How do inHg, kPa and mmHg relate when reading vacuum gauges on penis pumps?
Executive summary
Vacuum units on penis-pump gauges — inches of mercury (inHg), kilopascals (kPa) and millimetres of mercury (mmHg) — are plainly interconvertible and represent the same physical vacuum expressed in different scales, so users can read any one and convert to the others with fixed factors [1] [2]. Practical reading requires remembering that vacuum gauges usually show pressure relative to ambient (gauge vacuum, negative values from 0), that common safe community guidance centers around modest vacuum levels (about 3–6 inHg), and that converting units is straightforward math rather than a difference in device performance [3] [4] [5].
1. How the units map to each other: fixed conversion factors
The relationship between the units is fixed: 1 inch of mercury equals about 3.38639 kPa and corresponds to roughly 25.4 mmHg (derived from standard atmosphere relationships such as 29.92 inHg = 760 mmHg) so multiplying or dividing by those factors converts one unit to another [1] [6]. Millimetres of mercury (mmHg) and Torr are effectively equivalent for gauge work (1 Torr ≈ 1 mmHg = 133.322 Pa), giving another route to convert via pascals if needed [2]. Online and industry conversion tables consolidate these numbers for fast lookup on multi-scale gauges [7] [8].
2. What a vacuum gauge is actually showing: relative (gauge) vs absolute
Most penis-pump gauges display vacuum relative to atmospheric pressure — zero corresponds to ambient and the needle moves into negative values as pressure is reduced — so a reading of “‑5 inHg” means the device is about five inches of mercury below local atmospheric pressure, not five inches above any universal baseline [3] [9]. Converting that gauge reading into absolute units requires adding local atmospheric pressure if an absolute figure is required, but for routine pumping the gauge-relative number is the operative value users follow [2] [8].
3. Common practical conversions and an example
A common community-recommended level — about 5 inHg of vacuum — converts to roughly 127 mmHg (forum conversion noted by users) and to about 17 kPa (5 × 3.38639 kPa ≈ 16.93 kPa), so any gauge marked in inHg, mmHg or kPa can be read and converted to that same target level [4] [1]. Conversion tools and charts used by engineers and hobbyists mirror these numbers and are the right way to translate instructions that mix imperial and metric numbers [10] [7].
4. Why the unit choice doesn’t change device performance — but presentation matters
Manufacturers and community sources agree that the unit printed on the dial does not change how the pump works: units are merely different ways of expressing the same vacuum magnitude, so a kPa-marked pump is not inherently safer or more effective than an inHg-marked pump [5]. Where confusion arises is in reading the correct scale (some gauges show inner and outer rings with different units) and in remembering that the number is a negative gauge vacuum, which is why many users and technical guides recommend verifying which scale is being read on a multi-scale dial [11] [9].
5. Safety context and contested guidance
Community forums and user guides often recommend staying in modest vacuum ranges — many users advise starting around 3–5 inHg and avoiding rapid jumps to higher vacuums because of documented risks like petechiae, blistering and tissue trauma reported by peers [4] [11]. At the same time, some retail and informational pages emphasize that units do not alter device safety, implicitly shifting focus to user practices and time under vacuum rather than the unit itself [5]. Reporting here relies on available community and technical sources; medical literature on specific injury thresholds for penis-pump vacuum levels is not present in the provided reporting and therefore cannot be asserted.