Why does compounding frequency barely change the answer?

Because APY already includes it. Once two accounts are both quoted in APY, daily-compounding 4.50% and monthly-compounding 4.50% produce the same final balance — by definition. The compounding frequency only matters when the bank quotes you a nominal rate; APY normalizes it away.

How much is FDIC insurance?

FDIC insures up to $250,000 per depositor, per insured bank, per ownership category. That means a single account holder gets $250k coverage, a joint account gets $500k ($250k × 2), and you can multiply coverage by spreading deposits across multiple FDIC-insured banks. Credit-union accounts have parallel NCUA coverage with the same limits. The calculator flags when your projected balance exceeds the single-bank limit.

Is a savings account losing me money to inflation?

Sometimes — when APY is below inflation, the real (after-inflation) balance grows slower than the nominal balance, and if the gap is wide enough, real value actually falls. With 4.50% APY and 3% inflation, the real return is roughly +1.5% per year — modest positive real growth. With 0.5% APY (still the national average for ordinary savings) and 3% inflation, you are losing about 2.5% of purchasing power per year — which is why high-yield online savings matters.

How is this different from a CD calculator?

A Certificate of Deposit (CD) locks the APY for a defined term and usually disallows additional deposits and imposes an early-withdrawal penalty. A savings account is liquid — you can add deposits any time and withdraw on demand. This calculator models the liquid savings case (with optional monthly deposits). For a fixed-term CD, set monthly deposits to $0 and use the disclosed CD APY.

Why does compounding frequency barely change the answer?

Because APY already includes it. Once two accounts are both quoted in APY, daily-compounding 4.50% and monthly-compounding 4.50% produce the same final balance — by definition. The compounding frequency only matters when the bank quotes you a nominal rate; APY normalizes it away.

How much is FDIC insurance?

FDIC insures up to $250,000 per depositor, per insured bank, per ownership category. That means a single account holder gets $250k coverage, a joint account gets $500k ($250k × 2), and you can multiply coverage by spreading deposits across multiple FDIC-insured banks. Credit-union accounts have parallel NCUA coverage with the same limits. The calculator flags when your projected balance exceeds the single-bank limit.

Is a savings account losing me money to inflation?

Sometimes — when APY is below inflation, the real (after-inflation) balance grows slower than the nominal balance, and if the gap is wide enough, real value actually falls. With 4.50% APY and 3% inflation, the real return is roughly +1.5% per year — modest positive real growth. With 0.5% APY (still the national average for ordinary savings) and 3% inflation, you are losing about 2.5% of purchasing power per year — which is why high-yield online savings matters.

How is this different from a CD calculator?

A Certificate of Deposit (CD) locks the APY for a defined term and usually disallows additional deposits and imposes an early-withdrawal penalty. A savings account is liquid — you can add deposits any time and withdraw on demand. This calculator models the liquid savings case (with optional monthly deposits). For a fixed-term CD, set monthly deposits to $0 and use the disclosed CD APY.

Savings Calculator

Project a bank or HYSA balance with APY, monthly deposits, and inflation-adjusted real value.

Result

Balance after 5 yrs

$22,978.85

Total deposited$5,000 initial + 60 × $250 monthly$20,000.00
Interest earned$2,978.85
Effective APYcompounded daily4.500%
Real value (after inflation)today's purchasing power at 3.0% inflation$19,821.76
Real premium over depositsreal value ÷ deposited − 1-0.89%
FDIC coverageWithin $250k FDIC limit per bank.

Losing purchasing power — APY < inflation

Your plan

4.50% APY × 5 yrs

$22,978.85

Same plan, no monthly deposit

loses $16,747.94 from contributions and their compounding

$6,230.91

Same plan @ 0.5% APY (national avg savings)

why HYSAs matter — same deposits, far less interest

$20,311.70

Real (inflation-adjusted) value

today's purchasing power

$19,821.76

Source: Truth in Savings Act / Regulation DD (12 CFR 1030) — defines APY and disclosure standards; FDIC Deposit Insurance ($250k per depositor/bank).

Not financial advice — Projection assumes the APY stays constant — real-world HYSA rates fluctuate with the federal funds rate. FDIC insurance covers the principal + accrued interest up to $250,000 per depositor per insured bank. For balances above that, split across institutions.

How to use this calculator

Enter your starting balance and any monthly deposit.
Use the APY as quoted by the bank (NOT the simple rate) — Reg DD requires US banks to disclose APY on every deposit-account ad and statement.
Pick the compounding frequency the bank lists; daily is the US default for high-yield savings.
Adjust expected inflation to see how your real (purchasing-power) balance compares to nominal.

About this tool

A savings calculator projects what a bank deposit will grow to over time given an Annual Percentage Yield (APY), a stream of additional deposits, and how often interest compounds. APY is the standard disclosure under the Truth in Savings Act (Regulation DD, 12 CFR 1030) — it already includes compounding, so a 4.50% APY account paying interest daily and a 4.50% APY account paying interest monthly end up at the same balance over a year by definition. This calculator returns the future nominal balance, the breakdown of deposits vs. interest, and the inflation-adjusted real value (purchasing power in today's dollars) so you can see whether a savings rate is actually beating inflation. It also flags whether your final balance crosses the $250,000 per-depositor-per-bank FDIC insurance limit.

What this calculator does

Projects the future balance of a deposit account given an APY (as disclosed under Truth in Savings / Reg DD), an optional monthly contribution, a compounding frequency, and a holding period. Also computes the inflation-adjusted real value of the final balance so you can see whether the account is actually beating inflation, and flags whether the projected balance crosses the $250,000 per-depositor-per-bank FDIC insurance limit.

How it works — the formula

Future value of initial deposit:
  FV_P = P · (1 + APY)^t       (in years)

Future value of monthly deposits (annuity-due of regular contributions):
  monthlyEffRate = (1 + APY)^(1/12) − 1
  FV_M = m · ((1 + monthlyEffRate)^months − 1) / monthlyEffRate

Real value adjustment:
  Real FV  = FV_total / (1 + inflation)^t

Because APY already incorporates compounding within the year, the geometric form (1 + APY)^t gives the same answer regardless of the bank's stated compounding frequency — which is exactly the point of the Truth-in-Savings standardization. Monthly deposits are aggregated with the monthly-equivalent rate derived from APY. The real-value step divides nominal future value by the cumulative inflation factor over the same horizon, returning the purchasing power of the final balance in today's dollars.

Sources: 12 CFR Part 1030 (Regulation DD) — Truth in Savings · Truth in Savings Act (12 USC 4301-4313) · FDIC — Are My Deposits Insured? (Deposit Insurance Coverage) · NCUA — Share Insurance Estimator (parallel coverage for credit unions)

Worked examples

Example 1

HYSA with monthly deposits, 5 years

Inputs:: initial = $5,000; monthly = $250; APY = 4.50%; daily compounding; 3% inflation
Output:: FV_P = 5000·(1.045)^5 ≈ $6,231; FV_M ≈ $16,800 (60 monthly deposits compounded at ~0.367%/mo); total balance ≈ $23,030; real value ≈ $19,860; total deposited = $20,000; real premium ≈ −0.7%

A 4.50% APY barely beats 3% inflation; the real balance is essentially preserved purchasing power, not real growth.

Example 2

Lump-sum CD, 5 years

Inputs:: initial = $50,000; monthly = $0; APY = 5.00%; annual compounding; 3% inflation
Output:: FV = 50000·(1.05)^5 = $63,814; real value ≈ $55,062; real premium ≈ +10.1%

Locking in a 5.0% APY when inflation runs 3% gives ~2% real return per year — a strong defensive allocation.

Example 3

Low-APY ordinary savings

Inputs:: initial = $10,000; monthly = $100; APY = 0.40%; monthly compounding; 3% inflation; 10 yrs
Output:: Total balance ≈ $22,400; total deposited = $22,000; total interest ≈ $400; real value ≈ $16,670; real premium ≈ −24%

A 0.40% APY at 3% inflation loses about 24% of purchasing power over a decade despite the nominal balance growing — a textbook example of why HYSAs matter.

When to use this vs other tools

This calculator handles deposit-account savings projections. For investment portfolios, goal-back-solving, or borrowing questions, the sibling tools below are more specialized.

Compound Interest Calculator
You are projecting investment returns (stocks, bonds, index funds) rather than a bank deposit — uses nominal returns and longer horizons.
Savings Goal Calculator
You have a target dollar amount and need to back-calculate the monthly deposit needed to hit it on a given timeline.
Inflation Calculator
You want to see the historical CPI-based purchasing power of a dollar amount between any two years.
Emergency Fund Calculator
You want to size 3-6 months of expenses as a target HYSA balance rather than project growth.

Authority note

CFPB / FDIC

Regulation DD (12 CFR Part 1030) — Truth in Savings Act; FDIC Deposit Insurance ($250,000 per depositor per insured bank)

Truth in Savings (Reg DD) standardized APY disclosure across all US deposit accounts in 1991, making bank-to-bank comparison possible — the calculator follows the same APY convention. FDIC insurance protects depositors up to $250k per ownership category at each insured institution; credit-union accounts have parallel NCUA coverage at the same limit.

Limitations

APY is not guaranteed beyond the disclosure period — variable-rate HYSAs typically reset monthly or quarterly as the Federal Reserve adjusts the federal funds rate.
CD APYs are locked for the term but early-withdrawal penalties can convert the apparent yield into a loss; this calculator assumes you hold for the full period without withdrawal.
Inflation projection uses a single constant rate. Real-world inflation is volatile (US CPI ranged from −0.4% in 2009 to +8.0% in 2022); a single rate is a planning aid, not a forecast.
The calculator does not subtract federal/state income tax on interest. Interest earned on a taxable savings account is taxed as ordinary income in the year credited; for a more accurate real after-tax growth figure, multiply the interest by (1 − marginal tax rate).
Above $250,000 per depositor per bank, balances are uninsured by FDIC. Multi-bank splits, IntraFi-network sweep accounts, and joint or revocable-trust ownership categories provide higher effective coverage.
Foreign-bank accounts and crypto-yield products are outside FDIC scope entirely and carry institutional risk this calculator does not model.

Savings projections are illustrative. This calculator does not provide financial, banking, or tax advice. Bank-disclosed APYs and FDIC coverage rules are the authoritative figures; consult an FDIC EDIE estimator or your bank's disclosures for any deposit decision above $250,000.

Frequently asked

APY (Annual Percentage Yield) includes the effect of compounding within the year; the "interest rate" is the nominal rate before compounding. For a 4.40% nominal rate compounded daily, APY = (1 + 0.044/365)^365 − 1 = 4.50%. The Truth in Savings Act (Regulation DD, 12 CFR 1030) requires US banks to disclose APY on every advertisement, account opening, and periodic statement so consumers can compare apples-to-apples across compounding methods.