Savings & Investment Calculators
Seven calculators for money you are growing rather than borrowing — compounding, targets, returns and the quiet drag of inflation.
Compounding is the whole game
The difference between simple and compound interest looks trivial in year one and enormous in year twenty. Simple interest is charged on the original principal only; compound interest is charged on the balance including previous interest, so growth accelerates. Compare the two directly with the Simple Interest and the Compound Interest — same inputs, very different endings.
Goal-first or growth-first?
There are two ways to plan. Growth-first asks “what will this become?” — that is the Compound Interest and the Retirement. Goal-first asks “what do I need to put in?” — that is the Savings Goal, which works backwards from a target and a date to a monthly contribution. Most people find the second more useful, because it produces an action rather than a number.
Measuring what you already did
For a completed investment, the ROI Calculator gives the plain percentage return, and the Investment Return gives the annualised rate (CAGR) — the figure that lets you compare an eighteen-month holding against a five-year one. A 40% total return over five years is a very different investment from 40% in one year, and only the annualised figure makes that visible.
Do not forget inflation
A projection in today's money is optimistic by definition. The Inflation Calculator converts a future sum back into present-day purchasing power, which is the honest way to read any long-range retirement or savings projection. As a rule of thumb, subtract inflation from your assumed growth rate before you decide whether a plan works.