Interest Rate Calculator

The interest rate calculator converts between nominal and effective rates, and calculates the actual interest cost or earnings on a given balance. A nominal rate is the stated rate before accounting for compounding frequency. An effective rate shows what you actually earn or pay when compounding is factored in. For savings accounts, effective rates are what matter for comparing products. For loans, understanding whether a stated rate is nominal or effective prevents you from being misled by headline figures.

Enter the nominal interest rate and compounding frequency to calculate the effective annual rate. Alternatively, enter a balance and rate to calculate the interest amount. The calculator handles monthly, quarterly, semi-annual and daily compounding, converting all to a common effective annual basis for accurate comparison.

Comparing savings accounts or loan products that use different compounding frequencies.
Converting a nominal rate to effective for accurate yield comparison.
Calculating actual interest earned or charged on a specific balance.
Understanding whether a lender's quoted rate is nominal or effective before signing.

Nominal Rate: The stated annual interest rate before accounting for compounding frequency, often lower than the effective rate.

Effective Rate: The actual annual rate after compounding, reflecting the true cost of borrowing or true return on savings.

Compounding Frequency: How often interest is calculated and added to the balance, daily, monthly, quarterly or annually.

Never compare financial products using only their nominal rates without checking compounding frequency. A savings account paying 4.8 percent monthly compounding delivers a higher effective return than one paying 5 percent annually. Always convert all rates to effective annual rates before comparison.

Use alongside the Savings Calculator to project balances using the correct effective rate. The Loan Calculator will show total interest cost using the effective rate.

Frequently Asked Questions

A Sharpe ratio above 1.0 is generally considered good, meaning you earn more than one unit of excess return for each unit of risk. Above 2.0 is very good; above 3.0 is exceptional and often indicates either a genuinely superior strategy or measurement issues such as using too short a data period. Global equity indices have historically delivered Sharpe ratios of 0.3 to 0.5 over long periods. Hedge funds targeting Sharpe ratios above 1.0 are pursuing what most active managers cannot consistently sustain. When comparing funds or strategies, always use Sharpe ratios calculated over the same time period and benchmark.

Systematic risk, also called market risk, affects all investments and cannot be eliminated through diversification. Economic recessions, interest rate changes and geopolitical events are systematic risks. Unsystematic risk, also called idiosyncratic or specific risk, affects individual companies or sectors and can be reduced through diversification. Holding 20 to 30 uncorrelated stocks eliminates most unsystematic risk. The key insight from modern portfolio theory is that only systematic risk is compensated by higher expected returns, investors are not rewarded for taking unsystematic risk that could have been diversified away.

Value at Risk (VaR) estimates the maximum loss over a given period at a specified confidence level, for example, a 95 percent one-day VaR of €50,000 means you expect to lose no more than €50,000 on 95 out of 100 trading days. The critical limitation is that VaR says nothing about losses beyond the confidence threshold, the 5 percent of days not covered. In financial crises, losses frequently far exceed VaR estimates because the assumptions of normal return distributions break down precisely when tail risks materialise. VaR is best used as one risk metric among several, not as a standalone measure of portfolio risk.

A beta of 1.5 means your portfolio or investment moves 1.5 times as much as the market, in both directions. If the market falls 20 percent, a 1.5 beta portfolio would be expected to fall approximately 30 percent. High-beta portfolios outperform in strong bull markets and underperform significantly in bear markets. A beta below 1 indicates less sensitivity to market movements, defensive sectors like utilities and consumer staples typically have betas of 0.5 to 0.8. Beta is calculated from historical data and assumes the future relationship with the market will mirror the past, which is not always the case, particularly when a company's business model changes significantly.

CAPM remains the most widely taught and used framework for estimating the required return on an investment, despite well-documented empirical limitations. The model predicts that expected return equals the risk-free rate plus beta times the market risk premium. In practice, factors beyond beta, such as size, value, momentum and profitability, have been shown to explain additional return variation that CAPM misses. The Fama-French multi-factor models extend CAPM to capture these additional risk factors. For practical corporate finance and investment analysis, CAPM is used as a starting point and supplemented with judgment and sector-specific knowledge rather than applied mechanically.