Methods and sources
Where each tool’s answer comes from, and how far it has got.
| Tool | Where the answer comes from | Right now |
|---|---|---|
| Child height percentile calculator | The chosen standard’s LMS parameters turn the height into a z-score, then a percentile. | Compared with peers |
| Height growth calculator | Later minus earlier; dates subtracted on the calendar. No health threshold is involved. | Answers now |
| Growth chart maker | Your own dates and values, spaced by date. No reference bands underneath. | Answers now |
| Height percentile to centimetres | The same LMS parameters as the forward calculator, solved the other way round. | Compared with peers |
| Child weight percentile calculator | The chosen standard’s LMS parameters turn the weight into a z-score, then a percentile. | Compared with peers |
| Weight change calculator | Units matched, then later minus earlier; dates subtracted on the calendar. | Answers now |
| Child BMI calculator | Weight in kilograms divided by height in metres squared. The placing comes from a BMI-for-age table. | Compared with peers |
| Visual acuity notation converter | Decimal = 1 ÷ minimum angle of resolution. Three scales for one quantity, so conversion is arithmetic. | Answers now |
| Screen and outdoor time reference | Published guidance retrieved by age and source, keeping each source’s own definition of the time. | Not available yet |
| Tooth eruption timing | The source table’s eruption age range, retrieved by tooth type and position. | Not available yet |
| Children’s sleep duration reference | Published guidance retrieved by age and source, keeping each source’s own basis for the figure. | Not available yet |
| Sleep duration calculator | Time in bed, minus minutes awake in the night, plus that day’s nap. | Answers now |
| Nutrient reference intake lookup | Reference intakes retrieved by age, sex and nutrient, keeping the source’s value type and unit. | Not available yet |
| Feeding and diet reference | Published guidance retrieved by source, age and topic, keeping the original units and scope. | Not available yet |
| Nutrition label intake calculator | Label amount × portion eaten ÷ the label’s reference amount. | Answers now |
Sources are chosen by question, not by language.
Tools with a regional reference name the region, the version, the ages covered and how the measurement was defined. Reading the site in another language does not change the reference — those are two different things. Where coverage runs out, it says so.