Are LopperX financial calculators completely free to use?

Yes. Every calculator on LopperX is 100% free with no registration, subscription fees, email gates, or paywalls.

Does LopperX store my salary or debt numbers?

No. All calculations are executed purely in client-side JavaScript within your browser memory. No financial inputs are transmitted to or logged on remote servers.

What are the 2026 IRS 401(k) and IRA contribution limits?

For the 2026 tax year, the IRS elective deferral limit for 401(k) and 403(b) plans is $23,500 ($31,000 for workers aged 50+ with the $7,500 catch-up). The IRA limit is $7,000 ($8,000 with the $1,000 catch-up for individuals aged 50+).

How is a monthly mortgage payment calculated?

A standard US mortgage payment consists of Principal & Interest computed via M = P[r(1+r)^n]/[(1+r)^n - 1], combined with monthly escrow for property taxes, homeowners insurance, and private mortgage insurance (PMI) if loan-to-value exceeds 80%.

Frequently Asked Questions (FAQ) – Financial Math Hub

General Platform & Privacy

Is LopperX truly 100% free with no hidden fees?

Yes. Every single one of our 15 financial calculators is completely free. There are no paid tiers, subscription paywalls, or requirement to input your email address.

Is my personal financial data saved or shared with third parties?

Never. LopperX runs on a client-side architecture. All calculations occur locally in your web browser's JavaScript engine. No numbers you enter into our forms are transmitted, logged, or stored on any server.

How frequently are statutory limits updated?

Our central data library is updated annually within 48 hours of official releases from the IRS, CFPB, and FHFA. Current parameters reflect 2026 inflation-adjusted limits.

Home & Mortgage Calculators

What does PITI mean in a mortgage payment?

PITI stands for Principal, Interest, Taxes, and Insurance. It represents the complete monthly cash outflow of homeownership, often bundled into a single monthly payment by your mortgage servicer through an escrow account. Learn more on our Mortgage Calculator.

When does Private Mortgage Insurance (PMI) automatically cancel?

Under the federal Homeowners Protection Act of 1998, conventional lenders must automatically terminate PMI when your principal balance reaches 78% of the original purchase price. Borrowers can also request manual cancellation once reaching 80% LTV.

What is the 28/36% Debt-to-Income rule?

The 28/36 rule is the classic benchmark used by mortgage underwriters: housing costs (PITI + HOA) should not exceed 28% of your gross monthly income (front-end DTI), and total monthly debt payments should not exceed 36% (back-end DTI). Test your profile on our DTI Calculator and Home Affordability Calculator.

Retirement Planning & Taxes

What is the difference between a Traditional 401(k) and a Roth 401(k)?

Traditional 401(k) contributions are made pre-tax, reducing your taxable income today, but withdrawals in retirement are taxed as ordinary income. Roth 401(k) contributions are made with after-tax dollars; growth and qualified distributions in retirement are 100% tax-free. Model both on our 401(k) Calculator.

What is the 4% Rule and Trinity Study?

The 4% Rule states that a retiree with a balanced portfolio of 50-75% equities and 25-50% bonds can withdraw 4% of their initial portfolio value in year one, adjusting each year for inflation, with a 95%+ probability that the portfolio will survive at least 30 years. Calculate your number on our 4% Rule Calculator.

What is the 2026 standard deduction?

For the 2026 tax year, the projected IRS standard deductions are: $15,000 for Single filers, $30,000 for Married Filing Jointly, and $22,500 for Head of Household. See your bracket on our Income Tax Calculator.

Investing, Returns & Debt Repayment

What is the difference between CAGR and total ROI?

Total Return (ROI) measures simple cumulative gain regardless of duration. Compound Annual Growth Rate (CAGR) measures the geometric mean annualized return, providing an accurate year-over-year comparison against benchmark indices. Model your returns on our Investment Return Calculator.

Debt Avalanche vs. Debt Snowball: Which saves more money?

Mathematically, the Debt Avalanche (paying off highest-interest rate debts first) always saves the most interest and accelerates debt freedom fastest. The Debt Snowball (paying off lowest balance debts first) provides psychological momentum. Compare payoffs on our Debt Payoff Calculator and Credit Card Payoff Calculator.

How does DRIP accelerate dividend compounding?

A Dividend Reinvestment Plan (DRIP) automatically uses cash dividend distributions to purchase additional whole and fractional shares of stock. In subsequent quarters, those newly acquired shares generate their own dividends, creating an exponential compounding feedback loop. Simulate DRIP on our Dividend Calculator.

Ready to run your numbers?

Choose from 15 purpose-built financial calculators designed with verified formulas and 2026 US regulatory data.

Explore All 15 Calculators →