body {
font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
line-height: 1.6;
color: #333;
max-width: 800px;
margin: 0 auto;
padding: 20px;
}
.calculator-container {
background-color: #f8f9fa;
border: 1px solid #e9ecef;
border-radius: 8px;
padding: 30px;
margin-bottom: 40px;
box-shadow: 0 4px 6px rgba(0,0,0,0.05);
}
.calculator-title {
text-align: center;
color: #fc4c02; /* Strava Orange */
margin-bottom: 25px;
font-size: 24px;
font-weight: bold;
}
.input-group {
margin-bottom: 20px;
}
.input-group label {
display: block;
margin-bottom: 8px;
font-weight: 600;
color: #242428;
}
.input-group input, .input-group select {
width: 100%;
padding: 12px;
border: 1px solid #ccc;
border-radius: 4px;
font-size: 16px;
box-sizing: border-box;
}
.calculate-btn {
width: 100%;
background-color: #fc4c02; /* Strava Orange */
color: white;
border: none;
padding: 15px;
font-size: 18px;
font-weight: bold;
border-radius: 4px;
cursor: pointer;
transition: background-color 0.2s;
}
.calculate-btn:hover {
background-color: #d63d00;
}
.results-area {
margin-top: 25px;
background-color: #fff;
border: 1px solid #ddd;
border-radius: 4px;
padding: 20px;
display: none;
}
.result-row {
display: flex;
justify-content: space-between;
align-items: center;
padding: 10px 0;
border-bottom: 1px solid #eee;
}
.result-row:last-child {
border-bottom: none;
}
.result-label {
font-weight: 600;
color: #555;
}
.result-value {
font-weight: bold;
font-size: 18px;
color: #242428;
}
.primary-result {
text-align: center;
margin-bottom: 20px;
padding-bottom: 20px;
border-bottom: 2px solid #fc4c02;
}
.primary-result .val {
font-size: 42px;
font-weight: 800;
color: #fc4c02;
line-height: 1;
}
.primary-result .sub {
font-size: 14px;
color: #666;
margin-top: 5px;
}
.article-content h2 {
color: #2c3e50;
margin-top: 40px;
}
.article-content h3 {
color: #34495e;
margin-top: 30px;
}
.article-content ul {
margin-bottom: 20px;
}
.article-content li {
margin-bottom: 10px;
}
.info-box {
background-color: #e8f4f8;
border-left: 4px solid #3498db;
padding: 15px;
margin: 20px 0;
}
function calculateStravaHR() {
// Get Inputs
var ageInput = document.getElementById('athleteAge');
var methodInput = document.getElementById('calculationMethod');
var resultsDiv = document.getElementById('hrResults');
var mainDisplay = document.getElementById('mainHrDisplay');
var age = parseInt(ageInput.value);
var method = methodInput.value;
// Validation
if (isNaN(age) || age 120) {
alert("Please enter a valid age between 1 and 120.");
return;
}
// Logic based on Strava's common methodologies
var maxHR = 0;
if (method === 'standard') {
// Fox Formula: 220 – Age
maxHR = 220 – age;
} else if (method === 'tanaka') {
// Tanaka Formula: 208 – (0.7 x Age)
maxHR = 208 – (0.7 * age);
} else if (method === 'gulati') {
// Gulati Formula: 206 – (0.88 x Age)
maxHR = 206 – (0.88 * age);
}
// Round to nearest whole number
maxHR = Math.round(maxHR);
// Calculate Zones (Standard 5-Zone Model used by Strava)
// Zone 1: 50-60% (Recovery) – Actually Strava often starts Z1 at 0 or very low, but functionally training starts here.
// For display we will use standard percentage breakdowns often mapped in Strava.
// Strava Default:
// Z1: 0-65% (Active Recovery)
// Z2: 65-80% (Endurance) – Note: Strava's default zones are quite broad.
// However, standard Coggan/Friel or simplified 5-zone often used:
// Z1: 50-60%
// Z2: 60-70%
// Z3: 70-80%
// Z4: 80-90%
// Z5: 90-100%
// Let's use the standard percentage splits common in cycling/running setup within Strava manual entry.
var z1Limit = Math.round(maxHR * 0.60);
var z2Limit = Math.round(maxHR * 0.70);
var z3Limit = Math.round(maxHR * 0.80);
var z4Limit = Math.round(maxHR * 0.90);
// Update UI
resultsDiv.style.display = "block";
mainDisplay.innerText = maxHR;
document.getElementById('zone1').innerText = " " + z4Limit;
}
How Does Strava Calculate Max Heart Rate?
Understanding your heart rate zones is critical for effective training, whether you are a cyclist, runner, or triathlete. Strava, one of the world's most popular fitness tracking apps, relies heavily on your Maximum Heart Rate (Max HR) to define these zones. But how exactly does Strava come up with this number if you don't enter it manually?
Quick Answer: By default, Strava calculates your Max Heart Rate using the standard formula: 220 minus your age. However, users can (and should) customize this for better accuracy.
The Default Formula: 220 – Age
When you first create a Strava account and enter your date of birth, the platform automatically estimates your Max HR using the Fox formula:
Max HR = 220 - Age
While this formula is widely known and simple to use, it is a generalized statistical average. For many athletes, specifically those who have been training for years, this formula can be notoriously inaccurate. It tends to underestimate Max HR for older athletes and overestimate it for younger ones.
Alternative Formulas Used in Fitness
If you find that your perceived exertion doesn't match the zones Strava has assigned you, you might be calculating your Max HR incorrectly. The calculator above allows you to test two popular alternatives that many athletes manually enter into Strava:
1. The Tanaka Formula
Max HR = 208 - (0.7 × Age)
The Tanaka equation is generally considered more accurate for a wider range of the healthy adult population. It flattens the curve, meaning it often yields a slightly higher Max HR for older adults compared to the Fox formula.
2. The Gulati Formula (For Women)
Max HR = 206 - (0.88 × Age)
Research suggests that the standard male-centric formulas often overestimate peak heart rate for women. The Gulati formula is specifically derived from data on women and may provide a better baseline for female athletes setting up their Strava zones.
How to Update Your Max Heart Rate in Strava
Since the default calculation is merely an estimate, Strava encourages athletes to input their actual physiological data if known. To update this manually:
- Web: Go to Settings > My Performance > Heart Rate Zones. Select "Custom" and input your specific Max HR.
- Mobile App: Navigate to Profile > Settings > Performance Potential > Heart Rate Zones.
Determining Your True Max Heart Rate
The most accurate way to determine your Max HR is not through a calculator, but through a field test. A common field test involves:
- A thorough 15-minute warm-up.
- Running or cycling at a high intensity for 3 minutes.
- Resting for 2 minutes.
- Running or cycling at maximum effort for another 3 minutes.
The highest heart rate value recorded during the final interval is usually your Max HR. Once you have this number, input it into Strava manually to ensure your relative effort scores and training zones (Endurance, Tempo, Threshold) are aligned with your actual physiology.
Why Does Accuracy Matter?
Strava uses your heart rate data to calculate Relative Effort (formerly Suffer Score) and Fitness & Freshness trends. If your Max HR is set too high, Strava will think you are working less hard than you actually are. Conversely, if it is set too low, your training load will appear artificially inflated. Ensuring this number is accurate is the first step toward data-driven training success.