How it works
Calculations
Every calculation runs in your browser with the formula shown on each tool page. Dates are calculated as whole calendar days, so clock changes and midnight do not shift results. Units are stored as entered and converted only for display.
Records
Recording tools let you add, edit, delete (with a short undo), filter by date, chart and export entries. Empty fields stay empty: they are never treated as zero.
Schedules and reference data
Only verified, dated schedule packs create automatic dates. The England vaccination pack and England screening baselines are dated and reviewed at least every 90 days. Where a pack is not verified, such as the Nigeria vaccination schedule, the tool works as a manual record. Growth comparisons use official WHO tables.
Timers
Timers store start and stop times rather than counting ticks, so time is recalculated correctly if your phone locks or the tab sleeps. Timers are logs, not monitoring.
Example stories (fictional)
These short examples are made up and are not anyone’s records.
- Ada notes her period start dates for three months and takes a printed summary to her appointment.
- Sam times contractions on the way to the maternity unit and shows the midwife the table, while following the unit’s advice by phone.