WWW Unit Converter Converts one type of unit to another (e.g., feet to meters, US bushels to liters, etc.)
Calculation and Conversion Tools The Internet Public Library’s collection of links to online calculators and conversion tools for such things as weights, measures, Roman numerals, and currencies.
ConvertAuto.com Another collection of handy conversion tools, created by Lilly Hammond.
Wages and Prices in Europe Hyperlist of websites containing statistical data on wages and prices (including currency exchange rates) in Europe, from the medieval period to the present. Sites include the Medieval and Early Modern Data Bank.
Purchasing Power of British Pounds, 1245-present An online calculator by Lawrence H. Officer; part of a broader collection of economic calulators for measuring relative worth over time called MeasuringWorth.com.
UK Annual Inflation Rates, 1265-present Another online calculator by Lawrence H. Officer from MeasuringWorth.com.
UK Earnings and Prices, 1264-present Another online calculator by Lawrence H. Officer from MeasuringWorth.com, based on three data bases: the “consumer” price index, average nominal earnings, and average real earnings.
Russ Rowlett, A Dictionary of Units of Measurement Extemely useful. Prof. Rowlett is the Director of the Center for Mathematics and Science Education at the University of North Carolia, Chapel Hill.
Medieval Crop Yields Database (1211-1491) The largest and most precise database on pre-modern grain harvests currently available internationally. Based on medieval English manorial accounts (including the Bishopric of Winchester Pipe Rolls), and assembled by Bruce Campbell from his own work and that of other historians, especially Jan Titow and David Farmer. Searchable bycrop, harvest year, manor, estate, county, region, and any combination of the same. A “Chronologies” facility also offers a valuable series of reconstructed annual chronologies for each of the principal crops and combinations of the same.