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Water & steam

Water & steam (IAPWS) · H2O

Water and steam (H₂O, CAS 7732-18-5) from the IAPWS-95 reference formulation: this page gives the saturation table — pressure, saturated liquid and vapour density, enthalpy and the latent heat — from 0 to 370 °C, and a superheated-steam grid of density, enthalpy and entropy from 1 to 200 bar (absolute) and 100 to 600 °C.

Values are computed from CoolProp==6.6.0 - reference Helmholtz equation of state for Water (IAPWS-95; Wagner & Pruss, 2002). The saturation table runs 0370 °C; the superheated grid covers 1200 bar (absolute) and 100600 °C.

Also known as
water, steam, H2O, dihydrogen monoxide
CAS number
7732-18-5
Critical point
373.946 °C · 22064 kPa
Identity & datum
Molar mass
18.0153g/mol
Critical temperature
373.946°C
Critical pressure
22064kPa
Triple point
0.01°C

Enthalpy and entropy follow the IAPWS reference-state convention: internal energy and entropy are zero for saturated liquid at the triple point (0.01 degC). Enthalpy and entropy values from a table built on a different reference state are not directly comparable to these.

NIST Chemistry WebBook, SRD 69 - Thermophysical Properties of Fluid Systems. NIST Chemistry WebBook, SRD 69, Thermophysical Properties of Fluid Systems, water (H2O, CAS 7732-18-5): molar mass and critical point. https://webbook.nist.gov/cgi/fluid.cgi?ID=C7732185&Action=Page

Saturation at 100 °C
reference snapshot
Saturation pressure
1.014bar
Liquid density
958.4kg/m³
Vapour density
0.5982kg/m³
Latent heat h_fg
2256kJ/kg
Liquid entropy s_f
1.3072kJ/kg·K
Explore

Read a value on the saturation line or in superheat

The saturation mode inverts the committed saturation line by temperature or pressure; the superheated mode interpolates the committed pressure × temperature grid for density, enthalpy and entropy. Inputs stay within the validated ranges and are never extrapolated, and nothing is computed from an equation of state in your browser.

Interpolated along the tabulated saturation line — temperature 0–370 °C, never extrapolated.

100 °C
Saturation temp
100.0 °C
Saturation pressure
1.0142 bar
Pressure
101.42 kPa
Gauge pressure
0.0 psig
Liquid density
958.4 kg/m³
Vapour density
0.5982 kg/m³
Latent heat h_fg
2256.4 kJ/kg
Liquid enthalpy h_f
419.2 kJ/kg
Vapour enthalpy h_g
2675.6 kJ/kg
Liquid entropy s_f
1.3072 kJ/kg·K

The saturation line is the pressure–temperature pair at which water boils and steam condenses. Reading by pressure inverts the same committed line, so the temperature and every column stay consistent. Enthalpy and entropy use the IAPWS reference state.

Saturation table

Water along the saturation line

Rows are temperature (°C). Saturation pressure is shown in kPa, bar and gauge psig (psig is negative below 100 °C, a partial vacuum); ρ_liq and ρ_vap are the saturated liquid and vapour density (kg/m³); h_f, h_g and h_fg are the saturated liquid, saturated vapour and latent-heat enthalpy (kJ/kg); s_f and s_g are the saturated liquid and vapour entropy (kJ/kg·K), all on the IAPWS reference state.

°Cp (kPa)p (bar)p (psig)ρ_liqρ_vaph_fh_gh_fgs_fs_g
00.610.0061−14.6999.790.0049-0.02500.92500.9-0.00019.1558
50.870.0087−14.6999.920.006821.02510.12489.00.07629.0248
101.230.0123−14.5999.650.009442.02519.22477.20.15118.8998
151.710.0171−14.4999.060.012863.02528.32465.40.22458.7803
202.340.0234−14.4998.160.017383.92537.42453.50.29658.6660
253.170.0317−14.2997.000.0231104.82546.52441.70.36728.5566
304.250.0425−14.1995.610.0304125.72555.52429.80.43688.4520
355.630.0563−13.9993.990.0397146.62564.52417.90.50518.3517
407.380.0738−13.6992.180.0512167.52573.52406.00.57248.2555
459.590.0959−13.3990.170.0656188.42582.42394.00.63868.1633
5012.350.1235−12.9988.000.0832209.32591.32381.90.70388.0748
5515.760.1576−12.4985.660.1046230.32600.12369.80.76807.9898
6019.950.1995−11.8983.160.1304251.22608.82357.70.83137.9082
6525.040.2504−11.1980.520.1615272.12617.52345.40.89377.8296
7031.200.3120−10.2977.730.1984293.12626.12333.00.95517.7540
7538.600.3860−9.1974.810.2422314.02634.62320.61.01587.6812
8047.410.4741−7.8971.770.2937335.02643.02308.01.07567.6110
8557.870.5787−6.3968.590.3539356.02651.32295.31.13467.5434
9070.180.7018−4.5965.300.4239377.02659.52282.51.19297.4781
9584.610.8461−2.4961.880.5049398.12667.62269.51.25047.4151
100101.421.01420.0958.350.5982419.22675.62256.41.30727.3541
Show 110370 °C (27 more rows)
°Cp (kPa)p (bar)p (psig)ρ_liqρ_vaph_fh_gh_fgs_fs_g
110143.381.43386.1950.950.8269461.42691.12229.61.41887.2381
120198.671.986714.1943.111.1221503.82705.92202.11.52797.1291
130270.282.702824.5934.831.4970546.42720.12173.71.63467.0264
140361.543.615437.7926.131.9667589.22733.42144.31.73926.9293
150476.164.761654.4917.012.5481632.22745.92113.71.84186.8371
160618.236.182375.0907.453.2596675.52757.42082.01.94266.7491
170792.197.9219100.2897.454.1222719.12767.92048.82.04176.6650
1801002.8110.0281130.7887.005.1588763.12777.22014.22.13936.5841
1901255.2412.5524167.4876.086.3954807.42785.31977.92.23556.5059
2001554.9315.5493210.8864.667.8610852.32792.01939.72.33056.4302
2101907.6719.0767262.0852.729.5885897.62797.31899.62.42456.3563
2202319.5923.1959321.7840.2211.6154943.62800.91857.42.51776.2840
2302797.0927.9709391.0827.1213.9853990.22802.91812.72.61016.2128
2403346.9333.4693470.7813.3716.74901037.62803.01765.42.70206.1423
2503976.1739.7617562.0798.8919.96681085.82800.91715.22.79356.0721
2604692.2646.9226665.9783.6323.71171135.02796.61661.62.88496.0016
2705502.9955.0299783.4767.4628.07331185.32789.71604.42.97655.9304
2806416.5864.1658916.0750.2833.16471236.92779.91543.03.06855.8579
2907441.7874.41781064.6731.9139.13151290.02766.71476.73.16125.7834
3008587.9085.87901230.9712.1446.16791345.02749.61404.63.25525.7059
3109865.0598.65051416.1690.6754.54141402.22727.91325.73.35105.6244
32011284.29112.84291622.0667.0964.63841462.22700.61238.43.44945.5372
33012858.05128.58051850.2640.7777.05041525.92666.01140.23.55185.4421
34014600.68146.00682103.0610.6792.75881594.52621.81027.33.66015.3356
35016529.42165.29422382.7574.71113.60561670.92563.6892.73.77845.2110
36018666.01186.66012692.6527.59143.89841761.72481.5719.83.91675.0536
37021043.56210.43563037.4451.43201.83931890.72334.5443.84.11124.8012
Superheated grid

Superheated steam, pressure × temperature

Rows are temperature (°C); columns are pressure (bar absolute). In the superheated grid, a cell is left blank where the temperature is at or below the saturation temperature at that pressure - the state there is saturated or liquid water, not superheated steam - and the explorer will not interpolate across such a cell. For example, at 10 bar water is not superheated below 179.9 degC.

Superheated Density kg/m³
°C \ bar1251020406080100150200
1000.5897
1500.51641.0418
2000.46030.92552.35284.8539
2500.41560.83412.10784.29658.9689
3000.37900.75971.91353.87627.967716.9927.6341.19
3500.34830.69791.75393.53987.215015.0423.6733.3644.5687.10
4000.32230.64541.61993.26156.613113.6221.0929.1237.8363.81100.5
4500.29990.60041.50563.02626.114612.4919.1726.1833.5854.1278.61
5000.28050.56141.40662.82405.692111.5717.6523.9430.4848.0167.60
5500.26340.52711.32002.64795.327810.7916.3922.1428.0543.5860.35
6000.24830.49681.24362.49315.009710.1215.3220.6326.0640.1354.99
Superheated Enthalpy kJ/kg
°C \ bar1251020406080100150200
1002675.8
1502776.62769.1
2002875.52870.72855.82828.3
2502974.52971.22961.02943.12903.2
3003074.53072.13064.63051.63024.22961.72885.52786.5
3503175.83173.93168.13158.23137.73093.33043.92988.12924.02693.1
4003278.63277.03272.33264.53248.33214.53178.23139.43097.42975.72816.9
4503382.83381.63377.73371.33358.23331.23302.93273.33242.33157.93061.7
5003488.73487.73484.53479.13468.23446.03423.13399.53375.13310.83241.2
5503596.33595.43592.73588.13579.03560.33541.33521.83502.03450.43396.1
6003705.63704.83702.53698.63690.73674.93658.73642.43625.83583.13539.0
Superheated Entropy kJ/kg·K
°C \ bar1251020406080100150200
1007.3610
1507.61477.2810
2007.83567.50817.06106.6955
2508.03467.71007.27246.92656.5475
3008.21727.89417.46147.12466.76846.36396.07035.7937
3508.38668.06447.63467.30296.95836.58436.33576.13215.94595.4437
4008.54518.22357.79557.46697.12926.77146.54326.36586.21415.88195.5526
4508.69468.37347.94657.62007.28666.93866.72196.55796.42196.14345.9043
5008.83618.51528.08927.76417.43377.09226.88266.72666.59956.34806.1446
5508.97108.65028.22497.90087.57257.23557.03076.87996.75856.52306.3389
6009.09988.77928.35438.03107.70437.37057.16937.02216.90456.67966.5075
Typical values

What the saturation line says at a glance

At 10 bar (1000 kPa), water boils at about 179.9 °C, with a latent heat of vaporisation of about 2015 kJ/kg. At 100 °C, the saturation pressure is 1.01 bar (101 kPa) and the latent heat is 2256 kJ/kg. At 200 °C, the saturation pressure is 15.55 bar (1555 kPa) and the latent heat is 1940 kJ/kg.

Sources

Where the numbers come from

Every value on this page is computed by a deterministic equation of state — none is entered by hand. The generating method and the references it is checked against:

  • NIST Chemistry WebBook, SRD 69 - Thermophysical Properties of Fluid Systems (IAPWS-95-based saturation and isobaric tables), water (CAS 7732-18-5)
  • IAPWS R7-97(2012) - Revised Release on the IAPWS Industrial Formulation 1997 for the Thermodynamic Properties of Water and Steam (IF97 computer-program verification values)
  • CoolProp 6.6.0 - reference Helmholtz equation of state for Water (IAPWS-95; Wagner & Pruss, 2002)

Model: CoolProp==6.6.0 - reference Helmholtz equation of state for Water (IAPWS-95; Wagner & Pruss, 2002) · Generated 2026-06-07

The committed data file for this page is published as JSON on GitHub under CC BY 4.0.

Validation

Checked against cited values

The formulation is cross-checked against the IAPWS-IF97 published verification values (the industrial-formulation release document, tolerance 0.2% to absorb the IF97-vs-IAPWS-95 formulation difference) and against NIST WebBook saturation and isobaric points. Points flagged same-lineage share the IAPWS-95 formulation with the model, so they are a provenance check rather than an independent measurement. The page is published only because every check passes.

Property / pointSaturation pressure · 226.85 °C
Cited reference value2638.89776 kPa
Model computed2639.196 kPa
Error vs reference0.0113% (tolerance 0.2%)

IAPWS R7-97(2012) - Revised Release on the IAPWS Industrial Formulation 1997 for the Thermodynamic Properties of Water and Steam. IAPWS R7-97(2012), Industrial Formulation 1997 (IF97), saturation-pressure equation (Region 4), verification value: at T = 500 K (226.85 degC) the saturation pressure ps = 2.63889776 MPa. IF97 and IAPWS-95 agree to within ~0.05% over this range; the 0.2% tolerance absorbs the formulation difference. http://www.iapws.org/relguide/IF97-Rev.html

Property / pointSaturated-liquid density · 100 °C
Cited reference value958.35 kg/m3
Model computed958.3491 kg/m3
Error vs reference0.0001% (tolerance 0.1%)

Same-lineage provenance check (IAPWS-95 both sides). NIST Chemistry WebBook, SRD 69 - Thermophysical Properties of Fluid Systems. NIST Chemistry WebBook, SRD 69, Thermophysical Properties of Fluid Systems, water (H2O, CAS 7732-18-5), saturation table at 100 degC: saturated-liquid density = 958.35 kg/m3. Same-lineage provenance check (NIST SRD 69 and CoolProp both use IAPWS-95). https://webbook.nist.gov/cgi/fluid.cgi?ID=C7732185&Action=Page

Property / pointLatent heat of vaporisation · 100 °C
Cited reference value2256.4 kJ/kg
Model computed2256.4037 kJ/kg
Error vs reference0.0002% (tolerance 0.1%)

Same-lineage provenance check (IAPWS-95 both sides). NIST Chemistry WebBook, SRD 69 - Thermophysical Properties of Fluid Systems. NIST Chemistry WebBook, SRD 69, Thermophysical Properties of Fluid Systems, water (H2O, CAS 7732-18-5), saturation table at 100 degC: enthalpy of vaporisation h_fg = h_g - h_f = 2675.6 - 419.17 = 2256.4 kJ/kg. Same-lineage provenance check (NIST SRD 69 and CoolProp both use IAPWS-95). https://webbook.nist.gov/cgi/fluid.cgi?ID=C7732185&Action=Page

Property / pointSaturated-liquid entropy · 100 °C
Cited reference value1.3072 kJ/kg.K
Model computed1.307211 kJ/kg.K
Error vs reference0.0009% (tolerance 0.1%)

Same-lineage provenance check (IAPWS-95 both sides). NIST Chemistry WebBook, SRD 69 - Thermophysical Properties of Fluid Systems. NIST Chemistry WebBook, SRD 69, Thermophysical Properties of Fluid Systems, water (H2O, CAS 7732-18-5), saturation table at 100 degC: saturated-liquid entropy s_f = 1.3072 kJ/kg.K (IAPWS reference state). Same-lineage provenance check (NIST SRD 69 and CoolProp both use IAPWS-95). https://webbook.nist.gov/cgi/fluid.cgi?ID=C7732185&Action=Page

Property / pointSuperheated-steam enthalpy · 10 bar · 300 °C
Cited reference value3051.6 kJ/kg
Model computed3051.6324 kJ/kg
Error vs reference0.0011% (tolerance 0.1%)

Same-lineage provenance check (IAPWS-95 both sides). NIST Chemistry WebBook, SRD 69 - Thermophysical Properties of Fluid Systems. NIST Chemistry WebBook, SRD 69, Thermophysical Properties of Fluid Systems, water (H2O, CAS 7732-18-5), isobaric table at 1.0 MPa (10 bar): specific enthalpy at 300 degC = 3051.6 kJ/kg (IAPWS reference state). Same-lineage provenance check (NIST SRD 69 and CoolProp both use IAPWS-95). https://webbook.nist.gov/cgi/fluid.cgi?ID=C7732185&Action=Page

Property / pointSuperheated-steam density · 100 bar · 500 °C
Cited reference value30.48 kg/m3
Model computed30.4779 kg/m3
Error vs reference0.007% (tolerance 0.1%)

Same-lineage provenance check (IAPWS-95 both sides). NIST Chemistry WebBook, SRD 69 - Thermophysical Properties of Fluid Systems. NIST Chemistry WebBook, SRD 69, Thermophysical Properties of Fluid Systems, water (H2O, CAS 7732-18-5), isobaric table at 10 MPa (100 bar): density at 500 degC = 30.48 kg/m3 (specific volume 0.032811 m3/kg). Same-lineage provenance check (NIST SRD 69 and CoolProp both use IAPWS-95). https://webbook.nist.gov/cgi/fluid.cgi?ID=C7732185&Action=Page

Limitations

Before you use these numbers

  • CoolProp reference Helmholtz equation of state (IAPWS-95; Wagner & Pruss, 2002) for water and steam. The saturation table runs from 0 to 370 degC; the critical point is 373.946 degC / 22064 kPa, above the table top, so every saturation row is sub-critical. The superheated grid covers 1 to 200 bar (absolute) and 100 to 600 degC. The correlation is not extrapolated beyond the tabulated ranges. Values are for preliminary design; verify for critical service.
  • Enthalpy and entropy follow the IAPWS reference-state convention: internal energy and entropy are zero for saturated liquid at the triple point (0.01 degC). Enthalpy and entropy values from a table built on a different reference state are not directly comparable to these.
  • In the superheated grid, a cell is left blank where the temperature is at or below the saturation temperature at that pressure - the state there is saturated or liquid water, not superheated steam - and the explorer will not interpolate across such a cell. For example, at 10 bar water is not superheated below 179.9 degC.
  • Use for preliminary design; verify for critical service.
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