Best Free Investment Calculators Online (2025)
Model compound interest, retirement savings, loan amortization, and investment growth with free calculators for investors and planners.
Guide Overview
The difference between a good financial decision and a great one often comes down to understanding compound growth and time value of money. These free investment calculators help you model retirement savings, compare loan options, and project investment returns so you can make informed decisions with confidence.
Focus: compound interest, retirement planning, loan analysis
The Power of Compound Interest Over Time
Albert Einstein may or may not have called compound interest the eighth wonder of the world, but the math speaks for itself. Investing $500 per month at 8 percent annual return for 30 years produces over $680,000, of which more than $500,000 is pure growth on your contributions. Our compound interest calculator lets you experiment with different amounts, rates, and time horizons to see how small changes in behavior today create massive differences in outcomes decades from now.
Retirement Planning: Are You Saving Enough?
The retirement savings calculator projects your nest egg based on current savings, monthly contributions, expected return, and years until retirement. It also factors in inflation to show your balance in today's purchasing power, which is the number that actually matters. If the result is lower than you need, the calculator shows how much additional monthly saving would close the gap. Starting early is the most powerful lever because each year of delay costs far more than a small increase in contributions.
Understanding Loan Amortization Schedules
An amortization schedule shows how each payment is split between principal and interest over the life of a loan. Early payments are heavily weighted toward interest, which is why paying extra principal in the first few years has an outsized impact on total interest paid. The amortization schedule generator produces a month-by-month breakdown for any loan amount, rate, and term. It also shows the total interest cost, which often shocks borrowers into considering shorter terms or extra payments.
SBA Loans and Business Financing
Small Business Administration loans offer favorable terms but come with specific requirements and fee structures. The SBA loan calculator models 7(a) and 504 loan programs with their unique guaranty fees, interest rate structures, and term lengths. Knowing your projected payment before applying helps you determine how much to borrow and whether the investment will generate enough return to service the debt comfortably.
Financial Health Ratios for Businesses
The debt-to-equity ratio and working capital are fundamental metrics that lenders and investors evaluate when assessing business health. A high debt-to-equity ratio signals over-leverage and risk, while insufficient working capital indicates potential cash flow problems. Our calculators compute these ratios from your balance sheet data and show how they compare to industry benchmarks. Monitoring these metrics quarterly helps you spot financial stress before it becomes a crisis.
Tools in This Guide
Use these tools in sequence based on your workflow needs.
Compound Interest Calculator
Project how savings and investments grow over time with compound interest, contributions, and rate assumptions.
Use tool →Investment Growth Calculator
Model portfolio growth using starting balance, recurring contributions, expected return, and time horizon.
Use tool →Retirement Savings Calculator
Estimate how much you need for retirement and whether current contributions keep you on track.
Use tool →ROI Calculator
Calculate return on investment, net gain, and ROI percentage for projects, marketing campaigns, or purchases.
Use tool →Inflation Calculator
Adjust historical prices for inflation and compare purchasing power across different years.
Use tool →Loan Amortization Schedule Generator
Generate full amortization schedules with principal/interest breakdown and payoff timeline.
Use tool →SBA Loan Calculator
Estimate SBA-style loan payments, total interest, and amortization profile.. Free online, browser-based tool with instant results and no signup.
Use tool →Debt-to-Equity Ratio Calculator
Calculate debt-to-equity ratio and evaluate capital structure risk.. Free online, browser-based tool with instant results and no signup.
Use tool →Working Capital Calculator
Calculate working capital and current ratio from short-term assets and liabilities.
Use tool →Line of Credit Interest Calculator
Estimate interest costs for revolving credit using draw amount, APR, and repayment timing.
Use tool →Frequently Asked Questions
How much do I need to save for retirement?
What is a realistic rate of return for investments?
How does paying extra principal save money on a loan?
What is a good debt-to-equity ratio?
How does inflation affect my investment returns?
What is working capital and why does it matter?
Last updated: June 1, 2025