10 Financial Ratios Everyone Should Know

Financial ratios transform raw numbers into meaningful relationships. They are the language that financial professionals use to assess health, risk, and value — but most of the most important ratios are simple enough to calculate in a few seconds and powerful enough to immediately reveal whether a financial situation is sustainable. You do not need an accounting degree to use them; you need to know which ratios matter and what the numbers mean.

Debt-to-Income Ratio: Your Personal Credit Health Score

The debt-to-income ratio (DTI) compares your total monthly debt payments to your gross monthly income. It is one of the first things a mortgage lender calculates.

DTI = Total monthly debt payments ÷ Gross monthly income

A monthly income of $6,000 with $2,100 in debt payments (mortgage $1,500 + car loan $400 + student loan $200) gives a DTI of $2,100 ÷ $6,000 = 35%.

General guidelines: - Below 36%: Healthy; most lenders comfortable - 36–43%: Acceptable for most mortgage products - Above 43%: Difficulty qualifying for prime mortgages; financial stress likely - Above 50%: High financial distress; immediate debt reduction warranted

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Savings Rate: The Single Best Measure of Financial Progress

Your savings rate is the percentage of your income that you save and invest. Unlike net worth (which takes years to build), savings rate is something you can improve immediately and its effects compound powerfully over time.

Savings rate = (Income − Spending) ÷ Income

On an income of $60,000 per year spending $48,000, your savings rate is ($60,000 − $48,000) ÷ $60,000 = 20%.

Why savings rate matters so much: a 50% savings rate means you are saving one year of expenses for every year you work, so you could theoretically reach financial independence in 17 years from scratch (based on a 7% real return). A 10% savings rate takes over 40 years. The difference is not a small adjustment — it is the difference between working until 65 or working until 50.

Expense Ratio: The Invisible Tax on Investments

An expense ratio is the annual fee charged by a mutual fund or ETF, expressed as a percentage of assets under management.

Annual cost = Portfolio value × Expense ratio

A $100,000 portfolio in a fund with a 1.5% expense ratio costs $1,500 per year. A similar fund with a 0.05% ratio costs $50. Over 30 years, the difference compounds dramatically:

• $100,000 at 7% gross return in a 1.5% expense fund: approximately $574,000 after 30 years (net 5.5% return)
• $100,000 at 7% gross return in a 0.05% expense fund: approximately $757,000 after 30 years (net 6.95% return)

That $1.45% difference in annual fee costs $183,000 over the investment horizon — entirely for the privilege of paying more. Always check expense ratios before investing in a fund.

Compound Interest Compound Interest

Emergency Fund Ratio: Months of Coverage

The emergency fund ratio measures how many months of essential expenses your liquid savings can cover.

Emergency fund ratio = Liquid savings ÷ Monthly essential expenses

Essential expenses (not total spending) include housing, food, utilities, transport, and insurance — not discretionary items. With $15,000 in savings and $3,500/month in essential expenses, the ratio is 15,000 ÷ 3,500 = 4.3 months.

Standard guidance: 3–6 months for stable employment; 6–12 months for self-employed, variable income, or single-income households.

Housing Cost Ratio: Affordability in One Number

The housing cost ratio is the percentage of gross income spent on housing.

Housing cost ratio = Monthly housing costs ÷ Gross monthly income

Housing costs should include mortgage or rent, property taxes, insurance, and (for apartments) body corporate fees. The traditional guideline is no more than 28% of gross income — though this threshold was established decades ago and may not reflect housing market realities in many cities.

A more sustainable individual benchmark: housing costs you can sustain if your income dropped 20% temporarily.

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Price-to-Earnings Ratio: Equity Valuation Simplified

The P/E ratio compares the price of a stock (or the stock market as a whole) to its earnings per share.

P/E = Share price ÷ Earnings per share (EPS)

A stock trading at $80 with annual earnings of $5 per share has a P/E of 80 ÷ 5 = 16. You are paying $16 for each $1 of annual earnings. A higher P/E implies the market expects higher future earnings growth; a lower P/E implies modest expectations or undervaluation.

Historical average P/E for the US stock market (S&P 500) is approximately 15–17. P/E ratios well above that historical average imply significant growth expectations are already priced in. This does not mean a high-P/E stock is overpriced — growth expectations may be justified — but it does mean the margin for error is smaller.

Loan-to-Value Ratio: Your Mortgage Equity Cushion

The loan-to-value ratio (LTV) measures how much of a property is financed by debt.

LTV = Loan amount ÷ Property value

A $360,000 mortgage on a $400,000 property gives an LTV of 360,000 ÷ 400,000 = 90%. The owner's equity is 10%.

LTV matters for: - Mortgage insurance requirements: LTV above 80% typically triggers mandatory mortgage insurance - Interest rate pricing: Higher LTV = higher rate in most markets - Financial resilience: If property values fall 15%, a 90% LTV borrower is in negative equity; an 80% LTV borrower still has a 5% cushion

LTV decreases as you make mortgage payments and as property values rise — tracking it annually tells you when you can cancel mortgage insurance or refinance at a better rate.