Estimate savings growth from an initial balance and end-of-month contributions. Compare a nominal annual rate compounded monthly with an effective annual rate.
Future value = P(1+i)^n + C((1+i)^n − 1)/i, where i is the monthly rate, n is months, P is the starting balance and C the monthly contribution. At zero interest, use P + Cn.
With 1,000 initially, no deposits and a 12% nominal annual rate compounded monthly, the balance after one year is about 1,126.83. At a 12% effective annual rate it is 1,120.00.
The rate is assumed constant and non-negative. Deposits are made at month end. Fees, tax, inflation and investment losses are excluded. An assumed growth rate is not a forecast or a guaranteed return. The table shows contributions separately from theoretical growth.
This tool places contributions at month end. Beginning-of-month contributions earn one additional month of growth; at a positive rate, that produces a higher ending balance.
With monthly compounding, 12% nominal means 1% each month. The factor is 1.01^12 ≈ 1.126825, giving about 12.6825% effective growth. A 12% effective annual rate already includes annual compounding effects.
English edition: 16 September 2026.