PhaseGauge · IAPWS‑IF97

Steam Table Calculator

Enter two properties to calculate the full thermodynamic state of water or steam. Calculations run locally in your browser.

IF97 REGION 2 Superheated vapor3.0000 MPa / 523.150 K

Computed state

Water & steam properties

Input mode: PT
Absolute pressure: 30 bar (abs)
Temperature: 250 °C
Record time: Worked example
Permalink: https://phasegauge.com/?mode=PT&p=30&pu=bar&T=250&Tu=C

Plot

Input values use their current display units. A dash means the applicable IAPWS release does not define that property for this state.
Property	Symbol	Value	Unit
State
Pressure	p	30	bar (abs)
Temperature	T	250	°C
Specific volume	v	0.0706224557	m³/kg
Density	ρ	14.1598021443	kg/m³
Vapor quality	x	—	0–1
Energy
Specific internal energy	u	2,644.6811022438	kJ/kg
Specific enthalpy	h	2,856.5484694167	kJ/kg
Specific entropy	s	6.2892866076	kJ/(kg·K)
Response
Isobaric heat capacity	cₚ	3.0772432221	kJ/(kg·K)
Isochoric heat capacity	cᵥ	2.0514286567	kJ/(kg·K)
Speed of sound	w	521.4420142599	m/s
Isobaric expansion	β	0.0032890312	1/K
Isothermal compressibility	κₜ	0.3896154582	1/MPa
Transport & electromagnetic
Dynamic viscosity	μ	17.6372247375	μPa·s
Thermal conductivity	λ	0.0463614777	W/(m·K)
Surface tension	σ	—	mN/m
Static dielectric constant	ε	1.1063236941	—
Ionization constant	pK_w	28.6955266634	—

Engineering reference

What PhaseGauge calculates

PhaseGauge uses the IAPWS Industrial Formulation 1997, the basis for industrial steam tables. It covers compressed liquid, wet steam, superheated vapor, supercritical water, and ordinary liquid water.

Calculated properties

A valid state includes pressure, temperature, specific volume, density, internal energy, enthalpy, entropy, heat capacities, speed of sound, and response coefficients. Supplemental IAPWS correlations add viscosity, thermal conductivity, surface tension, dielectric constant, and ionization constant where their validity ranges allow. A dash means the selected correlation does not define that property at the requested state.

Saturation results show the requested mixture with its liquid and vapor endpoints, plus h_fg, s_fg, and v_fg. At x = 0 or x = 1, the table shows only the requested endpoint.

Units and precision

PhaseGauge converts inputs once to MPa, K, kJ/kg, and kJ/(kg·K), then keeps the full double-precision value. Changing a unit converts the displayed input without changing the physical state. Results default to ten decimal places, with significant figures available as an optional display setting. Direct inputs stay exactly as entered in the result table.

Pressure inputs may be absolute or gauge. Barg and psig add a fixed standard atmosphere of 101.325 kPa. Use an absolute unit when a specification refers to a measured local atmosphere. JSON exports retain the full stored values.

Verification

The engine is pinned to one version and tested against official IAPWS tables for Regions 1–5, saturation equations, and backward equations. Backward checks use the absolute temperature tolerances published in each release.

The methodology page lists measured errors and source fixtures. Generated saturated and superheated steam tables use the same calculation engine.

Data in this browser

Calculations run in the page. Saved states and calculator settings stay in browser storage and are not sent to analytics. Browser storage is not an archive; Safari may clear script-written data after a period of inactivity. Export records you need to keep. CSV is intended for spreadsheets, while JSON preserves the versioned record for later import.

Practical questions

Steam calculator FAQ

Which input pairs are supported?

Choose P–T, P–h, P–s, h–s, T–h, T–s, P–x, or T–x.

What does vapor quality mean?

Quality x is the vapor mass fraction in a saturated mixture. Zero is saturated liquid, one is saturated vapor, and values between them are wet steam.

Why is a property shown as a dash?

The applicable IAPWS correlation does not define that property at the requested state. The dash distinguishes an unavailable value from zero.

Can I enter gauge pressure?

Yes. Barg and psig add a fixed standard-atmosphere reference of 101.325 kPa before calculation.

How should I cite a result?

Record the inputs, units, engine version, and access date. The print view includes this provenance, and the methodology page identifies the governing formulation.

Can I use these values in a design calculation?

Use them as property data. System assumptions, equipment limits, code requirements, and safety factors still need separate engineering review.