Savings Goal Calculator: How Long, or How Much a Month?

A savings goal without a number attached to it is a wish. Attach a target, a start and a timeframe, and it becomes a plan you can test. This calculator answers the two questions people ask most: how long will it take, and how much do I need to put aside each month?

How to use this calculator

1. Choose what you want to find: how long it will take, or how much to save each month.
2. Enter your savings goal.
3. Enter the amount you already have.
4. Enter either your monthly contribution or the years you have, depending on the mode.
5. Enter an assumed annual growth rate, or zero if you would rather ignore growth.

The formulas

The calculator uses a monthly growth rate equal to the annual rate divided by twelve.

Time to a goal. It adds up the balance month by month: balance = balance × (1 + monthly rate) + monthly contribution, and stops in the first month the balance reaches the goal.

Monthly amount needed. Over n months, with a monthly rate r:

• Monthly amount = (goal − starting amount × (1 + r)^n) × r ÷ ((1 + r)^n − 1)

With zero growth this simplifies to (goal − starting amount) ÷ n. In both modes, the calculator is tested against the standard annuity formula, and the monthly amount it finds is checked by plugging it back in to confirm the balance lands on the goal.

How to read your result

The headline is the answer to your question. Below it, you will see how much of the final balance is your own money and how much is growth. For modest goals over a few years, most of the balance is what you paid in, which is a useful reminder that saving rate matters more than returns over short periods.

If the result is longer than you hoped, you have three levers: a larger contribution, a lower goal, or more time. It is tempting to reach for a higher assumed growth rate instead, but that only makes the plan look better on paper. A plan that works at zero growth does not depend on markets behaving.

Cash or investments?

Where the money sits changes both the growth and the risk. Money you will need within a few years generally belongs somewhere stable, because investments can fall in value just as you need them. Money for goals many years away can tolerate more risk, in exchange for the possibility of higher returns that are never guaranteed. This tool does not tell you which is right for you. Our guides to investing for beginners and investment apps explain the trade-offs, and for long-term projections with fees and inflation, use the compound interest calculator.

A note for people with irregular income

Uneven income makes a buffer more valuable. A common goal for freelancers and side hustlers is a cash reserve covering several months of essential costs, so a slow stretch does not force bad decisions. Setting the goal to your monthly costs multiplied by the number of months you want covered, then choosing a realistic contribution, gives you a concrete plan. In good months you can contribute more, and the calculator will show how much sooner you reach the goal. Keeping records of your earnings helps you set realistic contributions; see our guide to tracking online income and taxes.

Common mistakes

Assuming high growth. Optimistic returns make a plan look fast and fragile.

Ignoring inflation. A goal set today may cost more later, so revisit it periodically.

Forgetting to pay yourself first. Contributions that depend on what is left over often do not happen. Automating a transfer helps.

Treating the goal as fixed. Circumstances change, so review the numbers every few months.

Investing money you need soon. Short-term goals and market risk do not mix well.

Assumptions and limits

The calculator assumes a steady growth rate and a steady monthly contribution made at the end of each month. It ignores tax on interest or gains, fees, changing contributions and inflation. It stops at one hundred years. It is a planning aid and general information, not financial advice, and real returns can differ greatly from the assumption you enter.