.ovulation-calc-container {
font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
max-width: 800px;
margin: 20px auto;
padding: 25px;
border: 1px solid #e1e1e1;
border-radius: 12px;
background-color: #ffffff;
box-shadow: 0 4px 15px rgba(0,0,0,0.05);
color: #333;
}
.ovulation-calc-header {
text-align: center;
margin-bottom: 30px;
}
.ovulation-calc-header h2 {
color: #d81b60;
margin-bottom: 10px;
}
.ovulation-calc-form {
display: grid;
grid-template-columns: 1fr 1fr;
gap: 20px;
margin-bottom: 30px;
}
.ovulation-calc-group {
display: flex;
flex-direction: column;
}
.ovulation-calc-group label {
font-weight: 600;
margin-bottom: 8px;
font-size: 14px;
color: #555;
}
.ovulation-calc-group input {
padding: 12px;
border: 1px solid #ccc;
border-radius: 6px;
font-size: 16px;
}
.ovulation-calc-btn {
grid-column: span 2;
background-color: #d81b60;
color: white;
border: none;
padding: 15px;
border-radius: 6px;
font-size: 18px;
font-weight: bold;
cursor: pointer;
transition: background 0.3s;
}
.ovulation-calc-btn:hover {
background-color: #ad1457;
}
.ovulation-calc-results {
display: none;
background-color: #fce4ec;
padding: 20px;
border-radius: 8px;
border-left: 5px solid #d81b60;
}
.result-item {
display: flex;
justify-content: space-between;
padding: 10px 0;
border-bottom: 1px solid rgba(216, 27, 96, 0.1);
}
.result-item:last-child {
border-bottom: none;
}
.result-label {
font-weight: 600;
}
.result-value {
font-weight: 700;
color: #d81b60;
}
.ovulation-content {
margin-top: 40px;
line-height: 1.6;
}
.ovulation-content h3 {
color: #d81b60;
margin-top: 25px;
}
@media (max-width: 600px) {
.ovulation-calc-form {
grid-template-columns: 1fr;
}
.ovulation-calc-btn {
grid-column: span 1;
}
}
Estimated Ovulation Day:
Fertile Window:
Next Period Due:
Estimated Due Date (If pregnant):
How Does the Ovulation Calculator Work?
The ovulation calculator uses the "Calendar Method" to estimate your fertile window. This method assumes that the luteal phase (the time between ovulation and your next period) is approximately 14 days long. By taking the length of your average menstrual cycle and subtracting 14 days from the projected start of your next period, we can estimate when an egg is likely to be released.
Understanding Your Fertile Window
While ovulation only lasts 12 to 24 hours, sperm can survive inside the female reproductive tract for up to 5 days. This means your "fertile window" is roughly 6 days long—the 5 days leading up to ovulation plus the day of ovulation itself. Having intercourse during this timeframe significantly increases the chances of conception.
Example Calculation
If your last period started on January 1st and you have a 28-day cycle:
- Next Period: January 29th
- Ovulation Day: January 15th (29 minus 14)
- Fertile Window: January 10th to January 15th
Signs of Ovulation
To confirm the results of this calculator, look for physical signs of ovulation, including:
- Cervical Mucus: Becomes clear, stretchy, and similar to raw egg whites.
- Basal Body Temperature: A slight increase in resting temperature (measurable with a sensitive thermometer).
- LH Surge: Detectable with over-the-counter ovulation predictor kits (OPKs).
- Mild Cramping: Some women experience "Mittelschmerz," a one-sided pelvic pain during ovulation.
function calculateOvulation() {
var lastDateInput = document.getElementById("lastPeriodDate").value;
var cycleLength = parseInt(document.getElementById("cycleLength").value);
if (!lastDateInput) {
alert("Please select the first day of your last period.");
return;
}
if (isNaN(cycleLength) || cycleLength 50) {
alert("Please enter a valid cycle length (usually between 20 and 45 days).");
return;
}
var lastDate = new Date(lastDateInput);
// 1. Next Period Calculation
var nextPeriodDate = new Date(lastDate);
nextPeriodDate.setDate(lastDate.getDate() + cycleLength);
// 2. Ovulation Day (Usually 14 days before next period)
var ovulationDate = new Date(nextPeriodDate);
ovulationDate.setDate(nextPeriodDate.getDate() – 14);
// 3. Fertile Window (5 days before ovulation + ovulation day)
var fertileStart = new Date(ovulationDate);
fertileStart.setDate(ovulationDate.getDate() – 5);
// 4. Due Date (Last Period + 280 days)
var dueDate = new Date(lastDate);
dueDate.setDate(lastDate.getDate() + 280);
// Format Options
var options = { month: 'long', day: 'numeric', year: 'numeric' };
// Display Results
document.getElementById("ovulationDay").innerText = ovulationDate.toLocaleDateString(undefined, options);
document.getElementById("fertileWindow").innerText = fertileStart.toLocaleDateString(undefined, options) + " – " + ovulationDate.toLocaleDateString(undefined, options);
document.getElementById("nextPeriod").innerText = nextPeriodDate.toLocaleDateString(undefined, options);
document.getElementById("dueDate").innerText = dueDate.toLocaleDateString(undefined, options);
document.getElementById("results").style.display = "block";
// Smooth scroll to results
document.getElementById("results").scrollIntoView({ behavior: 'smooth', block: 'nearest' });
}