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font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
max-width: 800px;
margin: 20px auto;
padding: 30px;
border: 1px solid #e1e1e1;
border-radius: 12px;
background-color: #ffffff;
box-shadow: 0 4px 15px rgba(0,0,0,0.05);
}
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margin-top: 0;
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.full-width {
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}
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color: white;
padding: 15px 25px;
border: none;
border-radius: 6px;
cursor: pointer;
font-size: 18px;
font-weight: bold;
width: 100%;
transition: background 0.3s;
}
.calc-btn:hover {
background-color: #2980b9;
}
.result-box {
margin-top: 25px;
padding: 20px;
background-color: #f8f9fa;
border-left: 5px solid #27ae60;
border-radius: 4px;
}
.result-box h3 {
margin: 0 0 10px 0;
color: #27ae60;
}
#expirationDateDisplay {
font-size: 24px;
font-weight: bold;
color: #2c3e50;
}
.info-text {
font-size: 13px;
color: #7f8c8d;
margin-top: 5px;
}
@media (max-width: 600px) {
.input-grid { grid-template-columns: 1fr; }
.full-width { grid-column: span 1; }
}
How to Determine When a Patent Expires
Calculating the exact expiration date of a patent is critical for inventors, businesses, and legal professionals. In the United States, the term of a patent depends heavily on its type and when the application was filed. This calculator helps estimate the end-of-term date based on current USPTO (United States Patent and Trademark Office) regulations.
Standard Patent Terms in the United States
| Patent Type |
Term Length |
Start Point |
| Utility Patent |
20 Years |
Effective Filing Date |
| Design Patent |
15 Years |
Date of Grant (Issue Date) |
| Plant Patent |
20 Years |
Effective Filing Date |
Key Factors That Modify Expiration
1. Patent Term Adjustment (PTA)
The USPTO sometimes takes longer than statutory deadlines to process an application. To compensate the inventor for this lost time, the office may grant "PTA days," which are added directly to the end of the patent's life.
2. Patent Term Extension (PTE)
Common in the pharmaceutical and biotech industries, PTE compensates for time lost during the regulatory review process (such as waiting for FDA approval). These extensions are crucial for drugs that spend years in clinical trials before hitting the market.
3. Terminal Disclaimers
If a patent is very similar to another patent owned by the same entity, the USPTO may require a terminal disclaimer. This means the newer patent will expire on the same day as the earlier patent, regardless of its own filing date. Our calculator provides a base estimate, but always check the patent's "Face Page" for disclaimer notifications.
4. Maintenance Fees
Utility patents require the payment of maintenance fees at 3.5, 7.5, and 11.5 years after issuance. If these fees are not paid, the patent will lapse early, and the invention will enter the public domain.
Example Calculation
Suppose you have a Utility Patent with an effective filing date of June 1, 2010. The standard 20-year term would end on June 1, 2030. However, if the USPTO granted 450 days of PTA due to administrative delays, the new expiration date would be August 25, 2031.
Important Disclaimer: This calculator provides an estimate for educational purposes. Patent law is subject to complex rules including the "Pre-GATT" rules for patents filed before June 8, 1995. For legal certainty, consult with a qualified patent attorney.
function toggleInputs() {
var type = document.getElementById('patentType').value;
var filingGroup = document.getElementById('filingDateGroup');
var grantGroup = document.getElementById('grantDateGroup');
if (type === 'design') {
filingGroup.style.display = 'none';
grantGroup.style.display = 'flex';
} else {
filingGroup.style.display = 'flex';
grantGroup.style.display = 'none';
}
}
function calculateExpiration() {
var type = document.getElementById('patentType').value;
var filingDateInput = document.getElementById('filingDate').value;
var grantDateInput = document.getElementById('grantDate').value;
var pta = parseInt(document.getElementById('ptaDays').value) || 0;
var pte = parseInt(document.getElementById('pteDays').value) || 0;
var baseDate;
var termYears;
var summaryText = "";
if (type === 'design') {
if (!grantDateInput) {
alert("Please select the Grant (Issue) Date.");
return;
}
baseDate = new Date(grantDateInput);
termYears = 15;
summaryText = "Design patents filed after May 2015 last 15 years from grant.";
} else {
if (!filingDateInput) {
alert("Please select the Effective Filing Date.");
return;
}
baseDate = new Date(filingDateInput);
termYears = 20;
summaryText = (type === 'utility' ? "Utility" : "Plant") + " patents last 20 years from the effective filing date.";
}
// Calculation logic
var expirationDate = new Date(baseDate);
expirationDate.setFullYear(expirationDate.getFullYear() + termYears);
// Add PTA and PTE days
var totalExtraDays = pta + pte;
if (totalExtraDays > 0) {
expirationDate.setDate(expirationDate.getDate() + totalExtraDays);
summaryText += " Includes " + totalExtraDays + " days of extensions (PTA/PTE).";
}
// Format Date
var options = { year: 'numeric', month: 'long', day: 'numeric' };
var formattedDate = expirationDate.toLocaleDateString(undefined, options);
// Display results
document.getElementById('expirationDateDisplay').innerText = formattedDate;
document.getElementById('logicSummary').innerText = summaryText;
document.getElementById('resultArea').style.display = 'block';
// Scroll to result
document.getElementById('resultArea').scrollIntoView({ behavior: 'smooth', block: 'nearest' });
}