Orangetheory Fitness utilizes five color-coded heart rate zones to monitor intensity during a workout. By calculating your Maximum Heart Rate (MHR), you can target specific "Splat Points"—minutes spent in the Orange and Red zones—to trigger the Afterburn effect (EPOC).
Our calculator uses the Tanaka Formula (208 – 0.7 × Age), which is the standard algorithm used by most modern heart rate monitors to estimate maximum intensity for aerobic exercise.
What Do the Colors Mean?
Grey Zone (0-60%): This is your resting heart rate or very light activity, like walking to your station.
Blue Zone (61-70%): A warm-up pace. You are moving but not yet strained.
Green Zone (71-83%): The "Base Pace." You should be able to maintain this intensity for 20-30 minutes. It builds aerobic endurance.
Orange Zone (84-91%): The "Push Pace." This is where the magic happens. Spending 12 minutes or more here earns you Splat Points and boosts your metabolism for up to 36 hours.
Red Zone (92-100%): The "All Out" effort. This should only be maintained for short bursts, typically 30 to 60 seconds.
Example Calculation
If you are 40 years old, your estimated Max HR is 180 BPM (208 – 0.7 * 40). To reach the Orange Zone, you would need your heart rate to be between 151 BPM (84%) and 164 BPM (91%).
Why 12 Splat Points?
The goal of an Orangetheory class is to spend a combined 12 minutes or more in the Orange and Red zones. Science suggests this duration is the "sweet spot" to achieve Excess Post-exercise Oxygen Consumption (EPOC), which helps you burn calories long after you leave the studio.
function calculateOTFZones() {
var ageInput = document.getElementById("otfAge").value;
var age = parseFloat(ageInput);
if (!age || age 115) {
alert("Please enter a valid age.");
return;
}
// Tanaka Formula: 208 – (0.7 * age)
var maxHR = 208 – (0.7 * age);
maxHR = Math.round(maxHR);
// Calculate Zone Ranges
// Zone 1: 0-60%
var z1Min = 0;
var z1Max = Math.round(maxHR * 0.60);
// Zone 2: 61-70%
var z2Min = Math.round(maxHR * 0.61);
var z2Max = Math.round(maxHR * 0.70);
// Zone 3: 71-83%
var z3Min = Math.round(maxHR * 0.71);
var z3Max = Math.round(maxHR * 0.83);
// Zone 4: 84-91%
var z4Min = Math.round(maxHR * 0.84);
var z4Max = Math.round(maxHR * 0.91);
// Zone 5: 92-100%
var z5Min = Math.round(maxHR * 0.92);
var z5Max = maxHR;
// Display Results
document.getElementById("maxHRVal").innerText = maxHR;
document.getElementById("z1″).innerText = z1Min + " – " + z1Max + " BPM";
document.getElementById("z2″).innerText = z2Min + " – " + z2Max + " BPM";
document.getElementById("z3″).innerText = z3Min + " – " + z3Max + " BPM";
document.getElementById("z4″).innerText = z4Min + " – " + z4Max + " BPM";
document.getElementById("z5″).innerText = z5Min + " – " + z5Max + " BPM";
document.getElementById("otfResults").style.display = "block";
}