Years to Centuries

How Long a Right Lasts, Measured Against a Hundred Years

Intellectual property is the one area of law that routinely writes durations nobody involved will live through. A patent expires in twenty years and its holder usually sees the end of it. A copyright runs for the author's life and seventy years after, which for a novelist who published at twenty-five and died at eighty means the work is locked up for a hundred and twenty-five years — longer than the century that people reach for when they want to say "a very long time".

Putting these terms on a century scale is what makes the differences legible. A twenty-year patent and a life-plus-seventy copyright are both called protection, but one is a fifth of a century and the other is more than a whole one. Anyone building a rights register, clearing archive material or deciding whether to license or wait is really deciding between those two orders of magnitude.

Conversion factor: 1 c = 100 yr exactly, so divide by a hundred. A 20-year utility patent is 0.2 c; the 95-year term for a US work made for hire is 0.95 c; and life-plus-70 for an author who created at 25 and died at 80 comes to 125 yr, or 1.25 c.

What the Century Scale Reveals

Only copyright reaches century scale

Every other right sits well below 0.5 c. Copyright is the outlier, running from about 0.7 c for a sound recording to 1.2 c or more once an author's lifetime is added to the statutory tail.

A patent is a fifth of a century, on paper

The 20 years run from the filing date, not the grant, so the years spent in examination are inside the term. Effective exclusivity is often several years shorter than the 0.2 c the statute names.

One right has no term at all

A registered trade mark is granted for 10 years, or 0.1 c, and can be renewed indefinitely while it is still used. Converting it to centuries is meaningless: the only limit is abandonment.

Terms end on a date, not after a duration

Copyright expires at the end of the calendar year in which the count runs out, so the arithmetic here gives a length rather than a moment. The converter's year is a fixed 365.2425 days and knows nothing about 31 December.

Putting a Statutory Term Onto the Century Scale

The conversion itself is trivial; getting the right number of years to feed it is where the care goes.

Assemble the full term before converting

For copyright that means the author's remaining lifetime plus the statutory tail; for a pharmaceutical patent it means 20 years plus any supplementary protection certificate. Convert the total, not the headline figure.

Enter the year count

Type 125 and 1.25 c lands beside it; 20 gives 0.2 c; 95 gives 0.95 c. Both fields accept a comma or a dot as the decimal mark, so a figure pasted from a European document needs no editing.

Reverse it when a source talks in centuries

Swap (↔) puts centuries first, so a policy paper complaining about "protection lasting well over a century" resolves to the 100-plus years you can then test against a real publication date.

Anchor the term to a date

Copy the bare number into a rights register and add it to the anchor date — death, publication or filing, depending on the right — then round the result to the end of that calendar year where the law requires it.

A term is not an expiry date: each right counts from a different anchor. Patents run from filing, works made for hire from first publication, author copyright from the author's death, and most copyright terms then extend to 31 December of the final year. Two works with identical 0.95 c terms can fall into the public domain years apart. This page is orientation, not legal advice.

Protection Terms Across the Main Rights

Headline terms under US, UK and EU law, converted at 100 years to the century. Where a term depends on a lifetime, the example assumes an author who created the work at 25 and died at 80, giving 55 remaining years plus the statutory tail.

Right	Term in years	Term in centuries	Counted from
Supplementary protection certificate (EU pharma)	up to 5 yr	0.05 c	Added at the end of the base patent term
Registered trade mark, one term	10 yr	0.1 c	Registration; renewable indefinitely
US design patent	15 yr	0.15 c	Grant, with no maintenance fees
EU database right	15 yr	0.15 c	Completion, renewable on substantial investment
Utility patent (US, EU, UK)	20 yr	0.2 c	Filing date, subject to renewal fees
Sound recording (UK and EU)	70 yr	0.7 c	Publication or communication to the public
US work made for hire, published	95 yr	0.95 c	First publication
US work made for hire, unpublished	120 yr	1.2 c	Creation, whichever expires first
Author copyright, Berne minimum (life + 50)	105 yr	1.05 c	Creation, in the worked example above
Author copyright, US/UK/EU standard (life + 70)	125 yr	1.25 c	Creation, in the worked example above

Read the third column downwards and the shape of the bargain appears. Rights over inventions, which are expensive to produce and cheap to copy, are handed out in slices of a fifth of a century and paid for annually. Rights over expression run five to six times longer and cost nothing to maintain. Whether that gap is justified is an argument that has run since the 1998 US term extension; what is not arguable is that the two systems are not operating on the same clock, and a rights table that lists them in the same column of years hides it.

Useful When Clearing Rights

Terms convert as you read them off the statute

Checking a list of rights takes one keystroke per figure, with the century equivalent appearing beside the year count rather than after a button press.

Century claims can be tested backwards

The right-hand field takes input too, so "more than a century of protection" can be entered as 1.25 and checked against the 125 years it actually asserts.

Small terms keep their detail

A five-year extension shows as 0.05 c rather than collapsing to zero, which matters when the question is what a supplementary certificate is worth.

Numbers ready for a rights register

Copy hands over the digits with no unit, so a term can be added to an anchor date in a spreadsheet without being cleaned up first.

Questions About Terms, Expiry and the Public Domain

When exactly does a life-plus-70 copyright run out?

Seventy years are counted from the author's death, and in the US, UK and EU the term then runs to 31 December of that seventieth year. An author who died in 1955 is out of copyright from 1 January 2026 in those jurisdictions. Two complications bite often: joint works are measured from the death of the last surviving author, which can add decades, and the term applies to the work rather than to a particular edition, so a modern translation or critical apparatus carries its own separate copyright. Where the author's death date is unknown, most systems fall back on a fixed period from creation or publication instead.

Does a patent really give a full twenty years of exclusivity?

Rarely. The 0.2 c starts at the filing date, and examination commonly takes two to five years, during which the applicant has no enforceable granted right. For medicines the gap is worse, because clinical trials and regulatory approval eat further into the term — which is exactly why supplementary protection certificates and patent term extensions exist, adding up to five years, or 0.05 c, to compensate. Renewal fees also have to be paid periodically and rise steeply, so a large share of patents are abandoned well before the twenty years are up because the remaining term is not worth the cost.

Which works enter the public domain each January?

In the United States the published-works cohort moves forward by one year every 1 January, because those older works run for 95 years, or 0.95 c, from first publication. Works first published in 1930 lost protection at the end of 2025 and became free to use on 1 January 2026; the 1931 cohort follows a year later. The rolling pattern only restarted in 2019, after a twenty-year freeze. Elsewhere the calendar is driven by author deaths rather than publication dates, so the same work can be public domain in one country and protected in another — check the jurisdiction you intend to publish in, not the one you are sitting in.

Can a term be lengthened after a work is already protected?

It has happened, most visibly in 1998 when US legislation added 20 years — 0.2 c — to existing terms and stopped anything new entering the public domain until 2019. The EU had moved to life plus 70 a few years earlier, which in some member states revived rights in works that had already lapsed. The practical lesson for anyone keeping a rights register is that an expiry date is a calculation under current law, not a fact, and long-dated entries should be recorded with the rule that produced them so they can be recomputed if the rule changes.

If almost nothing lasts a full century, why measure these terms in centuries at all?

For comparison rather than for daily use. Most terms convert to awkward fractions — 0.15, 0.2, 0.7 — and no lawyer drafts in them. What the century scale is good for is arguing about proportion: it shows at a glance that copyright over expression outlasts patent protection over invention by roughly six to one, and that a single copyright term can outrun the working life of every institution that might want to license the work. For anything operational, stay in years and dates, because that is the unit the statutes are written in and the unit an expiry calculation has to land on.