Steam Properties Calculator

Look up saturated steam properties instantly — saturation temperature, latent heat, enthalpy, specific volume, and density — by pressure (psig) or temperature (°F). Full interactive reference table included.

Free Tool · BTU/lb · ft³/lb · psig ↔ °F · Full Steam Table

Lookup Mode

Find Steam Properties By

Steam Pressure

psig

Enter gauge pressure (psig). Range: 0–3,000 psig. Common plant pressures: 15, 30, 50, 100, 125, 150, 200, 300 psig.

Quick Select — Common Plant Pressures

Results update live as you type. Values interpolated from ASME steam tables.

Steam Properties

Saturation Condition

—

Enter pressure or temperature above

Saturation Temperature

—

°F

Saturation Pressure

—

psig

Latent Heat (h_fg)

—

BTU/lb

Enthalpy — Liquid (h_f)

—

BTU/lb

Enthalpy — Vapor (h_g)

—

BTU/lb

Specific Volume (v_g)

—

ft³/lb

Steam Density

—

lb/ft³

Ready Enter a pressure (psig) or temperature (°F) and click Look Up.

Full Property Summary

Conditions
Gauge pressure (psig)	—
Absolute pressure (psia)	—
Saturation temperature	—
Enthalpy
Liquid enthalpy (h_f)	—
Latent heat / evaporation (h_fg)	—
Vapor enthalpy (h_g)	—
Volume & Density
Sat. vapor specific volume (v_g)	—
Sat. liquid specific volume (v_f)	—
Steam density (1/v_g)	—
Practical Values
Steam flow for 1,000,000 BTU/hr	—
Condensate returned per 1,000 lb/hr steam	—
Boiler rating (1 BHP = 34.5 lb/hr steam)	—
Source	ASME Steam Tables (interpolated)

Steam Phase Diagram — Pressure vs. Temperature

The amber dot shows your current steam condition on the saturation curve. The blue region is two-phase (wet steam). Above the curve to the right is superheated steam. The critical point at 3,206 psia (3,191 psig) / 706°F is where liquid and vapor become indistinguishable.

Full Saturated Steam Table — Imperial Units

All values from ASME steam tables. Pressure in psig, temperature in °F, enthalpy in BTU/lb, specific volume in ft³/lb. Click any row to load those values into the calculator above.

Filter by pressure:

Pressure (psig)	Sat. Temp (°F)	Latent Heat h_fg (BTU/lb)	Liquid h_f (BTU/lb)	Vapor h_g (BTU/lb)	Spec. Volume v_g (ft³/lb)

Understanding Steam Properties

Steam tables are the fundamental reference for every boiler, heat exchanger, steam trap, and process calculation in industry. Understanding what each property means — and how they relate — is essential for sizing equipment, calculating energy balances, and troubleshooting steam system problems.

1 Latent Heat (h_fg)

The energy required to convert 1 lb of boiling water into 1 lb of steam at the same pressure, without any temperature change. This is the "working energy" of steam — the BTUs delivered to your process when steam condenses back to water.

At 0 psig (212°F): h_fg = 970 BTU/lb At 125 psig (353°F): h_fg = 868 BTU/lb At 300 psig (421°F): h_fg = 809 BTU/lb As pressure increases: → latent heat DECREASES → more energy stored as liquid heat Steam flow for Q BTU/hr: ṁ (lb/hr) = Q (BTU/hr) / h_fg (BTU/lb)

2 Enthalpy (h_f and h_g)

Total heat content above 32°F. h_f is the enthalpy of saturated liquid (hot water at boiling point). h_g is the enthalpy of saturated steam vapor. h_g = h_f + h_fg.

h_f = sensible heat of liquid (BTU/lb) h_fg = latent heat of vaporization (BTU/lb) h_g = h_f + h_fg = total steam enthalpy At 125 psig (353°F): h_f = 325 BTU/lb (liquid) h_fg = 868 BTU/lb (latent) h_g = 1,193 BTU/lb (total vapor) Heat released when steam condenses: Q = ṁ × h_fg (if all condensate leaves)

3 Specific Volume (v_g)

Volume occupied by 1 lb of saturated steam vapor. Critical for sizing steam pipes, traps, and pressure vessels. As pressure rises, steam becomes denser — v_g decreases rapidly. Low-pressure steam is much "fluffier" than high-pressure steam.

v_g = ft³ per pound of steam At 0 psig: v_g = 26.8 ft³/lb At 15 psig: v_g = 13.9 ft³/lb At 125 psig: v_g = 3.23 ft³/lb At 300 psig: v_g = 1.53 ft³/lb Pipe sizing: steam velocity 60-100 ft/s A (ft²) = ṁ × v_g / (V × 3600) where V = velocity (ft/s)

4 psig vs. psia

Gauges in the plant read psig (gauge pressure — above atmospheric). Steam tables use psia (absolute pressure). Always add 14.7 psi when looking up steam table values. This calculator handles the conversion automatically.

psia = psig + 14.7 Examples: 0 psig = 14.7 psia → 212°F 100 psig = 114.7 psia → 338°F 125 psig = 139.7 psia → 353°F 150 psig = 164.7 psia → 366°F Rule of thumb: Every ~10 psig increase above 100 psig raises sat. temperature ~3°F

Frequently Asked Questions

As pressure increases, water molecules have more kinetic energy at the boiling point, so less additional energy (latent heat) is needed to break molecular bonds and convert liquid to vapor. Meanwhile, the sensible heat (h_f) of the liquid increases with pressure. At the critical point (3,206 psia / 706°F), latent heat reaches zero — liquid and vapor become identical and there is no longer a phase change. This is why high-pressure steam systems are more efficient for heat transfer per pound of condensate removed, but less efficient per BTU of latent heat delivered.

Steam flow (lb/hr) = Heat load (BTU/hr) ÷ Latent heat h_fg (BTU/lb). For example, a heat exchanger requiring 2,000,000 BTU/hr using 125 psig steam (h_fg = 868 BTU/lb): Steam flow = 2,000,000 ÷ 868 = 2,304 lb/hr. Note this assumes all latent heat is transferred and condensate leaves the heat exchanger at saturation temperature. If subcooling occurs (condensate leaves colder than sat. temp.), additional BTUs are recovered, and slightly less steam is required.

Saturated steam is in equilibrium with liquid water at the same pressure — it exists exactly at the boiling point for that pressure. This calculator covers saturated steam. Superheated steam has been heated above the saturation temperature at the same pressure — it contains no liquid water droplets and behaves more like a gas. Superheated steam is used in turbines (less erosion, more enthalpy), while saturated steam is used for process heating (better heat transfer rate due to condensation, more predictable temperature).

One boiler horsepower (BHP) = 34.5 lb/hr of steam evaporated from water at 212°F = 33,475 BTU/hr output. This is a legacy unit still widely used in the US boiler industry. To convert your process heat load to boiler BHP: BHP = BTU/hr ÷ 33,475. For example, 3,000,000 BTU/hr ÷ 33,475 = 89.6 BHP. Always add boiler efficiency and piping losses when specifying boiler size — a rule of thumb is to add 20–25% to the calculated BHP for these losses.