Calculator Inputs
What this measures
This calculator combines time, intensity, distance, and evening timing into a practical score for daily tracking.
- Score: 0–100 exposure estimate.
- Band: Low, Moderate, High.
- Exports: CSV and PDF after calculation.
Mental health angle
Evening light can influence sleep timing, which affects mood stability, focus, and stress resilience over time.
Formula Used
The calculator uses a weighted exposure model that blends intensity and timing:
- DeviceFactor reflects typical screen output and use patterns.
- BrightnessFactor is brightness% ÷ 100 (weighted near max).
- DistanceFactor uses 50 cm ÷ distance, with safety clamps.
- TimingFactor adds up to 40% based on evening share.
- Modifiers include filter strength, warm mode, lenses, breaks, age, and sensitivity.
These are practical estimates for self-tracking, not device-lab measurements.
How to Use This Calculator
- Enter your total screen time for a typical day.
- Select the device you use most, then set brightness and distance.
- Add your evening screen time after about 7pm.
- Choose your filtering, warm mode, and lens options.
- Enter break frequency and your sensitivity to light.
- Press Calculate Exposure to see results above the form.
- Export CSV or PDF to track progress over time.
Example Data Table
| Day | Hours | Evening Hours | Brightness | Distance | Filter | Breaks/hr | Score | Band |
|---|---|---|---|---|---|---|---|---|
| Mon | 4.0 | 1.0 | 60% | 55cm | Light | 2 | 32 | Low |
| Wed | 6.5 | 3.0 | 80% | 45cm | None | 1 | 68 | High |
| Sat | 5.0 | 2.0 | 70% | 60cm | Strong | 3 | 41 | Moderate |
Use the table idea to log daily changes and compare trends.
Screen light and daily rhythm
Light in the blue range supports alertness during daytime. When exposure shifts later, the brain may treat it like morning light, nudging bedtime later and shortening wind‑down. This calculator highlights timing by boosting scores when evening hours rise. Tracking that share helps users link habits with next‑day mood, focus, and energy.
How the exposure score is built
The score combines duration, brightness, and distance into a practical index from 0 to 100. Device factors reflect typical use patterns, while distance uses a 50 cm reference that scales intensity up when you sit closer. Timing can add up to 40% when most use occurs after 7pm. Filters, warm modes, lenses, and breaks then reduce the estimate, so improvements remain visible even when total hours stay constant.
Interpreting bands for planning
Low exposure generally supports stable evenings when other routines are healthy, such as regular wake time and dim room lighting. Moderate exposure suggests targeted adjustments, especially for late sessions that overlap with relaxation time. High exposure signals that multiple inputs are stacking: long hours, high brightness, close viewing, and limited breaks. Use the band as a planning flag, not a diagnosis, and recheck after changing one variable at a time.
Actionable levers that move results
Users typically see the fastest improvement by cutting evening screen time first, because timing influences both alertness and perceived strain. Next, lower brightness and increase distance; both reduce intensity without changing tasks. Add at least one micro‑break per hour, and consider stronger filtering after sunset. Pair this with a brief pre‑sleep routine, like reading on paper or stretching, to protect consistency. Compare exports week to week to confirm changes.
Using exports for personal trends
CSV downloads help build a simple log of inputs, scores, and bands that can be sorted by day type, such as workdays versus weekends. Add a column for sleep quality, headache frequency, or mood rating and look for patterns across seven days. PDF reports work well for coaching sessions or personal reflection, because they keep the context of your settings. Over time, a downward score trend can confirm that small changes are adding up and staying sustainable.
FAQs
Is the exposure score a medical measurement?
No. It is an educational estimate that blends time, brightness, distance, and timing. Use it to compare habits across days, not to diagnose conditions.
Why does evening screen time increase the score?
Light later in the day can interfere with normal wind‑down cues. The calculator applies extra weight to evening share to reflect higher sensitivity near bedtime.
How can I lower my score without reducing total hours?
Reduce brightness, sit farther away, enable warm color modes, and use stronger filtering after sunset. Add regular micro‑breaks to lower the strain estimate.
What distance should I enter if I switch setups?
Use your typical distance for the device you selected. If you split time, choose the setup used most and rerun the calculator for the second setup to compare.
Do blue‑light lenses always help?
They can reduce part of the blue spectrum, but effects vary by lens design and use timing. Treat the glasses option as a modest reduction, not a complete solution.
How should I use CSV and PDF exports?
Save CSV results daily to track trends, then add your own notes like sleep quality. Use PDF reports when you want a clean summary to review or share.