Your measurement expressed in each ancient unit — on a logarithmic scale, since a digitus and a parasang live five orders of magnitude apart.
Reading ancient distances: the Roman system is a body chained together — 16 finger-widths to the foot, 5 feet to the pace (a double step), 1,000 paces to the mile: mille passus, literally "a thousand paces." The Greek stadion named the stadium, and the Egyptian iteru measured the Nile itself, about 10.5 km per "river unit." All values are the conventional scholarly reconstructions — regional standards varied by a few percent, and that's part of the story (see How They Measured).
Convert ancient length units — Roman feet, paces, stadia and miles, Greek pous and stadion, Egyptian royal cubits, khet and iteru, Persian parasangs, biblical cubits — to meters, feet, kilometers and miles, with legion marching times for long distances.
From the obol — a coin light enough to carry in the mouth, and buried with the dead as the ferryman's fare — to the Babylonian talent, on a log scale.
Weight was money: before coins, silver was weighed out — so the same words name both. A drachma is a weight and a coin; a shekel is a weight and a currency; the Roman libra survives in "lb" and the £ sign alike, and its twelfth part, the uncia, became both the ounce and the inch. For scale (not conversion): a drachma was a skilled Athenian's fair daily wage, which makes a talent about sixteen years of work — the sum entrusted in the biblical parable.
Convert ancient weight units — Greek talents, minae, drachmae and obols, Roman librae, unciae and scruples, Egyptian deben and qedet, Babylonian shekels and talents — to grams, kilograms, ounces and pounds.
From the cyathus ladle that portioned wine at a Roman dinner to the culleus — a whole ox-hide of it — on a log scale.
Grain ruled the granary: the Greek choinix was one person's daily grain ration — an army's logistics were counted in it — and the Egyptian hekat was the unit the pyramid-builders' beer and bread were reckoned in; scribes tracked it with the famous Eye-of-Horus fractions, halves down to sixty-fourths. Liquid and dry measures were separate worlds then as now: our gallon split the same way centuries later.
Convert ancient volume units — Roman cyathus, sextarius, congius, urna, amphora and culleus, Greek kotyle, choinix, chous, metretes and medimnos, Egyptian hin, hekat and khar — to milliliters, liters and gallons.
From a single square Roman foot to the centuria — the 100-family land grant whose survey grids are still visible from the air across Italy — on a log scale.
Built from the foot up: Roman land measures are the length system squared — an actus is 120 feet, a square actus is a plowing strip, two of them make the iugerum ("a yoking"), two iugera the heredium ("an inheritance," one family's allotment), and a hundred heredia the centuria. Egyptian surveyors worked the same way from the royal cubit: the setat is a square of 100 cubits per side, re-measured every year after the Nile flood erased the boundary stones — the birth of geometry, literally "earth-measuring."
Convert ancient land units — Roman square feet, square actus, iugera, heredia and centuriae, Greek plethra, Egyptian setat — to square meters, hectares and acres.
"A foot" meant a different length in every land and era — here are five of the best-documented, in millimeters. Only in 1959 did the English-speaking world finally nail its foot to exactly 304.8 mm.
The honesty box, in full: every ancient value in this tool is a conventional modern reconstruction, anchored to surviving artifacts — cubit rods, weight stones, coins, measuring vessels, and surveyed monuments. Real standards drifted between cities, provinces, and centuries, typically by a few percent and sometimes far more. The ratios, though, were the law: 16 digits to the foot, 48 sextarii to the amphora, 6,000 drachmae to the talent — and this tool is built on exactly those ratios, so its internal arithmetic is the ancients' own.
How ancient measurement worked — body-based units, Egyptian cubit rods, why twelfths and sixtieths ruled, the pre-metric marketplace chaos, the birth of the meter, and Roman land surveying.