Everyday Life Calculators
Seven small calculators for the everyday decisions — splitting a bill, checking a discount is real, and working out which pack is actually cheaper.
Restaurant maths, solved
The Tip Calculator works out the tip and the total, and the Split Bill Calculator divides it between any number of people — including the awkward case where the split is uneven because two people had the tasting menu. Both handle the service-charge-already-included case, which is where mental arithmetic usually goes wrong.
Is it actually a good deal?
Two tools cover most of retail. The Discount Calculator turns a percentage off into the price you will actually pay, and reverses it to show what discount a "was/now" price really represents. The Unit Price Calculator is the more useful of the pair: it converts different pack sizes into a common price per unit, which is the only honest way to compare a 750 ml bottle against a 1.5 litre one. Supermarket shelf labels are supposed to do this and frequently use inconsistent units.
Costs that depend on distance and quantity
The Fuel Cost turns distance, fuel economy and pump price into the cost of a journey — useful for comparing driving with the train, or for splitting a road trip fairly. The Recipe Scaler multiplies ingredients up or down for a different number of servings, keeping the ratios right, which matters far more in baking than in cooking.
Something a bit different
The Family Tree Maker is the outlier here: not a calculator at all, but a chart builder. A person can hold any number of partnerships, two people already on the chart can be married to each other, and the finished tree exports as a PNG, a PDF of the chart alone, or a GEDCOM file for genealogy software. It runs entirely in your browser and nothing is uploaded.