Savings Bond Calculator
This calculator estimates the current redemption value and accrued interest for U.S. savings bonds based on user-supplied dates, purchase amount, and an annual rate. It provides multiple workflows: Series I (use composite annual rate) and Series EE (use stated annual yield or an optional guaranteed doubling rule where applicable).
Results are estimates produced by compounding the supplied annual rate monthly and do not automatically fetch official published rates. Use official published rates and exact redemption schedules when making legal or tax decisions.
Estimate value using a user-supplied annual composite rate (enter the current published composite annual rate as a percent). This method compounds monthly.
Inputs
Advanced inputs
EE bond special options
Results
Estimated current value
$64.79
Accrued interest
$14.79
Months since issue
311
| Output | Value | Unit |
|---|---|---|
| Estimated current value | $64.79 | USD |
| Accrued interest | $14.79 | USD |
| Months since issue | 311 | months |
Visualization
Methodology
The tool treats the provided annual rate as an effective nominal annual rate and converts it to a monthly rate for compounding: monthly_rate = annual_rate / 12. The valuation period is the month difference between issue and redemption dates. The calculator compounds monthly for the estimated future value.
For Series I, users should supply the composite annual rate (published as a percentage) if they want an estimate that reflects the published composite. For Series EE, users may supply the bond's stated annual yield or enable the guaranteed doubling option (where the bond's program rule guarantees a specific outcome).
All model decisions, rounding behavior, and inputs should be validated against official documentation before use in compliance reporting or tax filings. This tool follows quality and accuracy practices inspired by ISO 9001 (quality management), NIST guidance for data integrity, and general numerical precision recommendations from IEEE.
Key takeaways
This calculator is a practical estimator for bond value and accrued interest using user-supplied rates and dates. It supports multiple workflows and provides transparent assumptions.
For legally binding valuations or tax reporting, always verify with official documentation and published rates.
Further resources
External guidance
Expert Q&A
Does this calculator use official published Treasury rates automatically?
No. The calculator requires you to enter an annual rate or composite rate. It does not fetch official published rates. Always cross-check results with official rate publications for precise redemptions.
Why does the tool compound monthly?
Monthly compounding is used here as a consistent, conservative estimate for accrual over fractions of a year. Actual accrual rules for specific bond issues may use semi-annual or other accrual conventions; consult official bond documentation for exact treatments.
How accurate are the results?
Results are estimates intended for planning. They follow numerical best practices but do not replace official redemption calculations. See the accuracy & compliance note below for standards and limits.
What should I enter for the annual rate field?
Enter the bond's annual yield or, for Series I, the composite annual rate (expressed as a percentage). If unsure, use the official published composite or yield for the relevant issue date.
Sources & citations
- National Institute of Standards and Technology (NIST) - Data Integrity & Quality — https://www.nist.gov
- International Organization for Standardization (ISO) 9001 — Quality management principles — https://www.iso.org/iso-9001-quality-management.html
- IEEE — Numerical and computational standards and recommendations — https://standards.ieee.org
- Occupational Safety and Health Administration (OSHA) — Technical compliance guidance — https://www.osha.gov