Refrigerant PT Chart & Superheat / Subcooling Calculator ❄️

Convert between saturation pressure and temperature for R410A, R32, R22, R134a, R407C, R404A, R290 and R1234yf, and calculate superheat and subcooling from gauge readings. Results update as you type.

Superheat = T_{suction line} − T_{sat, dew} · Subcooling = T_{sat, bubble} − T_{liquid line}

🧮 Inputs

Refrigerant

Calculate

Temperature unit

Pressure unit

Saturation temperature (°F)

Gauge pressure (psig)

Line temperature (°F)

Measured on the suction line

Gauge pressures assume sea-level atmosphere (14.7 psi, 1.013 bar).

Result

—

Bubble (liquid)

—

Dew (vapour)

Refrigerant PT Charts

Saturation pressure in psig and bar g at each temperature. For blends with glide (R407C, R404A, R410A) the bubble (liquid) and dew (vapour) pressures are shown separately.

R410A PT Chart

HFC blend (near-azeotropic) · Split and VRF air conditioners, heat pumps · Safety class A1 · Critical temperature 71.3 °C

°F	°C	Liquid psig	Vapour psig	Liquid bar g	Vapour bar g
-40	-40.0	10.8	10.7	0.74	0.74
-35	-37.2	14.1	14.0	0.97	0.97
-30	-34.4	17.8	17.7	1.23	1.22
-25	-31.7	21.9	21.8	1.51	1.50
-20	-28.9	26.3	26.2	1.82	1.81
-15	-26.1	31.2	31.0	2.15	2.14
-10	-23.3	36.5	36.3	2.52	2.50
-5	-20.6	42.2	42.0	2.91	2.90
0	-17.8	48.4	48.2	3.34	3.33
5	-15.0	55.2	54.9	3.80	3.79
10	-12.2	62.4	62.2	4.30	4.29
15	-9.4	70.3	70.0	4.84	4.82
20	-6.7	78.7	78.4	5.42	5.40
25	-3.9	87.7	87.4	6.05	6.02
30	-1.1	97.4	97.0	6.71	6.69
35	1.7	107.7	107.3	7.43	7.40
40	4.4	118.8	118.4	8.19	8.16
45	7.2	130.6	130.1	9.00	8.97
50	10.0	143.1	142.6	9.87	9.83
55	12.8	156.5	156.0	10.79	10.75
60	15.6	170.7	170.1	11.77	11.73
65	18.3	185.8	185.2	12.81	12.77
70	21.1	201.7	201.1	13.91	13.86
75	23.9	218.6	217.9	15.07	15.03
80	26.7	236.5	235.8	16.31	16.25
85	29.4	255.4	254.6	17.61	17.55
90	32.2	275.4	274.5	18.98	18.92
95	35.0	296.4	295.4	20.43	20.37
100	37.8	318.5	317.6	21.96	21.90
105	40.6	341.9	340.9	23.57	23.50
110	43.3	366.5	365.4	25.27	25.19
115	46.1	392.3	391.2	27.05	26.97
120	48.9	419.5	418.3	28.92	28.84
125	51.7	448.1	446.9	30.89	30.81
130	54.4	478.1	476.9	32.96	32.88
135	57.2	509.6	508.4	35.13	35.05
140	60.0	542.6	541.5	37.41	37.34
145	62.8	577.4	576.4	39.81	39.74
150	65.6	613.9	613.1	42.33	42.27

R32 PT Chart

HFC (single) · New split ACs and heat pumps replacing R410A · Safety class A2L · Critical temperature 78.1 °C

°F	°C	psig	bar g
-40	-40.0	11.0	0.76
-35	-37.2	14.4	1.00
-30	-34.4	18.2	1.25
-25	-31.7	22.3	1.54
-20	-28.9	26.8	1.85
-15	-26.1	31.7	2.19
-10	-23.3	37.1	2.56
-5	-20.6	42.9	2.96
0	-17.8	49.3	3.40
5	-15.0	56.1	3.87
10	-12.2	63.5	4.38
15	-9.4	71.5	4.93
20	-6.7	80.0	5.52
25	-3.9	89.2	6.15
30	-1.1	99.1	6.83
35	1.7	109.7	7.56
40	4.4	121.0	8.34
45	7.2	133.0	9.17
50	10.0	145.8	10.06
55	12.8	159.5	11.00
60	15.6	174.1	12.00
65	18.3	189.5	13.06
70	21.1	205.8	14.19
75	23.9	223.2	15.39
80	26.7	241.5	16.65
85	29.4	260.9	17.99
90	32.2	281.3	19.40
95	35.0	302.9	20.89
100	37.8	325.7	22.46
105	40.6	349.7	24.11
110	43.3	374.9	25.85
115	46.1	401.4	27.68
120	48.9	429.4	29.60
125	51.7	458.7	31.63
130	54.4	489.5	33.75
135	57.2	521.8	35.98
140	60.0	555.8	38.32
145	62.8	591.4	40.78
150	65.6	628.8	43.36

R22 PT Chart

HCFC (single) · Older AC and chillers (phased out in most countries) · Safety class A1 · Critical temperature 96.1 °C

°F	°C	psig	bar g
-40	-40.0	0.6	0.04
-35	-37.2	2.6	0.18
-30	-34.4	4.9	0.34
-25	-31.7	7.5	0.51
-20	-28.9	10.2	0.70
-15	-26.1	13.2	0.91
-10	-23.3	16.5	1.14
-5	-20.6	20.1	1.39
0	-17.8	24.0	1.66
5	-15.0	28.3	1.95
10	-12.2	32.8	2.26
15	-9.4	37.8	2.61
20	-6.7	43.1	2.97
25	-3.9	48.8	3.37
30	-1.1	55.0	3.79
35	1.7	61.5	4.24
40	4.4	68.6	4.73
45	7.2	76.1	5.24
50	10.0	84.1	5.80
55	12.8	92.6	6.38
60	15.6	101.6	7.01
65	18.3	111.3	7.67
70	21.1	121.4	8.37
75	23.9	132.2	9.12
80	26.7	143.6	9.90
85	29.4	155.7	10.73
90	32.2	168.4	11.61
95	35.0	181.8	12.53
100	37.8	195.9	13.51
105	40.6	210.8	14.53
110	43.3	226.4	15.61
115	46.1	242.8	16.74
120	48.9	260.0	17.92
125	51.7	278.0	19.17
130	54.4	296.9	20.47
135	57.2	316.7	21.83
140	60.0	337.4	23.26
145	62.8	359.1	24.76
150	65.6	381.7	26.32

R134a PT Chart

HFC (single) · Chillers, car AC, medium-temperature refrigeration · Safety class A1 · Critical temperature 101.1 °C

°F	°C	psig	bar g
-40	-40.0	-7.3	-0.50
-35	-37.2	-6.1	-0.42
-30	-34.4	-4.8	-0.33
-25	-31.7	-3.4	-0.23
-20	-28.9	-1.8	-0.12
-15	-26.1	0.0	0.00
-10	-23.3	1.9	0.13
-5	-20.6	4.1	0.28
0	-17.8	6.5	0.45
5	-15.0	9.1	0.63
10	-12.2	11.9	0.82
15	-9.4	15.0	1.04
20	-6.7	18.4	1.27
25	-3.9	22.1	1.52
30	-1.1	26.1	1.80
35	1.7	30.4	2.10
40	4.4	35.1	2.42
45	7.2	40.1	2.76
50	10.0	45.4	3.13
55	12.8	51.2	3.53
60	15.6	57.4	3.96
65	18.3	64.0	4.42
70	21.1	71.1	4.90
75	23.9	78.7	5.42
80	26.7	86.7	5.98
85	29.4	95.2	6.57
90	32.2	104.3	7.19
95	35.0	113.9	7.86
100	37.8	124.2	8.56
105	40.6	135.0	9.31
110	43.3	146.4	10.09
115	46.1	158.4	10.92
120	48.9	171.2	11.80
125	51.7	184.6	12.73
130	54.4	198.7	13.70
135	57.2	213.6	14.73
140	60.0	229.2	15.80
145	62.8	245.7	16.94
150	65.6	262.9	18.13

R407C PT Chart

HFC blend (zeotropic, large glide) · R22 retrofit in AC and chillers · Safety class A1 · Critical temperature 86.2 °C

°F	°C	Liquid psig	Vapour psig	Liquid bar g	Vapour bar g
-40	-40.0	2.7	-2.3	0.19	-0.16
-35	-37.2	5.1	-0.4	0.35	-0.03
-30	-34.4	7.7	1.6	0.53	0.11
-25	-31.7	10.6	3.9	0.73	0.27
-20	-28.9	13.7	6.5	0.95	0.45
-15	-26.1	17.2	9.3	1.19	0.64
-10	-23.3	21.0	12.4	1.44	0.85
-5	-20.6	25.1	15.7	1.73	1.08
0	-17.8	29.5	19.4	2.03	1.34
5	-15.0	34.3	23.5	2.37	1.62
10	-12.2	39.5	27.9	2.73	1.92
15	-9.4	45.2	32.7	3.11	2.25
20	-6.7	51.2	37.9	3.53	2.61
25	-3.9	57.7	43.5	3.98	3.00
30	-1.1	64.7	49.6	4.46	3.42
35	1.7	72.2	56.1	4.98	3.87
40	4.4	80.2	63.2	5.53	4.36
45	7.2	88.8	70.7	6.12	4.88
50	10.0	97.9	78.8	6.75	5.44
55	12.8	107.6	87.5	7.42	6.03
60	15.6	118.0	96.8	8.13	6.68
65	18.3	128.9	106.7	8.89	7.36
70	21.1	140.5	117.3	9.69	8.09
75	23.9	152.8	128.5	10.54	8.86
80	26.7	165.8	140.5	11.43	9.69
85	29.4	179.6	153.2	12.38	10.56
90	32.2	194.1	166.7	13.38	11.49
95	35.0	209.4	181.0	14.44	12.48
100	37.8	225.5	196.1	15.55	13.52
105	40.6	242.4	212.1	16.71	14.63
110	43.3	260.2	229.0	17.94	15.79
115	46.1	278.9	246.9	19.23	17.02
120	48.9	298.6	265.8	20.59	18.32
125	51.7	319.2	285.7	22.01	19.70
130	54.4	340.8	306.6	23.49	21.14
135	57.2	363.3	328.8	25.05	22.67
140	60.0	387.0	352.0	26.68	24.27
145	62.8	411.7	376.6	28.39	25.97
150	65.6	437.6	402.5	30.17	27.75

R404A PT Chart

HFC blend (near-azeotropic) · Low and medium-temperature commercial refrigeration · Safety class A1 · Critical temperature 72.1 °C

°F	°C	Liquid psig	Vapour psig	Liquid bar g	Vapour bar g
-40	-40.0	4.9	4.3	0.34	0.30
-35	-37.2	7.5	6.8	0.52	0.47
-30	-34.4	10.3	9.6	0.71	0.66
-25	-31.7	13.4	12.7	0.93	0.87
-20	-28.9	16.8	16.0	1.16	1.10
-15	-26.1	20.5	19.7	1.42	1.36
-10	-23.3	24.6	23.6	1.69	1.63
-5	-20.6	28.9	27.9	1.99	1.93
0	-17.8	33.7	32.6	2.32	2.25
5	-15.0	38.8	37.7	2.67	2.60
10	-12.2	44.3	43.1	3.05	2.97
15	-9.4	50.2	49.0	3.46	3.38
20	-6.7	56.6	55.3	3.90	3.81
25	-3.9	63.4	62.1	4.37	4.28
30	-1.1	70.7	69.3	4.88	4.78
35	1.7	78.6	77.1	5.42	5.32
40	4.4	86.9	85.4	5.99	5.89
45	7.2	95.8	94.2	6.61	6.50
50	10.0	105.3	103.6	7.26	7.14
55	12.8	115.3	113.6	7.95	7.83
60	15.6	126.0	124.2	8.69	8.57
65	18.3	137.3	135.5	9.47	9.34
70	21.1	149.3	147.4	10.29	10.17
75	23.9	162.0	160.1	11.17	11.04
80	26.7	175.4	173.4	12.09	11.96
85	29.4	189.6	187.6	13.07	12.93
90	32.2	204.5	202.4	14.10	13.96
95	35.0	220.2	218.1	15.18	15.04
100	37.8	236.8	234.7	16.33	16.18
105	40.6	254.2	252.1	17.53	17.38
110	43.3	272.6	270.4	18.79	18.65
115	46.1	291.8	289.7	20.12	19.97
120	48.9	312.1	310.0	21.52	21.37
125	51.7	333.4	331.2	22.98	22.84
130	54.4	355.7	353.6	24.52	24.38
135	57.2	379.1	377.1	26.14	26.00
140	60.0	403.7	401.7	27.84	27.70
145	62.8	429.6	427.7	29.62	29.49
150	65.6	456.8	455.0	31.50	31.37

R290 PT Chart

Hydrocarbon (propane) · Small sealed refrigeration units and heat pumps · Safety class A3 · Critical temperature 96.7 °C

°F	°C	psig	bar g
-40	-40.0	1.4	0.10
-35	-37.2	3.4	0.24
-30	-34.4	5.7	0.39
-25	-31.7	8.1	0.56
-20	-28.9	10.7	0.74
-15	-26.1	13.6	0.94
-10	-23.3	16.7	1.15
-5	-20.6	20.1	1.38
0	-17.8	23.7	1.63
5	-15.0	27.6	1.90
10	-12.2	31.8	2.19
15	-9.4	36.3	2.50
20	-6.7	41.1	2.84
25	-3.9	46.3	3.19
30	-1.1	51.8	3.57
35	1.7	57.7	3.98
40	4.4	63.9	4.41
45	7.2	70.6	4.87
50	10.0	77.6	5.35
55	12.8	85.1	5.87
60	15.6	93.0	6.41
65	18.3	101.4	6.99
70	21.1	110.2	7.60
75	23.9	119.5	8.24
80	26.7	129.3	8.92
85	29.4	139.7	9.63
90	32.2	150.5	10.38
95	35.0	161.9	11.17
100	37.8	173.9	11.99
105	40.6	186.5	12.86
110	43.3	199.7	13.77
115	46.1	213.4	14.72
120	48.9	227.9	15.71
125	51.7	242.9	16.75
130	54.4	258.7	17.84
135	57.2	275.1	18.97
140	60.0	292.3	20.15
145	62.8	310.2	21.39
150	65.6	328.9	22.68

R1234yf PT Chart

HFO (single) · Car AC, low-GWP chillers · Safety class A2L · Critical temperature 94.7 °C

°F	°C	psig	bar g
-40	-40.0	-5.7	-0.39
-35	-37.2	-4.4	-0.30
-30	-34.4	-3.0	-0.20
-25	-31.7	-1.4	-0.09
-20	-28.9	0.4	0.03
-15	-26.1	2.3	0.16
-10	-23.3	4.4	0.30
-5	-20.6	6.7	0.46
0	-17.8	9.2	0.64
5	-15.0	11.9	0.82
10	-12.2	14.9	1.03
15	-9.4	18.1	1.25
20	-6.7	21.6	1.49
25	-3.9	25.4	1.75
30	-1.1	29.4	2.03
35	1.7	33.8	2.33
40	4.4	38.4	2.65
45	7.2	43.4	2.99
50	10.0	48.8	3.36
55	12.8	54.5	3.76
60	15.6	60.6	4.18
65	18.3	67.1	4.62
70	21.1	74.0	5.10
75	23.9	81.3	5.60
80	26.7	89.0	6.14
85	29.4	97.3	6.71
90	32.2	106.0	7.31
95	35.0	115.2	7.94
100	37.8	124.9	8.61
105	40.6	135.1	9.32
110	43.3	145.9	10.06
115	46.1	157.3	10.84
120	48.9	169.2	11.67
125	51.7	181.8	12.54
130	54.4	195.0	13.45
135	57.2	208.9	14.40
140	60.0	223.4	15.41
145	62.8	238.7	16.46
150	65.6	254.7	17.56

Negative psig values are vacuum (inches of mercury on a compound gauge).

How to Measure Superheat and Subcooling

Superheat: attach the low-side gauge to the suction service valve and a clamp thermometer on the suction line 15 cm (6 in) from the valve. Convert the pressure to the saturated (dew) temperature and subtract it from the line temperature.
Subcooling: attach the high-side gauge to the liquid line service valve and a clamp thermometer on the liquid line next to it. Convert the pressure to the saturated (bubble) temperature and subtract the line temperature from it.
Compare with the manufacturer's charging chart. Low superheat risks liquid floodback to the compressor; high superheat suggests undercharge or a restriction. High subcooling suggests overcharge or a liquid restriction; low subcooling suggests undercharge.

Worked example (R410A)

Suction pressure 118 psig gives a dew temperature of about 40°F. The suction line measures 52°F, so superheat = 52 − 40 = 12°F. Liquid pressure 317 psig gives a bubble temperature of about 100°F; the liquid line measures 90°F, so subcooling = 100 − 90 = 10°F.

Sizing the refrigerant lines? Use the Refrigeration Pipe Sizer. For A2L charge limits (R32, R1234yf) see the A2L Refrigerant Charge Calculator, and for the design method see Refrigerant Pipe Sizing for VRF and Split Systems.

FAQ

What is a refrigerant PT chart?

A pressure-temperature (PT) chart lists the saturation pressure of a refrigerant at each temperature. Where liquid and vapour exist together, for example inside an evaporator or condenser, the pressure fixes the temperature, so technicians use the chart to convert gauge readings into saturation temperatures.

What is the R410A pressure at 40°F?

About 118 psig (8.2 bar g). At 100°F it is about 317 psig, and at 45°F about 130 psig.

How do you calculate superheat?

Superheat = suction line temperature − saturated suction temperature. Read the suction pressure, convert it to the saturation (dew) temperature with the PT chart, then subtract that from the temperature measured on the suction line near the evaporator outlet or the outdoor unit service valve.

How do you calculate subcooling?

Subcooling = saturated condensing temperature − liquid line temperature. Read the liquid line pressure, convert it to the saturation (bubble) temperature, then subtract the temperature measured on the liquid line.

What are normal superheat and subcooling values?

Many TXV and EEV systems run about 8–12°F (4–7 K) superheat and 8–12°F (4–7 K) subcooling, while fixed-orifice systems use a target superheat from the manufacturer's charging chart. Always follow the equipment nameplate or installation manual.

Why does R407C have two pressures at one temperature?

R407C is a zeotropic blend with temperature glide. At a given pressure it starts boiling at the bubble point and finishes at a higher dew point. Use the dew point for superheat and the bubble point for subcooling.

📚 References

Saturation properties calculated with CoolProp (Bell et al., Ind. Eng. Chem. Res. 2014) using REFPROP-equivalent equations of state
ASHRAE Handbook - Fundamentals, Chapter 30: Thermophysical Properties of Refrigerants
ANSI/ASHRAE Standard 34 - Designation and Safety Classification of Refrigerants

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Refrigerant PT Chart & Superheat / Subcooling Calculator ❄️

🧮 Inputs

Refrigerant PT Charts

R410A PT Chart

R32 PT Chart

R22 PT Chart

R134a PT Chart

R407C PT Chart

R404A PT Chart

R290 PT Chart

R1234yf PT Chart

How to Measure Superheat and Subcooling

Worked example (R410A)

FAQ

📚 References

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