Compound Interest Calculator – Future Value & Growth
Project savings and investments with compounding. Add monthly contributions, pick compounding frequency, and see future value with clear maths and examples.
⚠️ Advisory only: Results are educational estimates. For financial decisions, verify with a qualified professional.
Calculate Compound Growth Over Time
Why Use This Compound Interest Calculator?
Calculate Future Value with Contributions
One-off and monthly/annual contributions supported.
Choose Compounding Frequency (Daily, Monthly, Yearly)
Annual, quarterly, monthly, weekly, or daily compounding.
View Effective Annual Return (EAR %)
Shows nominal vs effective rate from chosen frequency.
Save or Share Your Results
Copy a link that preserves inputs and results.
3-Step Process to Calculate Compound Interest
Enter Starting Balance or Investment Amount
Add optional monthly or annual contributions.
Set Interest Rate & Contribution Frequency
Choose annual rate and how often it compounds.
Review Future Value & Growth Results
See total contributions, interest earned, and final balance.
How to Use This Compound Interest Calculator
How Compound Interest Works (Explained Simply)
Compound interest means you earn interest on both your original principal and the interest already added. The more often it compounds (monthly vs annually), the faster your balance can grow. Regular contributions boost the effect further, especially when made at the start of each period.
Formulas Used (With Worked Example)
- Future Value (no periodic deposits):
FV = P(1 + r/m)^{m·t} - Future Value (with deposits PMT at end of period):
FV = P(1 + r/m)^{m·t} + PMT · \frac{(1 + r/m)^{m·t} - 1}{r/m} - Future Value (with deposits PMT at beginning): multiply the deposit term by
(1 + r/m). - Effective Annual Rate (EAR):
EAR = (1 + r/m)^{m} - 1
Worked example: Principal P = £5,000; Annual rate r = 6% (0.06); Monthly compounding (m=12); Term t = 10 years; Monthly deposit PMT = £100 at end of month.
Growth factor = (1 + 0.06/12)^(12·10) ≈ 1.7908.
FV principal ≈ £5,000 × 1.7908 = £8,954.
FV deposits ≈ £100 × [(1.7908 − 1)/(0.06/12)] ≈ £100 × 158.16 = £15,816.
Total FV ≈ £8,954 + £15,816 = £24,770. (Illustrative; your actual result depends on the exact inputs.)
Assumptions: Constant rate, fixed contributions, no fees or taxes. Use the calculator to reflect your real schedule and contribution timing.
Compound Interest Calculator – FAQs
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