CD Calculator

Before you calculate

Use this calculator when the core question is a fixed-term deposit with no additional deposits or withdrawals before maturity. Use the savings calculator when recurring deposits or contribution increases matter, the interest calculator when timing and inflation inputs matter, and the interest-rate calculator when you need to solve for a rate instead of entering one.

Formula summary

The calculator converts the entered annual interest rate into an effective monthly rate from the selected compounding option. Annual compounding uses the twelfth root of the annual growth factor; continuous compounding uses e^(rate / 12) - 1. It rounds years * 12 + months to whole term months, grows the initial deposit to gross maturity value, calculates total gross interest, applies the marginal tax-rate assumption to gross interest after maturity, then reports after-tax balance, effective annual yield, first-month interest, and first-year interest.

Worked example

Example: $10,000 at 5 percent annually for 3 years

With the default inputs, a $10,000 initial deposit, 5 percent annual rate, annual compounding, 3 years, 0 extra months, and 0 percent tax produce a gross maturity balance of $11,576.25. Total gross interest is $1,576.25, estimated tax due is $0.00, effective annual yield is 5.00 percent, first-month interest is $40.74, and first-year interest is $500.00. A taxed monthly example with $25,000, 4.8 percent monthly compounding, 2 years and 6 months, and a 24 percent tax-rate assumption produces $28,180.68 gross maturity, $3,180.68 gross interest, $763.36 estimated tax due, and $27,417.31 after-tax end balance.

The result explains one fixed-rate maturity model from the inputs. It is not a bank quote, official APY disclosure, tax calculation, deposit-insurance determination, provider comparison, or recommendation about a CD.

Assumptions

• The initial deposit stays in the CD for the full entered term, and the entered rate and compounding choice stay fixed for the whole estimate.
• The tax-rate input is a simple user-entered assumption applied to total gross interest after maturity. The calculator does not reduce reinvested interest each period and does not calculate official tax reporting, withholding, allowances, account wrappers, original issue discount, state tax, or local rules.
• The calculator does not pull live APY, AER, provider quotes, renewal terms, promotional terms, account fees, early-withdrawal penalties, call features, brokered-CD rules, minimum balances, deposit-insurance coverage, inflation, or personal circumstances. Results remain educational estimates rather than financial, tax, legal, lending, investment, provider, or regulated advice.

Common mistakes to avoid

• Treating the entered interest rate as an advertised APY or provider quote. The calculator only uses the rate you type and shows an effective annual yield from that internal monthly-rate conversion.
• Reading Estimated tax due as an official tax bill. It is a flat percentage of gross interest in this model and may differ from real account, reporting, or jurisdiction-specific treatment.
• Ignoring term and product rules. Early-withdrawal penalties, renewal defaults, call features, brokered-CD terms, fees, and deposit-insurance limits can change the real-world result but are not calculator inputs.

Methodology and sources

This calculator is an original implementation based on documented formulas, app-specific assumptions, deterministic fixtures, edge cases, rounding policy tests, and internal validation. It is not copied from a single source.

Outputs are checked with deterministic fixtures, edge cases, rounding policy tests, and internal independent comparator checks where overlapping outputs are available. The result remains an educational estimate, not a quote, approval, tax answer, or personalised advice.

Formula version 2026.05.22-generic-cd-maturity. The version marks the calculation logic and validation fixture set used for this estimate.

• CFPB Regulation DD Appendix A should be used before copy discusses US annual percentage yield calculations, advertised APY terminology, time-account disclosure assumptions, bonuses, stepped rates, tiered rates, or product-specific account-yield claims.
• IRS Topic 403 and relevant state or local tax-authority materials should be used before copy discusses US taxable interest, certificate-of-deposit tax reporting, withholding, original issue discount, tax-exempt interest, state tax, or personal tax outcomes.
• FDIC, NCUA, FSCS, and relevant local deposit-protection sources should be used before copy discusses insured-bank or credit-union CD coverage, protected-balance limits, ownership categories, bank eligibility, failed-bank treatment, or jurisdiction-specific deposit protection.
• SEC Investor.gov, FINRA, bank/provider disclosures, deposit-broker materials, and relevant local regulators should be used before copy discusses brokered CDs, callable CDs, early-withdrawal penalties, renewal defaults, minimum balances, account fees, promotional rates, liquidity, issuer checks, product risks, or provider-specific terms.

Estimate only

The result is educational and is not financial, tax, legal, lending, investment, or regulated advice. Real provider terms, fees, rates, taxes, and personal circumstances can change the final answer.

Formula and help: read the full cd calculator methodology notes.

Related reading

• How Calcs.finance validates calculator formulas
• Estimate limitations and not-advice disclaimer

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