Millimeter of water to Standard atmosphere 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 standard atmospheres [atm] or standard atmospheres [atm] 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] ≈ 9.678 * 10-5 standard atmospheres [atm]1 standard atmosphere [atm] ≈ 10,332.2745 millimeters of water [mmH₂O, mmWS]

Convert millimeters of water to standard atmospheres

There are two simple ways to convert millimeters of water [mmH₂O, mmWS] to standard atmospheres [atm]. In the first calculation method, the value in millimeters of water [mmH₂O, mmWS] is divided by the rounded conversion factor of 10,332.2745. The second method multiplies the value in millimeters of water [mmH₂O, mmWS] by the rounded conversion factor of 9.678 * 10-5.

  • Standard atmospheres [atm] ≈ millimeters of water [mmH₂O, mmWS] ÷ 10,332.2745
  • Standard atmospheres [atm] ≈ millimeters of water [mmH₂O, mmWS] * 9.678 * 10-5

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 standard atmospheres [atm] can be achieved using the following calculation method.

  • Standard atmospheres [atm] = millimeters of water [mmH₂O, mmWS] * 9.80665 ÷ 101,325

Convert standard atmospheres to millimeters of water

Converting standard atmospheres [atm] 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 standard atmospheres [atm] is multiplied by the rounded conversion factor of 10,332.2745. The second variant is a division. Here, the value in standard atmospheres [atm] is divided by the rounded conversion factor of 9.678 * 10-5.

  • Millimeters of water [mmH₂O, mmWS] ≈ standard atmospheres [atm] * 10,332.2745
  • Millimeters of water [mmH₂O, mmWS] ≈ standard atmospheres [atm] ÷ (9.678 * 10-5)

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

  • Millimeters of water [mmH₂O, mmWS] = standard atmospheres [atm] ÷ 9.80665 * 101,325

Converter

Decimal places

How it's calculated

Factor: 
≈ 10,332.275
Standard atmospheres = Millimeters of water * 9.80665 ÷ 101,325
Millimeters of water = Standard atmospheres ÷ 9.80665 * 101,325

To all available units

Millipascals

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