Savings Plan Calculator
Monthly deposit needed to reach a goal within a given time.
How it works
PMT = (target − current×(1+i)ⁿ) × i ÷ ((1+i)ⁿ − 1), i = annual÷12
Accounts for growth of current savings, then backs out the monthly top-up. If already funded, the result is ≤ 0.
Worked example
Target 500,000 over 20 years at 5% (0.4167%/month):
monthly = 500000 ÷ (((1.004167)^240 − 1) ÷ 0.004167) ≈ 1,217.
With only 10 years left you would need about 3,220/month — half the time, nearly triple the deposit.
Notes and limitations
This assumes end-of-month deposits and a constant return. Real returns vary; starting earlier is what keeps the monthly amount small — the most practical face of compounding.