Foot per minute (ft/min) is a fascinating unit of speed often used in specialized fields such as HVAC (heating, ventilation, and air conditioning) systems to measure airflow and in other engineering applications. Interestingly, the roots of this unit can be traced back to the historical origins of the foot as a measurement, which dates back to ancient Egypt where the “royal foot” was utilized. Over centuries, various civilizations have adopted and adapted the foot, leading to the version we use today.
While it might seem esoteric, ft/min is crucial for ensuring precise calibrations and ensuring optimal efficiency in engineering contexts. For example, it is heavily relied upon to ensure the right amount of air changes per hour in room ventilation, directly affecting air quality and energy efficiency. Understanding and utilizing this unit connects us to a broader narrative of measurement evolution and technical precision.
The knot, a unit of speed equal to one nautical mile per hour, has its origins in the age of sail. Mariners used a device known as the “common log” to measure a ship’s speed. This involved a wooden log attached to a rope with knots tied at uniform intervals. By counting the knots that passed through a sailor’s hands over a set period, they could determine the ship’s speed. Today, knots remain an essential measure in aviation and maritime contexts, underscoring how deeply it is embedded in navigation traditions.
Interestingly, the nautical mile, corresponding to one minute of latitude, is roughly 1.1508 miles. This makes the knot not only a unique unit for speed but also a reminder of the Earth’s curvature and ancient navigation skills.
Feet per minute | Knots |
---|---|
0
ft/min
|
0
knot
|
10
ft/min
|
0.098747
knot
|
20
ft/min
|
0.197494
knot
|
30
ft/min
|
0.296241
knot
|
40
ft/min
|
0.394988
knot
|
50
ft/min
|
0.493735
knot
|
60
ft/min
|
0.592482
knot
|
70
ft/min
|
0.691229
knot
|
80
ft/min
|
0.789976
knot
|
90
ft/min
|
0.888723
knot
|
100
ft/min
|
0.98747
knot
|
110
ft/min
|
1.08622
knot
|
120
ft/min
|
1.18496
knot
|
130
ft/min
|
1.28371
knot
|
140
ft/min
|
1.38246
knot
|
150
ft/min
|
1.48121
knot
|
160
ft/min
|
1.57995
knot
|
170
ft/min
|
1.6787
knot
|
180
ft/min
|
1.77745
knot
|
190
ft/min
|
1.87619
knot
|
200
ft/min
|
1.97494
knot
|
210
ft/min
|
2.07369
knot
|
220
ft/min
|
2.17243
knot
|
230
ft/min
|
2.27118
knot
|
240
ft/min
|
2.36993
knot
|
250
ft/min
|
2.46868
knot
|
260
ft/min
|
2.56742
knot
|
270
ft/min
|
2.66617
knot
|
280
ft/min
|
2.76492
knot
|
290
ft/min
|
2.86366
knot
|
300
ft/min
|
2.96241
knot
|
310
ft/min
|
3.06116
knot
|
320
ft/min
|
3.1599
knot
|
330
ft/min
|
3.25865
knot
|
340
ft/min
|
3.3574
knot
|
350
ft/min
|
3.45615
knot
|
360
ft/min
|
3.55489
knot
|
370
ft/min
|
3.65364
knot
|
380
ft/min
|
3.75239
knot
|
390
ft/min
|
3.85113
knot
|
400
ft/min
|
3.94988
knot
|
410
ft/min
|
4.04863
knot
|
420
ft/min
|
4.14737
knot
|
430
ft/min
|
4.24612
knot
|
440
ft/min
|
4.34487
knot
|
450
ft/min
|
4.44362
knot
|
460
ft/min
|
4.54236
knot
|
470
ft/min
|
4.64111
knot
|
480
ft/min
|
4.73986
knot
|
490
ft/min
|
4.8386
knot
|
500
ft/min
|
4.93735
knot
|
510
ft/min
|
5.0361
knot
|
520
ft/min
|
5.13485
knot
|
530
ft/min
|
5.23359
knot
|
540
ft/min
|
5.33234
knot
|
550
ft/min
|
5.43109
knot
|
560
ft/min
|
5.52983
knot
|
570
ft/min
|
5.62858
knot
|
580
ft/min
|
5.72733
knot
|
590
ft/min
|
5.82607
knot
|
600
ft/min
|
5.92482
knot
|
610
ft/min
|
6.02357
knot
|
620
ft/min
|
6.12232
knot
|
630
ft/min
|
6.22106
knot
|
640
ft/min
|
6.31981
knot
|
650
ft/min
|
6.41856
knot
|
660
ft/min
|
6.5173
knot
|
670
ft/min
|
6.61605
knot
|
680
ft/min
|
6.7148
knot
|
690
ft/min
|
6.81354
knot
|
700
ft/min
|
6.91229
knot
|
710
ft/min
|
7.01104
knot
|
720
ft/min
|
7.10979
knot
|
730
ft/min
|
7.20853
knot
|
740
ft/min
|
7.30728
knot
|
750
ft/min
|
7.40603
knot
|
760
ft/min
|
7.50477
knot
|
770
ft/min
|
7.60352
knot
|
780
ft/min
|
7.70227
knot
|
790
ft/min
|
7.80101
knot
|
800
ft/min
|
7.89976
knot
|
810
ft/min
|
7.99851
knot
|
820
ft/min
|
8.09726
knot
|
830
ft/min
|
8.196
knot
|
840
ft/min
|
8.29475
knot
|
850
ft/min
|
8.3935
knot
|
860
ft/min
|
8.49224
knot
|
870
ft/min
|
8.59099
knot
|
880
ft/min
|
8.68974
knot
|
890
ft/min
|
8.78849
knot
|
900
ft/min
|
8.88723
knot
|
910
ft/min
|
8.98598
knot
|
920
ft/min
|
9.08473
knot
|
930
ft/min
|
9.18347
knot
|
940
ft/min
|
9.28222
knot
|
950
ft/min
|
9.38097
knot
|
960
ft/min
|
9.47971
knot
|
970
ft/min
|
9.57846
knot
|
980
ft/min
|
9.67721
knot
|
990
ft/min
|
9.77596
knot
|
1000
ft/min
|
9.8747
knot
|
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