ThreadCalc.com
Precision Thread Calculator
Allowance
External Dimensions
Flat At Root (Opt)
Height (Basic)
0.2500-20 UNC-2A
Major Diameter
Max
Min
Mean
Pitch Diameter
Max
Min
Tol
Minor Diameter
Max
Min (ref)
Root Radius
Max
Min
Flat At Root (Opt)
Internal Dimensions
Height (Basic)
0.2500-20 UNC-2B
Minor Diameter
Min
Max
Mean
Pitch Diameter
Min
Max
Tol
Major Diameter
Min
Max (ref)
Measurement Over Wires (3 Wire)
Max
Min
Wire Diameters
Constants
Max
Best
Best
Min
Alternate
Alternate
Reset
Thread Types and Sizes
Sizes
Unified Series 60°
Acme 29°
Buttress 7° x 45°
UNM Miniature 60°
NPT Taper Pipe 60°
NPTF Dryseal Taper Pipe 60°
NPSM Straight Pipe 60°
NPSL Straight Pipe 60°
STI Threaded Insert 60°
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ISO Series 60°
ISO Trapezoidal 30°
ISO Buttress 3° x 30°
Whitworth 55°
BA British Association 47.5°
BSPT Taper Pipe 55°
BSPP Parallel Pipe 55°
ISO Threaded Insert 60°
Pg Conduit Thread 80°
Major (Inch)
TPI
UN
UNR
UNJ
RH
LH
?
Classes of Fit
External
1A
2A
3A
Internal
1B
2B
3B
?
Starts - Pitch - Lead - Lead Angle
Starts
1
2
3
4
5
6
7
8
Pitch
Lead
Lead Angle
?
Percent Thread
Percent
100%
90%
80%
75%
70%
65%
60%
55%
50%
Minor Dia
Tap Drills
Cut Tap
Form Tap
Inch
Metric
Diameter
5.10mm
5.10mm
0.2008
7
5.11mm
0.2010
5.15mm
5.15mm
0.2028
13/64
5.16mm
0.2031
6
5.18mm
0.2040
5.20mm
5.20mm
0.2047
5
5.22mm
0.2055
5.25mm
5.25mm
0.2067
5.30mm
5.30mm
0.2087
4
5.31mm
0.2090
5.35mm
5.35mm
0.2106
5.40mm
5.40mm
0.2126
3
5.41mm
0.2130
5.45mm
5.45mm
0.2146
5.50mm
5.50mm
0.2165
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