Red Light Therapy Dosage Calculator

Red Light Therapy Dosage Calculator

1. Calculate Energy Delivered (Joules)

Use this to find out how much energy your current session is providing.

2. Calculate Required Time

Use this to find out how long you need to treat to hit a specific dosage target.

function calculateDosage() { var irr = parseFloat(document.getElementById('irradiance_1').value); var mins = parseFloat(document.getElementById('minutes_1').value); var resultDiv = document.getElementById('dosage_result'); if (isNaN(irr) || isNaN(mins) || irr <= 0 || mins <= 0) { resultDiv.innerHTML = "Please enter valid positive numbers."; resultDiv.style.color = "red"; return; } // Formula: Joules/cm² = (mW/cm² * seconds) / 1000 var seconds = mins * 60; var dosage = (irr * seconds) / 1000; resultDiv.style.color = "#333"; resultDiv.innerHTML = "Total Dosage: " + dosage.toFixed(2) + " J/cm²"; } function calculateTime() { var irr = parseFloat(document.getElementById('irradiance_2').value); var target = parseFloat(document.getElementById('target_dosage').value); var resultDiv = document.getElementById('time_result'); if (isNaN(irr) || isNaN(target) || irr <= 0 || target <= 0) { resultDiv.innerHTML = "Please enter valid positive numbers."; resultDiv.style.color = "red"; return; } // Formula: Seconds = (Joules/cm² * 1000) / mW/cm² var totalSeconds = (target * 1000) / irr; var mins = Math.floor(totalSeconds / 60); var secs = Math.round(totalSeconds % 60); resultDiv.style.color = "#333"; resultDiv.innerHTML = "Required Time: " + mins + "m " + secs + "s"; }

Understanding Red Light Therapy (RLT) Dosage

In photobiomodulation (Red Light Therapy), the "dosage" is the most critical factor for success. Getting the right amount of light energy to the target tissue is what triggers cellular benefits like increased ATP production and reduced inflammation. This energy is measured in Joules per square centimeter (J/cm²).

The Core Variables

• Irradiance (mW/cm²): This is the power density of the light. It represents how many photons are hitting a specific area of your skin every second. This value changes based on how far you stand from the device.
• Time (Minutes/Seconds): The duration of the exposure.
• Dosage (J/cm²): The total cumulative energy delivered.

The Dosage Formula

The math behind red light therapy is straightforward but essential to get right. To calculate the energy delivered, we use the following physics formula:

Dosage (J/cm²) = [Irradiance (mW/cm²) x Time (Seconds)] / 1000

Recommended Dosage Guidelines

Research suggests that different goals require different energy levels. This concept is known as the Arndt-Schulz Law, which states there is a "therapeutic window"—too little light has no effect, while too much can actually inhibit cellular function.

Treatment Goal	Recommended Dosage	Tissue Depth
Skin Health / Anti-aging	3 – 10 J/cm²	Superficial
Muscle Recovery	20 – 40 J/cm²	Deep
Joint Pain / Inflammation	30 – 60 J/cm²	Deep

Example Calculation

If your device provides 50 mW/cm² at a distance of 6 inches, and you use it for 10 minutes (600 seconds):

1. 50 mW/cm² x 600 seconds = 30,000
2. 30,000 / 1000 = 30 J/cm²

This session would be ideal for deeper tissue recovery or addressing inflammation in the joints.

Tips for Better Results

• Check Distance: Irradiance drops significantly as you move away from the light. Always check the manufacturer's charts for the specific irradiance at different distances (e.g., 6″, 12″, 18″).
• Consistency Over Power: It is usually better to have consistent, moderate-dosage sessions rather than one massive dose per week.
• Skin Contact: If using a wrap or pad, the irradiance is usually much higher because there is zero distance between the LEDs and the skin.