Savings Account Calculator with Daily Compound Interest — APY & Growth
Use this as a savings account calculator with interest compounded daily — the method many high-yield savings and money market accounts use. Three examples: (1) $10,000 at 4.5% compounded daily for 1 year grows to about $10,460 (APY ≈ 4.60%). (2) $25,000 at 4.5% with roughly $200/month added for 5 years can approach ~$45,000 depending on deposit timing. (3) The same 4.5% nominal rate compounds to a slightly lower APY if interest posts only monthly — daily compounding wins by a small but compounding edge. Enter principal, rate, horizon, and optional monthly deposits below.
Daily Compounding Results
Final Amount
$16,487
5.127% effective APY
Methodology and limitations
Last reviewed:
Methodology
Uses daily compounding with 365 periods per year and optional monthly contributions.
Limitations
Does not model bank posting dates, tiered rates, or fees.
Official sources
How Daily Compound Interest Works
Use this as a savings account calculator with interest compounded daily — the method many high-yield savings and money market accounts use. Three examples: (1) $10,000 at 4.5% compounded daily for 1 year grows to about $10,460 (APY ≈ 4.60%). (2) $25,000 at 4.5% with roughly $200/month added for 5 years can approach ~$45,000 depending on deposit timing. (3) The same 4.5% nominal rate compounds to a slightly lower APY if interest posts only monthly — daily compounding wins by a small but compounding edge. Enter principal, rate, horizon, and optional monthly deposits below.
Method used
This calculator compounds interest daily on the principal balance, adds monthly contributions at each compounding step, and reports final balance, total contributed, interest earned, and day-one daily interest for comparison.
Daily rate = APR ÷ 365; balance grows by (1 + daily rate) each day; contributions added monthly
Practical example
Example: $10,000 at 5% compounded daily for 10 years with $200 monthly contributions grows to about $42,000–$43,000 with roughly $22,000+ in interest earned depending on contribution timing.
- $10,000 principal
- 5% annual rate, daily compounding
- $200 monthly contribution, 10-year horizon
The output shows final balance, total contributed, interest earned, effective APY, daily rate, and day-one daily interest.
Assumptions
- Compounding occurs 365 days per year.
- Monthly contributions are added at the same interval throughout the term.
- Rate stays constant; no taxes or fees are deducted.
What this includes
- Daily compounding projection, monthly contributions, interest earned, APY equivalent, and day-one daily interest.
What this excludes
- Variable rates, withdrawal schedules, tax-deferred account rules, bank compounding cut-off times, and intra-month contribution timing differences.
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Frequently Asked Questions
What is the daily compound interest formula?
Future value with daily compounding is FV = PV × (1 + r/365)^(365 × t), where PV is principal, r is the annual rate as a decimal, and t is years. Example: $10,000 at 4.5% for one year → about $10,460, because APY = (1 + 0.045/365)^365 − 1 ≈ 4.60%. Each day interest is calculated on the running balance. This calculator shows APY, total interest, and growth snapshots.
How is daily compounding different from monthly?
Daily compounding applies interest 365 times per year; monthly applies it 12 times. At 5% nominal, daily APY is about 5.127% versus 5.116% monthly. On $10,000 for one year that is only a few dollars difference, but the gap widens with larger balances and longer horizons. Credit cards also use daily rates — a 22% APR card accrues interest much faster than a 4.5% savings account.
When do banks use daily compounding?
Many high-yield savings accounts, money market accounts, and some CDs compound daily while crediting interest monthly. Credit cards often use daily periodic rates on balances. Investment accounts may compound daily inside funds even when you see monthly statements. Always check whether the quoted rate is APR or APY and how often interest posts to your account.
How do I use this as a savings account calculator compounded daily?
Enter starting balance, annual rate, and time horizon with daily (365) compounding. Example path: $25,000 at 4.5% plus about $200 monthly deposits for five years can grow toward the mid-$40,000s depending on when deposits post. Results show final balance, interest earned, and APY — compare against monthly compounding at the same quoted rate.
Can I add monthly contributions with daily compounding?
Yes. Enter an optional monthly contribution and the calculator adds each deposit, then applies daily compounding on the running total. On $10,000 at 4.5% for one year with no contributions you earn about $460; adding deposits accelerates both principal and interest. Bank posting dates can differ slightly from this planning model.
Does this calculator show simple interest comparison?
Yes. Results include a simple-interest comparison using the same principal, contributions, and nominal rate without compounding. On $10,000 at 4.5% for one year, simple interest is $450 versus about $460 with daily compounding — the gap grows each year as interest earns interest.