Upcoming Firefox release milestones

July 2026
SMTWTFS
1
153 b7 GTB
153 QA sign off
2
3
153 b8 GTB
154 build ready for QA
Final deadline for QA’s Feature Test Plan approval
4
5
6
153 b9 GTB
7
8
153 b10 GTB
9
10
153 b11 GTB
11
12
13
153 b12 GTB
14
153 release notes deadline
15
153 b13 GTB
153 go to Build
154 beta release notes ready
154 strings handed off to Engineering
16
17
154 string freeze starts
154 regression testing completed
18
19
20
Merge day
155 QA request deadline
155 a11y engineering request deadline for Nightly
Nightly 155 starts
21
153 Release
22
154 b1 GTB
23
24
154 b2 GTB
SUMO deadline
25
26
27
154 b3 GTB
28
Planned 153.0.x
29
154 b4 GTB
30
31
154 b5 GTB

August 2026
SMTWTFS
1
2
3
154 b6 GTB
4
Planned 153.0.y
155 build ready for QA
Final deadline for QA’s Feature Test Plan approval
5
154 b7 GTB
154 QA sign off
6
7
154 b8 GTB
8
9
10
154 b9 GTB
11
Planned 153.0.z
154 release notes deadline
156 QA request deadline
12
154 b10 GTB
154 go to Build
13
14
15
16
17
155 strings handed off to Engineering
155 string freeze starts
155 beta release notes ready
155 Nightly QA sign-off
18
154 Release
Merge day
156 a11y engineering request deadline for Nightly
Nightly 156 starts
19
155 b1 GTB
20
SUMO deadline
157 QA request deadline
21
155 b2 GTB
22
23
24
155 b3 GTB
25
Planned 154.0.x
26
155 b4 GTB
156 strings handed off to Engineering
156 string freeze starts
156 build ready for QA
Final deadline for QA’s Feature Test Plan approval
27
155 release notes deadline
155 go to Build
156 beta release notes ready
156 Nightly QA sign-off
Merge day
157 a11y engineering request deadline for Nightly
Nightly 157 starts
28
29
30
31
156 b1 GTB

September 2026
SMTWTFS
1
Planned 154.0.y
155 Release
2
156 b2 GTB
SUMO deadline
3
158 QA request deadline
4
156 b3 GTB
157 build ready for QA
Final deadline for QA’s Feature Test Plan approval
5
6
7
156 b4 GTB
8
Planned 154.0.z
Planned 155.0.x
9
156 b5 GTB
157 strings handed off to Engineering
157 string freeze starts
10
156 release notes deadline
156 go to Build
157 beta release notes ready
157 Nightly QA sign-off
Merge day
158 a11y engineering request deadline for Nightly
Nightly 158 starts
11
12
13
14
157 b1 GTB
15
156 Release
16
157 b2 GTB
SUMO deadline
17
159 QA request deadline
18
157 b3 GTB
158 build ready for QA
Final deadline for QA’s Feature Test Plan approval
19
20
21
157 b4 GTB
22
Planned 156.0.x
23
157 b5 GTB
158 strings handed off to Engineering
158 string freeze starts
24
157 release notes deadline
157 go to Build
158 beta release notes ready
158 Nightly QA sign-off
Merge day
159 a11y engineering request deadline for Nightly
Nightly 159 starts
25
26
27
28
158 b1 GTB
29
157 Release
30
158 b2 GTB
SUMO deadline

October 2026
SMTWTFS
1
160 QA request deadline
2
158 b3 GTB
159 build ready for QA
Final deadline for QA’s Feature Test Plan approval
3
4
5
158 b4 GTB
6
Planned 157.0.x
7
158 b5 GTB
159 strings handed off to Engineering
159 string freeze starts
8
158 release notes deadline
158 go to Build
159 beta release notes ready
159 Nightly QA sign-off
Merge day
160 a11y engineering request deadline for Nightly
Nightly 160 starts
9
10
11
12
159 b1 GTB
13
158 Release
14
159 b2 GTB
SUMO deadline
15
161 QA request deadline
16
159 b3 GTB
160 build ready for QA
Final deadline for QA’s Feature Test Plan approval
17
18
19
159 b4 GTB
20
Planned 158.0.x
21
159 b5 GTB
160 strings handed off to Engineering
160 string freeze starts
22
159 release notes deadline
159 go to Build
160 beta release notes ready
160 Nightly QA sign-off
Merge day
161 a11y engineering request deadline for Nightly
Nightly 161 starts
23
24
25
26
160 b1 GTB
27
159 Release
28
160 b2 GTB
SUMO deadline
29
162 QA request deadline
30
160 b3 GTB
161 build ready for QA
Final deadline for QA’s Feature Test Plan approval
31

November 2026
SMTWTFS
1
2
160 b4 GTB
3
Planned 159.0.x
4
160 b5 GTB
161 strings handed off to Engineering
161 string freeze starts
5
160 release notes deadline
160 go to Build
161 beta release notes ready
161 Nightly QA sign-off
Merge day
162 a11y engineering request deadline for Nightly
Nightly 162 starts
6
7
8
9
161 b1 GTB
10
160 Release
11
161 b2 GTB
SUMO deadline
12
163 QA request deadline
13
161 b3 GTB
162 build ready for QA
Final deadline for QA’s Feature Test Plan approval
14
15
16
161 b4 GTB
17
Planned 160.0.x
18
161 b5 GTB
162 strings handed off to Engineering
162 string freeze starts
19
161 release notes deadline
161 go to Build
162 beta release notes ready
162 Nightly QA sign-off
Merge day
163 a11y engineering request deadline for Nightly
Nightly 163 starts
20
21
22
23
162 b1 GTB
24
161 Release
25
162 b2 GTB
SUMO deadline
26
164 QA request deadline
27
162 b3 GTB
163 build ready for QA
Final deadline for QA’s Feature Test Plan approval
28
29
30
162 b4 GTB

December 2026
SMTWTFS
1
Planned 161.0.x
2
162 b5 GTB
163 strings handed off to Engineering
163 string freeze starts
3
162 release notes deadline
162 go to Build
163 beta release notes ready
163 Nightly QA sign-off
Merge day
164 a11y engineering request deadline for Nightly
Nightly 164 starts
4
5
6
7
163 b1 GTB
8
162 Release
9
163 b2 GTB
10
SUMO deadline
11
163 b3 GTB
164 build ready for QA
Final deadline for QA’s Feature Test Plan approval
12
13
14
163 b4 GTB
15
Planned 162.0.x
16
163 b5 GTB
17
18
163 b6 GTB
19
20
21
163 b7 GTB
22
23
24
25
26
27
28
29
30
31

January 2027
SMTWTFS
1
2
3
4
163 b8 GTB
5
6
164 strings handed off to Engineering
164 string freeze starts
7
163 release notes deadline
163 go to Build
164 beta release notes ready
164 Nightly QA sign-off
Merge day
8
9
10
11
164 b1 GTB
12
163 Release
13
164 b2 GTB
SUMO deadline
14
15
164 b3 GTB
16
17
18
164 b4 GTB
19
Planned 163.0.x
20
164 b5 GTB
21
164 release notes deadline
164 go to Build
22
23
24
25
26
164 Release
27
28
29
30
31