R-134a pressure-temperature chart

Gauge pressure at sea level. R-134a is a single-component refrigerant, so liquid and vapor saturate at the same pressure. Values marked inHg are vacuum, in inches of mercury.

°F and psig°C and kPa

R-134a saturation pressure by temperature, °F and psig
°F	psig
-40	14.8 inHg
-39	14.4 inHg
-38	13.9 inHg
-37	13.4 inHg
-36	13.0 inHg
-35	12.5 inHg
-34	12.0 inHg
-33	11.4 inHg
-32	10.9 inHg
-31	10.4 inHg
-30	9.8 inHg
-29	9.3 inHg
-28	8.7 inHg
-27	8.1 inHg
-26	7.5 inHg
-25	6.9 inHg
-24	6.3 inHg
-23	5.7 inHg
-22	5.0 inHg
-21	4.3 inHg
-20	3.7 inHg
-19	3.0 inHg
-18	2.3 inHg
-17	1.5 inHg
-16	0.8 inHg
-15	0.1 inHg
-14	0.4
-13	0.7
-12	1.1
-11	1.5
-10	1.9
-9	2.4
-8	2.8
-7	3.2
-6	3.6
-5	4.1
-4	4.6
-3	5.0
-2	5.5
-1	6.0
0	6.5
1	7.0
2	7.5
3	8.0
4	8.5
5	9.1
6	9.6
7	10.2
8	10.8
9	11.3
10	11.9
11	12.5
12	13.1
13	13.8
14	14.4
15	15.0
16	15.7
17	16.4
18	17.0
19	17.7
20	18.4
21	19.1
22	19.9
23	20.6
24	21.3
25	22.1
26	22.9
27	23.7
28	24.5
29	25.3
30	26.1
31	26.9
32	27.8
33	28.6
34	29.5
35	30.4
36	31.3
37	32.2
38	33.1
39	34.1
40	35.0
41	36.0
42	37.0
43	38.0
44	39.0
45	40.1
46	41.1
47	42.2
48	43.2
49	44.3
50	45.4
51	46.6
52	47.7
53	48.9
54	50.0
55	51.2
56	52.4
57	53.6
58	54.9
59	56.1
60	57.4
61	58.7
62	60.0
63	61.3
64	62.7
65	64.0
66	65.4
67	66.8
68	68.2
69	69.7
70	71.1
71	72.6
72	74.1
73	75.6
74	77.1
75	78.7
76	80.2
77	81.8
78	83.4
79	85.0
80	86.7
81	88.4
82	90.0
83	91.8
84	93.5
85	95.2
86	97.0
87	98.8
88	100.6
89	102.5
90	104.3
91	106.2
92	108.1
93	110.0
94	112.0
95	113.9
96	115.9
97	118.0
98	120.0
99	122.1
100	124.2
101	126.3
102	128.4
103	130.6
104	132.7
105	135.0
106	137.2
107	139.5
108	141.7
109	144.0
110	146.4
111	148.7
112	151.1
113	153.5
114	156.0
115	158.4
116	160.9
117	163.4
118	166.0
119	168.6
120	171.2
121	173.8
122	176.5
123	179.1
124	181.8
125	184.6
126	187.4
127	190.1
128	193.0
129	195.8
130	198.7
131	201.6
132	204.6
133	207.5
134	210.6
135	213.6
136	216.7
137	219.7
138	222.9
139	226.0
140	229.2
141	232.4
142	235.7
143	239.0
144	242.3
145	245.7
146	249.0
147	252.5
148	255.9
149	259.4
150	262.9

R-134a saturation pressure by temperature, °C and kPa
°C	kPa
-40	-50
-39	-47
-38	-45
-37	-42
-36	-38
-35	-35
-34	-32
-33	-28
-32	-25
-31	-21
-30	-17
-29	-13
-28	-9
-27	-4
-26	0
-25	5
-24	10
-23	15
-22	20
-21	26
-20	31
-19	37
-18	43
-17	50
-16	56
-15	63
-14	69
-13	77
-12	84
-11	91
-10	99
-9	107
-8	116
-7	124
-6	133
-5	142
-4	151
-3	161
-2	171
-1	181
0	191
1	202
2	213
3	225
4	236
5	248
6	261
7	273
8	286
9	300
10	313
11	327
12	342
13	356
14	372
15	387
16	403
17	419
18	436
19	453
20	470
21	488
22	507
23	525
24	544
25	564
26	584
27	605
28	626
29	647
30	669
31	691
32	714
33	737
34	761
35	786
36	811
37	836
38	862
39	888
40	915
41	943
42	971
43	1,000
44	1,029
45	1,059
46	1,089
47	1,120
48	1,152
49	1,184
50	1,217
51	1,250
52	1,284
53	1,319
54	1,354
55	1,390
56	1,427
57	1,464
58	1,502
59	1,541
60	1,580
61	1,621
62	1,661
63	1,703
64	1,745
65	1,788

You're free to reuse this chart's numbers under CC BY 4.0. Just credit Pocket HVAC and link back to this page.

From pockethvac.com/r134a-pt-chart/. Each row is solved at its exact temperature with CoolProp 8.0.0. Free to reuse under CC BY 4.0.

What is an R-134a PT chart?

An R-134a PT chart lists the pressure R-134a boils and condenses at for each temperature. At 40°F that's just 35.0 psig, and below about -15°F it drops into a vacuum. It's a single-component refrigerant sold as Freon 134a, Forane 134a, Genetron 134a and Klea 134a.

Anywhere liquid and vapor are together in a system, like inside the evaporator and condenser coils, the pressure and temperature are locked together, so one tells you the other. On the job, the chart turns gauge readings into saturation temperatures: the suction pressure gives the temperature the evaporator is boiling at, and the liquid line pressure gives the temperature the condenser is condensing at. Compare those with your line temperatures and you have superheat and subcooling.

R-134a is a single-component refrigerant (safety class A1) that runs at much lower pressures than R-410A. In HVAC you'll mostly find it in chillers, and it was the standard refrigerant in car air conditioning for years.

How it's calculated

Absolute pressure = gauge pressure + 14.696 psi (101.325 kPa, one standard atmosphere)
Saturation data: R-134a: CoolProp 8.0.0, R134a
Between table points (every 0.5 °C): ln(pressure) is interpolated linearly in 1 ÷ absolute temperature
Printed chart rows are solved by CoolProp at each exact temperature

Sources

If a number doesn't match your chart, email me what you entered and what you expected, and I'll check it against the source. You can also read how the numbers are checked.

Checked by Paul Williams · Updated October 31, 2026

Questions

What is the R-134a pressure at 40°F?

R-134a's saturation pressure at 40°F is 35.0 psig. At 100°F it's 124.2 psig.

Why does the chart show inHg at low temperatures?

Below about -15°F, R-134a's saturation pressure is under atmospheric, so a gauge reads a vacuum. The chart shows those rows in inches of mercury, like a compound gauge.

How accurate is this chart?

It comes from the NIST equation of state for R-134a through CoolProp, and matches NIST's own tables to within 0.01 psi.

R-134a PT Chart