Screen Time Impact Calculator Formula

Understand the math behind the screen time impact calculator. Each variable explained with a worked example.

Use the Screen Time Impact Calculator

Formulas Used

Total Daily Screen Time

total_hours = total_screen

Health Impact Score

impact_score = min(total_screen * 5 + screen_before_bed, 100)

Recommended Break Interval

eye_break_interval = 20

Yearly Screen Time

yearly_hours = total_screen * 365

Variables

VariableDescriptionDefault
work_screen_hoursWork Screen Time(hours)8
leisure_screen_hoursLeisure Screen Time(hours)3
screen_before_bedScreen Use Before Bed15
total_screenDerived value= work_screen_hours + leisure_screen_hourscalculated

How It Works

Screen Time Health Impact

Impact Scoring

  • Each hour of screen time adds 5 points
  • Screen use before bed adds up to 15 points for sleep disruption

    • The 20-20-20 Rule

    Every 20 minutes, look at something 20 feet away for 20 seconds to reduce eye strain.

    Guidelines

    ScoreImpact 0-30Low impact 31-55Moderate (use 20-20-20 rule) 56-75High (consider reducing) 76+Very high (take action)

    Worked Example

    8 hours work + 3 hours leisure, screens until bedtime.

    work_screen_hours = 8leisure_screen_hours = 3screen_before_bed = 15
    1. 01Total screen time = 8 + 3 = 11 hours
    2. 02Impact score = 11 x 5 + 15 = 70 (High)
    3. 03Yearly hours = 11 x 365 = 4,015 hours

    Frequently Asked Questions

    How much screen time is too much?

    There is no universal limit for adults, but more than 2 hours of leisure screen time is associated with lower well-being. Take regular breaks and avoid screens before bed.

    Does blue light affect sleep?

    Yes. Blue light from screens suppresses melatonin production. Avoiding screens 1-2 hours before bed or using blue light filters can improve sleep quality.

    What is computer vision syndrome?

    Also called digital eye strain, it includes symptoms like dry eyes, headaches, blurred vision, and neck/shoulder pain from prolonged screen use. The 20-20-20 rule helps prevent it.

    Ready to run the numbers?

    Open Screen Time Impact Calculator