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HoldingCost

Monthly savings required calculator

Calculate the monthly contribution needed to hit a savings goal by a chosen date.

Calculator personal

Logic updated April 2026

This calculator solves the inverse savings problem: given a future-value goal, current savings, an annual interest rate, and a fixed timeframe in months, what's the monthly contribution required to hit the target? It uses the standard ordinary-annuity formula and produces a month-by-month schedule showing how the balance grows from today to your goal.

How this is calculated

Formula 

PMT = (FV − PV × (1+r)^n) × r / ((1+r)^n − 1)   where r is monthly rate, n is months, FV is goal, PV is current savings

Step-by-step

  1. Convert the annual interest rate to a monthly rate by dividing by 12
  2. If current savings already meets or exceeds the goal, return $0/month required (no further saving needed)
  3. Otherwise apply the ordinary-annuity formula above to back-solve the required monthly contribution
  4. For zero-interest scenarios, the formula collapses to (FV − PV) ÷ n — pure linear division
  5. Build a month-by-month schedule showing balance, contribution, and interest earned at each step
  6. Verify the final balance meets the target — small rounding adjustments may produce a balance slightly above the goal
Rounding mode
ROUND_HALF_UP
Precision
20-digit internal precision (Decimal.js), rounded to 2 decimal places for display
Logic last reviewed

Assumptions & limitations

What this calculator assumes

  • Monthly compounding — interest applied once per month
  • Contributions are made at the end of each month (ordinary annuity)
  • Zero interest case uses simple linear division
  • When existing savings already exceed the goal, required contribution is $0

What this calculator doesn’t account for

  • Doesn't model variable interest rates over the saving period
  • Doesn't include any account fees that would reduce the effective return
  • Doesn't factor in tax on interest earned
  • Doesn't account for inflation eroding the purchasing power of the goal
  • Assumes a constant contribution — variable monthly amounts aren't modelled

Worked example

Saving for a $50,000 deposit in 4 years (48 months) starting from $5,000, earning 4% annually compounded monthly.

Input Value
Goal amount $50,000
Current savings $5,000
Timeframe 48 months
Annual rate 4%

Required monthly contribution: ~$845

Monthly rate: 4% ÷ 12 = 0.333%. Future-value of $5,000 over 48 months: $5,000 × (1.00333)^48 ≈ $5,866. Gap to fill: $50,000 − $5,866 = $44,134. Annuity factor: ((1.00333)^48 − 1) ÷ 0.00333 ≈ 51.96. Required monthly: $44,134 ÷ 51.96 ≈ $849. The $5,000 starting position grows to $5,866 from interest alone over 4 years, while $849/month over 48 months grows to ~$44,150 with interest, totalling roughly $50,000.

Frequently asked questions

How much do I need to save each month?

It depends on your goal, timeframe, current savings, and assumed return — the calculator backs into the exact figure for your inputs. As a rule of thumb: to reach $X in N years from zero with no return, save X ÷ (N × 12) per month. Add interest and the figure drops; longer horizons drop it dramatically. The shorter the timeframe, the more the answer is dominated by raw saving rather than growth.

How does the time horizon affect required savings?

Longer horizons reduce the required monthly contribution non-linearly — interest does more of the work. To reach $50,000 from zero at 5% return: 5 years requires ~$735/month, 10 years requires ~$322/month, 20 years requires ~$121/month. Doubling the horizon reduces the required contribution by more than half, because earlier savings compound for longer.

What return rate should I assume?

For short timeframes (under 5 years), use a conservative savings-account rate (currently 3–5%). Money you'll need within 5 years shouldn't be in volatile investments. For longer timeframes (10+ years), a balanced portfolio at 5–7% is reasonable. The rate matters less for short horizons (where contributions dominate) and more for long horizons (where compounding dominates).

What if I already have some savings?

The calculator factors that in via the 'current savings' input. The starting balance grows at the rate over the timeframe, reducing how much of the goal you need to fund through new contributions. For example, $10,000 at 5% over 10 years grows to ~$16,300 — that's $6,300 of 'free' progress toward your goal that the calculator credits to you.

Why is my required savings higher than the goal divided by months?

It usually isn't — it's lower, because interest does some of the work. If your inputs include a meaningful current balance or a multi-year timeframe at a positive rate, the required monthly is below (goal ÷ months). If it's higher, check your inputs — you may have entered the goal as a dollar figure but the timeframe in years instead of months.

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