實際上，“一炷香”並不是時間單位，受環境、風力、諸多因素影響，一炷香燃燒時間並完全相同，古人説“一炷香時間”是十五分鐘到時。
“一炷香”、“一盞茶”中國古代説法，英語中有許多古老、奇怪時間單位，人類文明發展，有些成為歷史，提起，但這並不妨礙我們瞭解這些知識。
Note: contraption 裝置，新奇玩意兒A lustre is a period of five years. Its use dates back to Ancient Rome, when a lustrum was a five-year period at the end of which a full census of the Roman population would be carried out. Once the figures were in and the counting was complete, a vast celebratory procession would be held through the streets of Rome, which culminated in a vast purifying sacrifice called a lustratio (literally, “a washing”) made in honor of all of the people of the Empire.“lustre”表示五年時間。
然而，古英語中，原子代表當時認為可測量時間量：人們認為一分鐘內有376原子，一原子接近1/6秒（更準確地説是0.15957秒）。
In the Middle Ages, all kinds of contraptions and devices were used to keep track of time, one of the simplest and neatest of which was an Indian water-clock called a ghurry. It comprised a large metal or wooden bowl, pierced with several holes, which would be placed in a basin full of water, and as the water poured into the bowl through the holes in its sides, it would slowly sink to the bottom of the tank. The entire process from start to finish took a fixed amount of time, which was usually precisely 24 minutes. Ultimately, there were once considered to be 60 ghurries in a day.中世紀，人們發明瞭各種各樣時間計量裝置，其中是印度水鍾（稱為“ghurry”）。
這種水鍾一個帶有數個小孔金屬或木製大碗組成，碗放在裝滿水盆裏，水通過碗上孔流入碗中時，碗會沉到水底部。
整個過程所用時間是，是24分鐘。
人們認為一天有60“ghurries”。
Note: contraption 裝置，新奇玩意兒A lustre is a period of five years. Its use dates back to Ancient Rome, when a lustrum was a five-year period at the end of which a full census of the Roman population would be carried out. Once the figures were in and the counting was complete, a vast celebratory procession would be held through the streets of Rome, which culminated in a vast purifying sacrifice called a lustratio (literally, “a washing”) made in honor of all of the people of the Empire.“lustre”表示五年時間。
關於“lustre”歷史可以追溯到古羅馬時期，“lustrum”當時指五年週期，每這個週期結束，羅馬進行一次全面人口普查。
普查結束時，羅馬街頭會出現慶祝遊行，一場稱為“lustratio”淨化祭祀結束，紀念所有羅馬帝國人民。
If a “light-year” sounds like a unit of time but is actually a unit of distance, then a mileway is the complete opposite. It sounds like a unit of length, but in the early Middle Ages it was actually a name for a period of around 20 minutes—or roughly the amount time it takes to walk one mile.“光年”聽起來像是表示時間單位，實際上是距離單位。
而“mileway（英里路）”則完全相反，它聽起來像是長度單位，但中世紀初期，“mileway”表示20分鐘或步行一英里所需時間。
A nundine was a Roman market held every ninth day, which takes its name from the Latin word for “ninth,” novem (as in November, the ninth month of the Roman calendar). A nundine, ultimately, is a period of nine days—or, not counting inclusively, an eight-day gap between two dates.“Nundine”是指羅馬集市日，每九天舉辦一次，它來源於拉丁語中“novem（第九，像November即11月是羅馬曆法中第9個月）”。
來進行劃分，有時一炷香、三十分鐘一炷香、一刻鐘一炷香。
延伸閱讀…
Note: nundine 古羅馬曆法，每九天舉行一次集市日Derived from the Greek words for “night” (nyks) and “day” (hemera), a nychthemeron is nothing more than a fancy alternative name for a period of 24 hours.“Nychthemeron（一晝夜）”源自希臘語“夜”（nyks）和“日”（hemera），“nycthemeron”不過是24時。
Note: nychthemeron 一天一夜，一晝夜Also called a point or a prick, in Medieval Europe a punct was a quarter of an hour… 假如光字面上古代一炷香燒完一炷香需要時間，當時一炷香可能有些，是人工製作而成。
古人計時需要借用日晷、漏壺工具，燃香計時是而常用計時方法。
那麼一炷香是多時間呢?於環境、風力、、香料乾濕諸多因素，一炷香燃燒時間並完全相同，但半個時辰，即時。
古代一炷香來計時，還可用一盤香、一爐來計時。
來進行劃分，有時一炷香、三十分鐘一炷香、一刻鐘一炷香。
延伸閱讀…
古代有一種長盤香，能夠持續燃燒十二個時，盤香上面有大小不一刻度，來計時。
其實用來計時話，誤差，但是古代受到各種條件制約，盤香成為常用計時工具之一。
所以，一炷香有多是沒有概念。
有人想問了，一炷香説法是從哪裏來呢?“一柱香”時間這個概念起緣於僧人打坐，僧人燃燒為計時方法，如僧人“打禪七”時一天要打11柱香，中間休息20分鐘。
這裏11炷時間並不是，主要指是只有這11炷燃燒完畢這一天打禪功課才算完成。
寺廟當中可能是這樣方式計算時間。
仔細想想，當時，這是一個方法了，受白天黑夜影響，攜帶，製作簡，且能營造氣氛。