20-20-20 Rule Compliance Interval Timer Helper

Named20min/20ft/20 sec reminder arithmetic from supplied observations; does not schedule an OS timer or establish eye health. Caller independently establishes matching units, evidence, method edition and applicability; output is not compliance, diagnosis, work-safety approval, geological identity or validated hazard prediction.

Description

The 20-20-20 mnemonic links elapsed viewing time with a distant look and a short break.

The 20-20-20 mnemonic links elapsed viewing time with a distant look and a short break.^[1]

Arithmetic reserves for entered measurements do not run a clock, schedule reminders or establish a medical assessment. Use this tool to calculate reserves for entered break observations.

When to use 20-20-20 Rule Compliance Interval Timer Helper

Use this tool to calculate reserves for entered break observations. Establish the observation protocol, units, task and reference population or review criterion before entering measurements.

How to use 20-20-20 Rule Compliance Interval Timer Helper and understand its results

Establish the observation protocol, units, task and reference population or review criterion before entering measurements.
Enter observedScreenMinutesSinceBreak, observedLastDistanceFeet, observedLastBreakSeconds, using the field meanings and rules below, then run the tool.
Read minutesUntilNamed20MinuteReminder, signedDistanceFeetReserve, signedBreakSecondsReserve. Interpret the fields using their units, signs and evidence conventions below.
If input validation fails, correct the reported field and run again. Before applying the result, check reference scope, model assumptions and any missing evidence or placeholder values.

Input field	Meaning	Value type	Requirement
observedScreenMinutesSinceBreak	Observed screen minutes since break	number	Required
observedLastDistanceFeet	Observed last distance feet	number	Required
observedLastBreakSeconds	Observed last break seconds	number	Required

Enter nonnegative minutes since a break, viewing distance in feet and break duration in seconds. Return max(0,20−minutes), distance−20 and duration−20. These are numerical reserves for entered observations; no clock, alert, background scheduling or treatment assessment is implemented.

minutesUntil=max(0,20−elapsedMinutes); distanceReserveFeet=distanceFeet−20; durationReserveSeconds=durationSeconds−20

Use the exact units, boundary rules, ordering and missing-evidence conventions above.

Output field	Meaning	Value type
minutesUntilNamed20MinuteReminder	Minutes Until Named20 Minute Reminder; follow the units, sign, ordering and evidence convention stated above	number
signedDistanceFeetReserve	Signed Distance Feet Reserve; follow the units, sign, ordering and evidence convention stated above	number
signedBreakSecondsReserve	Signed Break Seconds Reserve; follow the units, sign, ordering and evidence convention stated above	number

json

{
  "input": {
    "observedScreenMinutesSinceBreak": 25,
    "observedLastDistanceFeet": 25,
    "observedLastBreakSeconds": 15
  },
  "output": {
    "minutesUntilNamed20MinuteReminder": 0,
    "signedDistanceFeetReserve": 5,
    "signedBreakSecondsReserve": -5
  }
}

Limitations and assumptions

Arithmetic reserves for entered measurements do not run a clock, schedule reminders or establish a medical assessment. Interpretation depends on the units, sampling scope and exact model described above.

All listed fields require explicit values. Unexpected fields, incorrect types, nonfinite numbers and sparse evidence arrays fail validation; the specific bounds and alignment requirements are stated above. Extremely large inputs or outputs can also be rejected. An input error is distinct from a successful result reporting false, no matches or missing evidence.

Alternative or Complementary methods

Use Anthropometric Eye Height Seated Monitor Fit Checker for this related task: Eye and monitor-center heights determine a signed vertical viewing angle.

Use Contrast Ratio Paper-Screen Reading Comfort Checker when its separate inputs and assumptions fit the question: Paper-to-screen luminance can be compared through a signed natural-log ratio.

References

20-20-20 Rule Compliance Interval Timer Helper — tool.io

Similar or alternative tools

Anthropometric Eye Height Seated Monitor Fit Checker
Eye and monitor-center heights determine a signed vertical viewing angle.
Contrast Ratio Paper-Screen Reading Comfort Checker
Paper-to-screen luminance can be compared through a signed natural-log ratio.