay By Misunderstanding Their Bracket
Getting a raise that pushes you into the next tax bracket does not mean all your income gets taxed at the higher rate. Here is how marginal tax rates actually work and why the confusion costs people money.
How to Calculate Loan Costs: Compare Offers Like a Pro
Lenders rely on marketing illusions to confuse consumers. Understanding total lifetime costs versus appealing monthly payments is your primary defense metric.
How to Calculate Mortgage Payments: A Complete Guide to PITI
Buying a home is the largest financial transaction of your lifetime. Yet, most buyers don't understand how their monthly payment is actually calculated. Mathematics protects you from disaster.
New Construction vs. Existing Home: How to Calculate the True Total Cost
Most buyers compare list prices and stop there. That calculation misses tens of thousands of dollars in costs that don't appear on the purchase contract. Run the full number before you sign anything.
Mortgage Origination Fees: How to Calculate the True Cost Before You Sign
Most borrowers see an origination fee as a line item and move on. That single number can quietly add thousands to your loan's real cost. Calculate it against your break-even timeline before you close.
How to Calculate How Much You Save by Moving to a No Income Tax State
Most people guess their tax savings from relocating. That guess is almost always wrong, because it ignores effective rates, local taxes, and cost-of-living offsets. Here is the exact calculation that tells you the real number.
How to Calculate Owner's Pay From a Small Business Correctly
Most small business owners set their own pay by gut feel, then wonder why they owe a surprise tax bill every April. The correct method starts with your business structure, not your bank balance. Get the math wrong and you'll either underpay yourself or trigger an IRS audit for paying an 'unreasonable' salary.
How to Calculate Multi-Family Real Estate Investment Returns (The Right Way)
Most investors quote cap rate and stop there. That single number ignores financing costs, vacancy drag, and capital expenditures that routinely cut real returns in half. Here is the complete framework for calculating what a multi-family property actually pays you.
Municipal Bond Tax-Equivalent Yield: The Formula High-Earners Must Run Before Buying
A 4% municipal bond yield is not automatically better than a 5% corporate bond yield. Without running the tax-equivalent yield formula, high-income investors routinely pick the wrong instrument and leave thousands of dollars on the table each year.
Part-Time Job vs. Unpaid Internship: How to Calculate the Real Financial Value of Each
Most students compare a part-time job and an unpaid internship by gut feeling, not math. The financial gap between the two options can exceed $14,000 in a single academic year. This post shows you how to run the numbers correctly.
How to Calculate NFT Capital Gains Tax Properly
Most NFT sellers report the wrong cost basis, misclassify their holding period, or ignore royalty income entirely. The IRS treats NFTs as collectibles in many cases, which means a 28% federal rate instead of 20%. Here is how to calculate what you actually owe.
How to Calculate Net Investment Income Tax at 3.8%: The Number Most High Earners Miss
The 3.8% Net Investment Income Tax is not optional, not obscure, and not small. High earners routinely underprepare for it because they treat it as an afterthought to ordinary income tax. That mistake can cost tens of thousands of dollars in a single tax year.
How to Calculate Payback Period on Any Business Investment
Most investors eyeball payback period and miss the real breakeven by months, sometimes years. The formula is straightforward, but the inputs most people use are wrong. Get the math right and you stop funding slow-return projects with capital that belongs elsewhere.
How to Calculate PEG Ratio and Find Undervalued Growth Stocks
Most investors screen stocks by P/E ratio alone and miss the growth dimension entirely. A stock trading at 35x earnings can be cheaper than one trading at 18x. The PEG ratio is the calculation that reveals which is which.
The Real Cost of Keeping Cash in a Savings Account (And How to Calculate It)
Most savings accounts pay between 0.01% and 0.50% APY while inflation runs at 3% or higher. Every month you leave cash parked in a low-yield account, you are losing purchasing power in measurable dollar terms. Here is how to calculate exactly what that inertia is costing you.
The True APR of a Payday Loan Is 400%. Here's the Math.
A $15 fee on a $100 payday loan sounds manageable. Annualized, that fee becomes a 391% APR. Most borrowers never run that calculation before signing.
How to Calculate Peer-to-Peer Lending Net Return After Defaults
Most P2P investors report their gross yield and call it a return. That number is fiction. Once you account for defaults, platform fees, and the drag of uninvested cash, your actual net return can fall 3 to 5 percentage points below what the dashboard shows you.
Parent PLUS Loans Cost Far More Than the Sticker Price. Here's the Real Math.
Most parents sign Parent PLUS loan paperwork focused on the annual disbursement amount. That number is irrelevant. The number that matters is total repayment cost, and for a $50,000 loan at the current 9.08% rate, it can exceed $76,000 on the standard plan. Run the correct calculation before the first payment is due.
The True Loaded Cost Per Employee Is 1.25x to 1.4x Their Salary. Most Owners Get This Wrong.
Most business owners calculate payroll cost as the salary they agreed to pay. That number is wrong by 25% to 40% before the first check clears. The true loaded cost includes taxes, benefits, and overhead that never appear on the offer letter.
How to Calculate Options Break-Even Price Before You Buy
Most options buyers never calculate break-even before entering a trade. They focus on the strike price and ignore the premium, which means they're losing money on expiration day without realizing it. The math takes 30 seconds and changes every decision you make.
How to Calculate Net Operating Income on Investment Property
Most investors calculate NOI wrong because they confuse gross rent with effective income and ignore vacancy entirely. A single miscalculation on a $500,000 property can shift your cap rate by a full percentage point. Here is the exact formula professional underwriters use.
How to Calculate Net Present Value (NPV) for Any Investment
Most people lose money on investments because they ignore the time value of money. A $10,000 profit in 5 years isn't worth $10,000 today. Here's how to calculate what it's actually worth.
How to Calculate Net Revenue Retention for a Subscription Business
Most subscription founders track MRR and call it a day. Net Revenue Retention tells you whether your existing customers are growing your business or slowly draining it. If you're not calculating NRR monthly, you're flying blind on the metric investors weight most.
How to Calculate Net Unrealized Appreciation: The NUA Tax Strategy That Saves Six Figures
Most 401(k) holders roll their employer stock into an IRA and pay ordinary income tax on every dollar. The NUA strategy taxes the growth at long-term capital gains rates instead. For concentrated employer stock positions, the difference can exceed $100,000 in lifetime tax savings.