Compound interest and savings calculator

Illustrate the theoretical growth of a balance using an entered rate and regular contributions.

SumHexa explains a mathematical formula and provides this calculator for informational purposes. It does not recommend taking out a loan or making an investment, and it does not promise or encourage an interest return. Results are theoretical, based on the assumptions entered, and exclude fees, taxes, risks and the actual terms of any financial product.

Method and assumptions

Method version 1.0.0 · Updated October 2, 2026

Calculate projection

Formula: Future balance = compounded starting balance + compounded end-of-period contributions.

Mathematical projection excluding fees, taxes and inflation.

principal: Starting balance
contribution: Contribution per period
annualRatePercent: Annual rate (%)
years: Duration (years)
frequency: Contribution frequency

Contributions are assumed to occur at the end of each period. The nominal annual rate is divided across periods. Fees, taxes, inflation and rate changes are excluded.

Calculate with code

These short examples use the same inputs and core calculation as this tool. Adapt validation and formatting to your application.

JavaScript

const principal = 1000, annualRate = 0.05, years = 3;
console.log(principal * (1 + annualRate) ** years); // 1157.625

TypeScript

const principal = 1000, rate = 0.05, years = 3;
const futureValue: number = principal * (1 + rate) ** years;
console.log(futureValue); // 1157.625

Python

principal, rate, years = 1000, 0.05, 3
print(principal * (1 + rate) ** years)  # 1157.625

Java

double value = 1000 * Math.pow(1.05, 3);
System.out.println(value); // 1157.625

double value = 1000 * Math.Pow(1.05, 3);
Console.WriteLine(value); // 1157.625