BSPP THREAD CHART DIMENSIONS

BSPP Thread Chart Dimensions Calculator to show British Standard Pipe Parallel Thread form thread dimensions where pressure-tight joints are not made on the threads. BSPP Thread Dimensions Calculator shows dimensions, tolerances and designation forfastening pipe threads for thread sizes from 1/16 to 6 according to ISO 228 - 1 standard. The thread form follows the British Standard Whitworth thread.

Some important notes from the ISO 228 - 1 standard:

- Both internal and external threads are parallel threads.

- BSPP threads are not suitable joint where pressure-tightness is made on the thread. If assemblieswith such threads must be pressure-tight, this should be made by compressing two tightening surfacesoutside the threads, and by applying an appropriate seal.

- Threads are normally of the truncated form, with crests truncated to the limits of tolerance. There is an exception to this for internal threads, where they are likely to be assembled with externalthreads in accordance with ISO 7-1 (Pipe threads where pressure-tight joints are made on the threads — Part 1: Dimensions, tolerances and designation)

- For external threads, two classes of tolerances on the pitch diameter are specified; these are Class A and Class B. The choice between class A and class B depends on the conditions of application.

- The symbol for pipe thread type is G for external and internal threads.

- Designation: Internal thread - Pipe thread ISO 228- G 1/2 , External Thread - Pipe thread 1S0 228- G 1/2 A (For tolerance Class A).

British Standard Pipe Parallel Thread (BSPP) per ISO 228-1

BSPP Thread Dimensions Chart (ISO 228-1)

Most searched sizes: 1/2, 1/4, 3/8, 1/8, 3/4, 1, 1 1/2 BSPP. Use the quick links or filter the table. For BSPT / taper threads, seeBSP Thread Chart (BSPP & BSPT).

1/8 1/4 3/8 1/2 3/4 1 1 1/2 1 1/4 5/8 Calculator

Filter sizes (examples: 1/2, 3/4, 1 1/2)

Filters the chart by the Size column.

Size	TPI (n)	Pitch P (mm)	Major Ø D (mm)	Pitch Ø D2 (mm)	Minor Ø D1 (mm)
1/16	28	0.907	7.723	7.142	6.561
1/8	28	0.907	9.728	9.147	8.566
1/4	19	1.337	13.157	12.301	11.445
3/8	19	1.337	16.662	15.806	14.95
1/2	14	1.814	20.955	19.793	18.631
5/8	14	1.814	22.911	21.749	20.587
3/4	14	1.814	26.441	25.279	24.117
7/8	14	1.814	30.201	29.039	27.877
1	11	2.309	33.249	31.77	30.291
1 1/8	11	2.309	37.897	36.418	34.939
1 1/4	11	2.309	41.91	40.431	38.952
1 1/2	11	2.309	47.803	46.324	44.845
1 3/4	11	2.309	53.746	52.267	50.788
2	11	2.309	59.614	58.135	56.656
2 1/4	11	2.309	65.71	64.231	62.752
2 1/2	11	2.309	75.184	73.705	72.226
2 3/4	11	2.309	81.534	80.055	78.576
3	11	2.309	87.884	86.405	84.926
3 1/2	11	2.309	100.33	98.851	97.372
4	11	2.309	113.03	111.551	110.072
4 1/2	11	2.309	125.73	124.251	122.772
5	11	2.309	138.43	136.951	135.472
5 1/2	11	2.309	151.13	149.651	148.172
6	11	2.309	163.83	162.351	160.872

BSPP Thread Chart Dimensions Calculator:

INPUT PARAMETERS
Pipe Thread Size

Please Wait...

RESULTS
Parameter			Value
Pipe Thread Size		-	---	---
Threads per inch		n	---
Pitch of Thread		P	---	mm
Basic Height of Thread		h	---
Height of Sharp V Thread		H	---
Major Diameter of Thread		D (= d)	---
Pitch Diameter of Thread		D₂ (= d₂)	---
Minor Diameter of Thread		D₁ (= d₁)	---
Internal Pitch Diameter	Lower Tolerance	T_D2	---
	Upper Tolerance		---
External Pitch Diameter	Lower Tolerance (Class A)	T_d2	---
	Lower Tolerance (Class B)		---
	Upper Tolerance (Class A / Class B)		---
Internal Minor Diameter	Lower Tolerance	T_D1	---
	Upper Tolerance		---
External Major Diameter	Lower Tolerance	T_d	---
	Upper Tolerance		---

FAQ: BSPP thread dimensions

What is BSPP?
BSPP is the British Standard PipeParallel thread. In ISO 228-1, the designation uses the symbolG for parallel pipe threads.

What are the dimensions for 1/2 BSPP (G 1/2) in mm?
14 TPI (pitch 1.814 mm). Major Ø 20.955 mm, pitch Ø 19.793 mm, minor Ø 18.631 mm (see the chart row for 1/2).

Do BSPP threads seal on the threads?
Typically no. BSPP joints are normally sealed by a gasket, O-ring, or another sealing surface outside the thread form.

Need BSPT (taper) dimensions?
UseBSP Thread Chart (BSPP & BSPT) for taper thread context and BSPT references.

Definitions:

BSPP Thread: British Standard Pipe Parallel Thread

BSPT Thread:British Standard Pipe Taper Thread

Supplements:

Reference

ISO 228-1 :2000 Pipe threads where pressure-tight joints are not made on the threads - Part 1: Dimensions, tolerances and designation
Oberg, E. , Jones ,F.D. , Horton H.L. , Ryffel H.H., (2016) .Machinery's Handbook . 30th edition. Industrial Press Inc.
Oberg, E. , Jones ,F.D. , Horton H.L. , Ryffel H.H., (2012) .Machinery's Handbook . 29th edition. Industrial Press Inc.