Chapter 01 · Your starting point

Money terms in plain language

What do APY, real return or FIRE number mean? Short explanations of the terms used on Saver's Atlas, each linked to the matching tool.

401(k) APY (annual percentage yield) Broker CD (certificate of deposit) Compound interest CPI-U Emergency fund ETF (exchange-traded fund) Expense ratio FDIC insurance FIRE FIRE number HSA (health savings account) Index fund Inflation IRA (individual retirement account) Real return Roth account Safe withdrawal rate Savings rate Treasury bill (T-bill)

401(k)

A tax-advantaged retirement plan offered through your employer. Some employers add to your contributions (the employer match). 401(k), IRA & HSA →

APY (annual percentage yield)

The yearly yield of a savings account including compounding. It is the number to compare accounts by. Savings calculator →

Broker

The company through which you buy and hold stocks, ETFs and bonds. Brokers differ in fees, product range and protection of your assets. Compare brokers →

CD (certificate of deposit)

A term deposit: you lock money away for a fixed period at a fixed rate and pay a penalty for withdrawing early. Savings calculator →

Compound interest

Interest on your interest: earned interest itself starts earning interest. Over long periods the difference is large. Savings calculator →

CPI-U

The Consumer Price Index for All Urban Consumers from the BLS: the most widely used measure of US inflation. Inflation calculator →

Emergency fund

A cushion of instantly accessible cash for unexpected costs or lost income, usually expressed in months of essential spending. Emergency fund →

ETF (exchange-traded fund)

A fund that trades on an exchange and tracks an index such as a broad stock-market index. You buy and sell it through a broker. Compare brokers →

Expense ratio

The yearly cost of a fund as a percentage of the amount invested. It is deducted automatically from the fund's assets. Compare brokers →

FDIC insurance

US government insurance on bank deposits: up to $250,000 per depositor, per insured bank, per ownership category.

FIRE

Financial Independence, Retire Early: building enough capital that returns or withdrawals cover your spending, so working becomes optional. FIRE calculator →

FIRE number

The portfolio size at which it can cover your yearly spending. Often calculated as annual spending divided by a safe withdrawal rate. FIRE calculator →

HSA (health savings account)

A tax-advantaged account for medical costs, available with a high-deductible health plan. 401(k), IRA & HSA →

Index fund

A fund that copies a market index as cheaply as possible instead of trying to beat it. Compare brokers →

Inflation

The average rise in prices over a period. At 3% inflation, something that costs 100 today costs about 103 a year from now. Inflation calculator →

IRA (individual retirement account)

An individual tax-advantaged retirement account, separate from your employer. It comes in Traditional and Roth versions. 401(k), IRA & HSA →

Real return

Your interest or investment return minus inflation. It shows whether your purchasing power grows or shrinks, regardless of the balance on your statement. Savings calculator →

Roth account

You contribute after-tax dollars, but qualified future withdrawals are tax-free. The mirror image of the Traditional upfront deduction. 401(k), IRA & HSA →

Safe withdrawal rate

The share of your portfolio you can withdraw each year in the expectation that the money lasts long enough. It is a historical rule of thumb, not a guarantee. FIRE calculator →

Savings rate

The share of your income that you save or invest. Together with your return it determines how fast your wealth grows. Questionnaire →

Treasury bill (T-bill)

Short-term US government debt (up to one year) sold at a discount and repaid at face value. Rates & inflation →

General explanations, not personal financial advice. Rules and limits are shown with sources on the tool pages.