Junior Savings Calculator

100/month from birth to age 18 at 6% compounds to about 38,700. Starting at age 10 gives about 12,300, under a third as much, because the deposits run for 96 months instead of 216. Matching the from-birth figure on a start at age 10 takes roughly 315/month, over three times the deposit. Most of the difference comes from elapsed time rather than deposit size.

Run it with sensible defaults

Using monthly savings of 100, child's current age of 4, annual return of 6%, the calculation works out to 26,230.48. These example values are a starting point, not a recommendation.

The levers in this calculation

Monthly Savings is the larger lever: a 1% change in it moves Pot at Age 18 by about 1%, against 0.42% for Child's Current Age in the opposite direction.

Monthly Savings scales the result in a straight line: double the deposit and the pot doubles, whatever else is set. The age input compounds instead. At 100 a month and 6%, a start at age 4 reaches 26,230 over 168 months, a start at age 8 reaches 16,388 over 120 months, and a start at age 12 reaches 8,641 over 72 months. Each four years removed costs more than the deposits themselves, because the earliest deposits are the ones with the longest runway.

The same effect shows in how much of the pot is growth rather than money paid in. From birth, 21,600 of deposits becomes 38,735, so growth is 44% of the total. From age 4, 16,800 becomes 26,230 and growth is 36%. From age 12, 7,200 becomes 8,641 and growth is under 17%. The later the start, the more the pot is simply the deposits handed back.

Annual Return sits between the two. From age 4, moving 6% to 7% adds about 2,170, and dropping to 5% takes off about 1,970. Over shorter horizons the rate matters less, since there is less time for the gap to compound.

How the math works

The projection uses the future value of an ordinary annuity. Each monthly deposit compounds forward at the monthly equivalent of the annual rate, meaning the annual figure divided by 12, for however many months remain until the child turns 18. With 168 months to run, the earliest deposit compounds for 167 of them; a deposit made in the final month does not compound at all. Adding up every deposit's grown value produces the closed form shown in the formula section. Deposits are treated as landing at the end of each month, which is the more conservative convention. Assuming start-of-month deposits would raise the figure by roughly one month of growth.

Turning the result into a plan

A projection assumes the deposits happen every month for the full term, which is the assumption most likely to break in practice. Automatic transfers dated shortly after payday are one method savers use to keep contributions consistent, since the money moves before it is available to spend elsewhere. The calculator has no way to model missed months. A year of skipped deposits early in the term removes both those contributions and every year of growth they would otherwise have earned.

Related calculations worth running

The Compound Interest Calculator, the College Savings Calculator and the Education Savings Calculator cover adjacent parts of the same question. Running two or three of them together shows where a single assumption is carrying more weight than it first appears.

Worked example

A child is currently 8 years old. A parent plans to save 150 per month until age 18 (10 years). The account earns an annual return of 5%. The calculator models monthly deposits compounding over that decade. The result shows approximately 23,292 at age 18, of which 18,000 is deposits and roughly 5,292 is accumulated return. This illustrates how time remaining, deposit frequency, and return rate interact to shape the final balance.

Breaking down the example

• Time horizon: 10 years (120 months)
• Total contributions: 18,000 (150 × 120)
• Projected accumulated returns: roughly 5,292
• Projected balance at 18: approximately 23,292

Common scenarios where this matters

This calculator applies in several contexts. Parents or guardians saving for a child's education expenses often model outcomes across different monthly amounts and time horizons. Families inheriting funds for a minor child use it to understand growth potential if left untouched versus receiving installments. Grandparents setting up regular gifts track how contributions accumulate over the years until the child reaches 18. In each case, the projection helps illustrate how early action and consistent deposits interact with compound returns.

What the result shows and does not show

The calculator displays an estimate of the savings pot at age 18 based on the inputs entered. It models the mathematical effect of regular monthly contributions and a constant return rate applied over time. It does not account for inflation, changes in contribution amounts, variability in actual returns, taxes on interest earned, or withdrawals before age 18. It also does not model the impact of account fees or product-specific terms. The output is illustrative and educational; actual outcomes depend on product selection, economic conditions, and adherence to the saving plan.

For educational illustration

This calculator is a tool for modelling savings growth under consistent assumptions. Results are estimates only and do not predict actual returns or guarantee outcomes.