What this result means
Enter the average daily duration shown by your device. The calculator multiplies that duration across fixed 7-day, 30-day and 365-day periods and shows the arithmetic without rating it. [1]
How the screen-time projection works
The calculator converts the daily hours and minutes into one exact minute total, multiplies by 7, 30 and 365, then converts those totals back to hours. The annual full-day equivalent divides annual hours by 24. [1]
For transparency, 30 days is labelled as a fixed period rather than called an average calendar month.
Use a like-for-like daily average
Use an average from the device or service you want to understand. If several devices count overlapping time, adding their averages can double-count the same period.
Device definitions can include different apps, categories or background behaviour. Keep the source and reporting period consistent when comparing two projections.
What the result does and does not mean
The result is a duration projection, not a judgement. It does not know why a screen was used, what happened during that time or whether uses overlapped.
A larger result is not automatically worse, and a smaller result is not automatically better. Work, accessibility, learning, communication and leisure can all contribute to the same total.
Privacy and limitations
The calculation runs locally in your browser. The duration and results are not placed in the URL or sent as analytics details. Sharing sends only the public tool link.
The projection assumes the same daily average throughout each fixed period. It does not forecast changing routines, seasonal patterns, travel or a leap year.
Formula and assumptions
- Formula
- Daily minutes = hours × 60 + minutes. Period total = daily minutes × 7, 30 or 365. Equivalent full days = annual minutes ÷ 1,440. [1]
- Version
- Daily duration projection, daily-screen-time-duration-v1
- Rounding
- Convert the entered whole hours and minutes to exact integer minutes. Multiply before converting to hours or 24-hour days, then display at most two decimal places. The 30-day result is explicitly a fixed 30-day period, not a calendar-month average.
- Worked example
- Example: 3 hours 30 minutes is 210 minutes per day. Across 7 days that is 1,470 minutes, or 24.5 hours. Across 365 days it is 1,277.5 hours, equivalent to about 53.23 full 24-hour days. [1]
Who this is for — and when not to use it
Intended use
Neutral projection of a device-reported or self-estimated average daily screen-time duration across fixed periods.
Not intended for
This tool does not measure wellbeing, productivity, sleep, addiction, eye health, mental health or child development, and it does not set a target or recommend behaviour change.
Exclusions
- Health, wellbeing, productivity, addiction or developmental assessment
- Recommended limits, scores, categories, goals and behaviour-change plans
- Combining overlapping screen use across multiple devices
- Deciding whether device-reported activity was active, passive or background use
- Calendar-month totals, leap-year adjustment and predictions of future behaviour
Evidence sources
- 1. SP 330, Section 4: Non-SI units accepted for use with the SI — National Institute of Standards and Technology. Accessed Aug 21, 2026.