About Sumly

Why Sumly exists

Most financial calculators online either do too little (a single number with no explanation) or too much (a sign-up wall, a sales pitch, a "free consultation"). Sumly sits in between. Each calculator answers one specific question people actually ask:

• How much do I really need to retire? This works backward from your real monthly expenses instead of a generic multiple of salary.
• What will compounding actually do? This shows your result at every rate from 0% to 25%, so you can see how much a rate assumption matters.
• Where does my net worth stand? This compares your number with Federal Reserve data for people your age.
• When should I claim Social Security? This compares 62, full retirement age and 70, with break-even ages.
• Roth or traditional? This compares after-tax retirement value at your tax rates.
• How is inflation affecting me? This shows what money from any year is worth today, and your personal inflation rate based on how you spend.
• How fast can I get out of debt? This shows payoff time and interest saved with an extra payment.
• Is borrowing against my assets better than selling them? This models the "Buy, Borrow, Die" strategy, risks included.

How the calculators are built

Every calculator runs entirely in your browser. Nothing you type is sent to a server, saved or seen by anyone, including us. The formulas are standard financial math: monthly compounding for growth, and simple, transparent assumptions for taxes and borrowing. Wherever a calculator uses outside data, such as median net worth by age, we cite the source on the page.

We publish exactly how each calculator works, including its simplifications and limitations, on our methodology page. If a calculator makes a simplifying assumption, we'd rather tell you than hide it.

Honest about risk

Strategies like borrowing against a portfolio can look great in a calculator and go badly in real life. Where a strategy has real downside, such as margin calls, variable interest rates or overly optimistic growth assumptions, the calculator and our guides say so plainly.

What Sumly is not

Sumly is an educational tool. It isn't a financial advisor, tax preparer, broker or lender. We don't sell financial products, and we aren't paid to recommend any. The results are illustrations based on the assumptions you enter, not predictions or advice. For decisions with real consequences, such as retirement timing, borrowing against assets or estate planning, talk to a qualified professional. See our disclaimer.

How Sumly is funded

Sumly is free and supported by advertising served by Google AdSense. Advertisers have no influence over our calculators or guides. See our privacy policy for how advertising cookies work.

Get in touch

Found an error, want a calculator added, or have feedback? Email contact@trysumly.com or visit our contact page.