Millimeter of water to Inch of mercury Converter (and vice versa)

Created by: tinycalcs.com/en
Number of supported units: 2
Last update: 2026

This converter allows you to convert millimeters of water [mmH₂O, mmWS] to inches of mercury [inHg] or inches of mercury [inHg] to millimeters of water [mmH₂O, mmWS]. Calculations are performed in both directions. The calculation result and the entered value are displayed with up to 20 decimal places for maximum accuracy.

1 millimeter of water [mmH₂O, mmWS] ≈ 0.0029 inches of mercury [inHg]1 inch of mercury [inHg] ≈ 345.3155 millimeters of water [mmH₂O, mmWS]

Convert millimeters of water to inches of mercury

There are two simple ways to convert millimeters of water [mmH₂O, mmWS] to inches of mercury [inHg]. In the first calculation method, the value in millimeters of water [mmH₂O, mmWS] is divided by the rounded conversion factor of 345.3155. The second method multiplies the value in millimeters of water [mmH₂O, mmWS] by the rounded conversion factor of 0.0029.

  • Inches of mercury [inHg] ≈ millimeters of water [mmH₂O, mmWS] ÷ 345.3155
  • Inches of mercury [inHg] ≈ millimeters of water [mmH₂O, mmWS] * 0.0029

However, rounded conversion values are only suitable for rough conversions, as rounding errors can occur in the calculation result. The most accurate conversion of millimeters of water [mmH₂O, mmWS] to inches of mercury [inHg] can be achieved using the following calculation method.

  • Inches of mercury [inHg] = millimeters of water [mmH₂O, mmWS] * 7,453.054 ÷ 2,573,655

Convert inches of mercury to millimeters of water

Converting inches of mercury [inHg] to millimeters of water [mmH₂O, mmWS] is easy and can be done in two ways. The first method involves multiplication, in which the value in inches of mercury [inHg] is multiplied by the rounded conversion factor of 345.3155. The second variant is a division. Here, the value in inches of mercury [inHg] is divided by the rounded conversion factor of 0.0029.

  • Millimeters of water [mmH₂O, mmWS] ≈ inches of mercury [inHg] * 345.3155
  • Millimeters of water [mmH₂O, mmWS] ≈ inches of mercury [inHg] ÷ 0.0029

However, rounded conversion values do not allow for exact calculations because rounding errors can occur in the calculation result. The most accurate conversion of inches of mercury [inHg] to millimeters of water [mmH₂O, mmWS] can be achieved using the following calculation method.

  • Millimeters of water [mmH₂O, mmWS] = inches of mercury [inHg] ÷ 7,453.054 * 2,573,655

Converter

Decimal places

How it's calculated

Factor: 
≈ 345.315
Inches of mercury = Millimeters of water * 7,453.054 ÷ 2,573,655
Millimeters of water = Inches of mercury ÷ 7,453.054 * 2,573,655

To all available units

Millimeters of water

Inches of water

Millimeters of water

Kilobar

Millimeters of water

Kilograms per square centimeter

Millimeters of water

Kilograms per square meter

Millimeters of water

Kilograms per square millimeter