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ST Olaf's National School

Roll number: 19319O Balally Drive, Dundrum, Dublin 16

School details

Address: Balally Drive, Dundrum, Dublin 16 (D16E067)
Email: [email protected]
Phone: 012956513
Principal: Ger Murphy
Ethos: Catholic
DEIS: N
Irish classification: No subjects through Irish
Gaeltacht: N
Island: N
Local authority: Dun Laoghaire Rathdown
School patron: Archbishop of Dublin
School type: Ordinary
School level: All-Through School
Planning area: Goatstown_Stillorgan_DLR

Class size history

Mainstream class group data is shown separately from standard/year-group enrolment data. The source does not identify which standard/year group each class group belongs to.

Average class size

25.70

2025/26

Mainstream classes

2025/26

Largest class group

2025/26

Classes with 30+ pupils

2025/26

Class group metrics trend

Class group metrics by year

Year	Mainstream class pupils	Mainstream classes	Average class size	Largest class	Classes 30+
2006/07	345	13	26.54	33	4
2007/08	372	15	24.80	28	0
2008/09	382	15	25.47	34	1
2009/10	406	16	25.38	28	0
2010/11	412	16	25.75	28	0
2011/12	424	16	26.50	30	2
2012/13	443	16	27.69	31	6
2013/14	440	16	27.50	30	4
2014/15	444	16	27.75	31	4
2015/16	453	16	28.31	30	4
2016/17	484	17	28.47	31	4
2017/18	488	17	28.71	30	9
2019/20	509	19	26.79	30	3
2020/21	521	19	27.42	30	2
2021/22	533	20	26.65	30	2
2022/23	544	21	25.90	30	2
2023/24	574	22	26.09	32	2
2024/25	573	22	26.05	32	1
2025/26	591	23	25.70	27	0

Data highlights

Key numbers to spot outliers or notable changes.

Biggest gain in a single year: 1976/77: 355 in 1975/76 → 595, +240 pupils.
Biggest loss in a single year: 1993/94: 578 in 1983/84 → 404, -174 pupils.
Largest single-class increase: 5th Class in 2025/26 (53 → 81, +28).
Largest single-class decrease: 3rd Class in 2021/22 (81 → 58, -23).
Largest cohort-step gain: JI → SI in 2025/26 (66 → 73, +7).
Largest cohort-step loss: JI → SI in 2021/22 (79 → 76, -3).
Overall: 256 (1974/75) → 591 (2025/26), 335.

Summary statistics (class-level data)

Min / max / mean enrolment per class across the available final by-standard years.

Class	Min	Max	Mean	Years
Junior Infants	66	81	73.5	6
Senior Infants	70	80	75.3	6
1st Class	55	80	72.2	6
2nd Class	53	83	70.7	6
3rd Class	54	82	72.3	6
4th Class	54	81	68.0	6
5th Class	53	81	64.5	6
6th Class	51	78	59.5	6
Total	256	694	452.5	41

Total enrolment over time

Total and gender trends use historical records where available. Class-level data starts in 2020/21.

Enrolment by gender over time

Enrolment by class over time

Cohort progression

Base cohort:

Track how each cohort (pupils who were in the same class in the same year) progresses through the school. Each step shows the count; the number between steps is the net change (pupils gained minus pupils lost).

Cohort 2020/21

JI 2020/21 79

-3

SI 2021/22 76

-1

1st 2022/23 75

2nd 2023/24 79

3rd 2024/25 82

-1

4th 2025/26 81

Cohort 2021/22

JI 2021/22 81

-1

SI 2022/23 80

1st 2023/24 80

2nd 2024/25 83

-2

3rd 2025/26 81

Cohort 2022/23

JI 2022/23 68

SI 2023/24 70

1st 2024/25 73

2nd 2025/26 75

Cohort 2023/24

JI 2023/24 73

SI 2024/25 76

-1

1st 2025/26 75

Cohort 2024/25

JI 2024/25 66

SI 2025/26 73

Cohort 2025/26

JI 2025/26 74

Raw data by year

Year	Female	Male	JI	SI	1st	2nd	3rd	4th	5th	6th	Total
1974/75	256	–	–	–	–	–	–	–	–	–	256
1975/76	–	–	–	–	–	–	–	–	–	–	355
1976/77	382	213	–	–	–	–	–	–	–	–	595
1977/78	381	242	–	–	–	–	–	–	–	–	623
1980/81	362	332	–	–	–	–	–	–	–	–	694
1981/82	334	325	–	–	–	–	–	–	–	–	659
1982/83	300	308	–	–	–	–	–	–	–	–	608
1983/84	280	298	–	–	–	–	–	–	–	–	578
1993/94	171	233	–	–	–	–	–	–	–	–	404
1994/95	176	221	–	–	–	–	–	–	–	–	397
1995/96	180	223	–	–	–	–	–	–	–	–	403
1996/97	179	224	–	–	–	–	–	–	–	–	403
1997/98	185	219	–	–	–	–	–	–	–	–	404
1998/99	182	207	–	–	–	–	–	–	–	–	389
1999/00	164	176	–	–	–	–	–	–	–	–	340
2000/01	152	179	–	–	–	–	–	–	–	–	331
2001/02	155	175	–	–	–	–	–	–	–	–	330
2002/03	157	169	–	–	–	–	–	–	–	–	326
2003/04	137	175	–	–	–	–	–	–	–	–	312
2004/05	150	179	–	–	–	–	–	–	–	–	329
2005/06	165	177	–	–	–	–	–	–	–	–	342
2006/07	167	186	–	–	–	–	–	–	–	–	353
2007/08	181	200	–	–	–	–	–	–	–	–	381
2008/09	186	201	–	–	–	–	–	–	–	–	387
2009/10	204	211	–	–	–	–	–	–	–	–	415
2010/11	208	216	–	–	–	–	–	–	–	–	424
2011/12	207	217	–	–	–	–	–	–	–	–	424
2012/13	224	219	–	–	–	–	–	–	–	–	443
2013/14	207	233	–	–	–	–	–	–	–	–	440
2014/15	209	235	–	–	–	–	–	–	–	–	444
2015/16	221	232	–	–	–	–	–	–	–	–	453
2016/17	232	252	–	–	–	–	–	–	–	–	484
2017/18	222	266	–	–	–	–	–	–	–	–	488
2018/19	226	268	–	–	–	–	–	–	–	–	494
2019/20	229	280	–	–	–	–	–	–	–	–	509
2020/21	235	286	79	77	55	60	81	57	57	55	521
2021/22	247	286	81	76	75	53	58	78	58	54	533
2022/23	255	289	68	80	75	74	54	59	76	58	544
2023/24	264	310	73	70	80	79	78	54	62	78	574
2024/25	263	310	66	76	73	83	82	79	53	61	573
2025/26	284	307	74	73	75	75	81	81	81	51	591