Patent Term Calculator
Estimate the remaining enforceable term of a US utility patent, accounting for Patent Term Adjustment (PTA) and Patent Term Extension (PTE).
Formula
Base Expiry = Filing Date + 20 years (35 U.S.C. § 154(a)(2))
PTA-Adjusted Expiry = Base Expiry + PTA Days (35 U.S.C. § 154(b))
Final Expiry = PTA-Adjusted Expiry + PTE Days (35 U.S.C. § 156), subject to cap
PTE Cap: Final Expiry ≤ Grant Date + 14 years (35 U.S.C. § 156(c)(3))
Remaining Term = Final Expiry − Reference Date
Assumptions & References
- Applies to US utility patents filed on or after June 8, 1995 (GATT/TRIPS implementation).
- 20-year base term runs from the earliest effective US filing date (35 U.S.C. § 154(a)(2)).
- Patent Term Adjustment (PTA) compensates for USPTO delays during prosecution (35 U.S.C. § 154(b)). The exact PTA is printed on the grant certificate.
- Patent Term Extension (PTE) compensates for regulatory review delays (e.g., FDA approval) under 35 U.S.C. § 156. Maximum PTE is 5 years (1,825 days), and the remaining term after extension cannot exceed 14 years from grant.
- Maintenance fees must be paid at 3.5, 7.5, and 11.5 years post-grant to keep the patent in force (37 C.F.R. § 1.362). This calculator does not account for lapsed maintenance fees.
- Terminal disclaimers, reexamination, or inter partes review outcomes may further affect patent term and are not modeled here.
- Design patents have a 15-year term from grant (35 U.S.C. § 173) and are not covered by this calculator.
- References: 35 U.S.C. §§ 154, 156; 37 C.F.R. §§ 1.362, 1.701–1.705; USPTO Patent Term Calculator guidance.