How long does a patent last?

A standard utility patent lasts 20 years from its earliest non-provisional filing date, provided maintenance or renewal fees are paid. The date can be extended by patent term adjustment or extension, or shortened by a terminal disclaimer.

Does the 20 years run from filing or grant?

From filing, not grant. The 20-year term is measured from the earliest non-provisional (or PCT international) filing date, so a patent that took years to grant has a shorter enforceable life.

Guide · Patent term

When does a patent expire? How to calculate the real date

Last updated September 2026 · ~5 min read

"Twenty years" is the headline answer — but the real expiry date of a patent can be earlier or later, and it's the real date that decides when competitors are free to move. Here's how patent term actually works and how to find the date that matters.

The basic rule: 20 years from filing

A standard utility patent lasts 20 years from its earliest non-provisional filing date — not from the grant date. That's a crucial distinction: if an application took four years to grant, the patent still expires 20 years after filing, so its enforceable life is effectively 16 years.

A few nuances:

Provisional applications don't count toward the 20 years. A provisional sets your priority date, but the term runs from the later non-provisional filing.
PCT / national-phase cases run from the international (PCT) filing date.
Continuations and divisionals generally expire 20 years from the earliest application they claim priority to — so a continuation filed years later can have very little term left.
Design patents are different — in the US they run 15 years from grant, with no maintenance fees.

What can move the date

Extensions (later expiry)

Patent Term Adjustment (PTA) adds days back to a US patent's term to compensate for delays caused by the USPTO during examination. Patent Term Extension (PTE) can add time for products that needed regulatory approval (common in pharmaceuticals). Both push the expiry date later than the plain 20-year calculation.

Terminal disclaimers (earlier expiry)

A terminal disclaimer ties a patent's expiry to that of an earlier related patent (usually to overcome a double-patenting rejection). If a patent has one, it can expire earlier than 20 years from its own filing date.

Unpaid fees (early death)

Even a patent nowhere near its 20-year term will expire early if a maintenance fee (US) or renewal fee (Europe) goes unpaid. In practice this is the most common reason a patent ends before its natural expiry.

Estimate a patent's expiry free

Enter any US or European patent number and get an estimated expiry date and how much term is left — calculated from the filing date. No signup.

Patent expiry calculator → Full portfolio audit

How to find the real expiry date

Start with the earliest filing date and add 20 years for the baseline.
Check for PTA/PTE on the front page of the granted patent — it may add days or years.
Check for a terminal disclaimer — it may pull the date earlier.
Confirm fees are current — an unpaid maintenance or renewal fee ends the patent regardless of term.

A quick estimate (20 years from filing) is fine for planning; for a date you'll rely on, verify the adjustments against the official record. Our expiry calculator gives you the estimate instantly, and IP Axix keeps the whole portfolio's terms and fee deadlines in one place so nothing expires by accident.

Related free tools

Patent expiry calculator — estimated expiry and remaining term.
Maintenance-fee estimator — the fees that keep a US patent alive.
Full portfolio audit — every deadline plus a health score.

General information only, not legal advice. Patent term depends on the specific facts of each case; always verify PTA/PTE, terminal disclaimers and fee status against the official record and confirm critical dates with your patent attorney.