Build your own
medieval monument.

Years = stone volume × 1.1 ÷ (workers × 0.06 m³ per worker per day × 0.6 for a skilled crew × stone supply) ÷ (1 − idle time) ÷ 365. Stone supply is 0.85, 0.7 or 0.5, depending on how far the stone travels. Seasons are not modelled separately: winter breaks belong to the idle time. All factors are our assumptions, not measured facts. The model is linear: twice the crew means half the time. Real sites met limits such as space on the scaffolding, stone supply and skilled masons, so very large crews would not have worked this efficiently.

The average crew of the original is the crew that would have needed exactly the recorded time at typical stone supply, working without a break. Real crews changed from season to season and real sites stood still, so treat it as a model value. Because of this, picking the original's stone route can still change the result: the original crew is calculated with typical (regional) supply.

The stone volumes are our own estimates from published dimensions, shown as a range. Interior air volume, such as the 200,000 m³ often quoted for Amiens, is not stone.

Historical Builder is a free calculator for anyone curious about medieval architecture. Choose one of 24 real castles and cathedrals, see what the sources say about its building period, and then change the crew, the stone supply, the idle time and the size of the building to find out how long your own version would take. It is meant for visitors planning a trip to European castles and cathedrals, readers of historical novels, history students and teachers, and writers or game builders who need believable construction times.

Castles: Krak des Chevaliers and Margat (Syria), Kerak (Jordan), Beaufort (Lebanon), Château Pèlerin at Atlit (Israel), Kyrenia (Cyprus), Miravet, Peñíscola and Calatrava la Nueva (Spain), Dover and Rochester (England), Beaumaris (Wales). Cathedrals: Notre-Dame de Paris, Chartres, Amiens, Reims and Strasbourg (France), Cologne (Germany), Canterbury, Salisbury and York Minster (England), Milan (Italy), Burgos and Seville (Spain).

Read more: Castles: Krak des Chevaliers · Margat · Kerak · Beaufort · Château Pèlerin / Atlit · Kyrenia Castle · Miravet · Peñíscola · Calatrava la Nueva · Dover Castle · Rochester Castle · Beaumaris Castle. Cathedrals: Notre-Dame de Paris · Chartres Cathedral · Amiens Cathedral · Reims Cathedral · Strasbourg Cathedral · Cologne Cathedral · Canterbury Cathedral · Salisbury Cathedral · York Minster · Milan Cathedral · Burgos Cathedral · Seville Cathedral.

Every building is treated the same way: the period comes from a named source, the stone volume is our own estimate from published dimensions, and the result is a simple model, not a measured fact.