Explore scientific quantities and the calculations that connect them.
How to calculate shelf life and time remaining
Calculate elapsed days, remaining days and percentage remaining with a moving calendar timeline. The example also explains why calendar arithmetic cannot establish product safety.
How to convert µmol/L to mg/dL
Convert amount concentration into mass concentration by following the substance and every unit. A creatinine example shows where the factor of 10,000 comes from.
How to estimate paper thickness from GSM
Derive paper thickness from mass per area and density, track the square-centimeter conversion, and see why equal GSM does not guarantee equal thickness.
How to calculate battery health percentage
Compare current full-charge capacity with original design capacity to calculate capacity-based battery health, and separate that long-term measure from today's charge level.
How to calculate a liquid dilution ratio
Name the concentrate-to-water ratio, count its equal parts, size a 22-fluid-ounce batch, check the mix, and distinguish product share from active-ingredient concentration.