Dimensions, drill sizes and wrench sizes for 9/16-24 UNEF.
Designation
9/16-24 UNEF
Major (outside) diameter
14.288 mm · 0.5625"
Pitch
1.058 mm · 24 TPI
Pitch diameter
13.6 mm · 0.5354"
Minor diameter (external)
12.989 mm · 0.5114"
Minor diameter (internal)
13.142 mm · 0.5174"
Recommended tap drill
33/64" · 13.1 mm · ≈87% thread
Clearance hole
Close 37/64" · Normal 19/32" · Loose 5/8" - nominal + 1/64" / 1/32" / 1/16" to the nearest standard drill (common shop practice).
Hex head (across flats)
13/16"
Close 37/64" · Normal 19/32" · Loose 5/8" - nominal + 1/64" / 1/32" / 1/16" to the nearest standard drill (common shop practice).
9/16-24 UNEF in numbers
9/16-24 UNEF is 0.5625 in across the crests with 24 threads per inch, a 1.058 mm pitch. The basic pitch diameter is 13.6 mm and the bolt's minor diameter 12.989 mm, so the thread is 0.649 mm deep on the bolt. Its tensile stress area is 0.2139 in², 18% more than the coarser 9/16-12 UNC at the same diameter. The nearest metric size, M14 × 2.0, is 0.29 mm smaller across the crests and its pitch is 0.942 mm coarser, so the two do not interchange.
Tap drill by thread percentage
Hole = D − % × 0.0129904 × P, with D = 14.288 mm and P = 1.058 mm. A smaller hole leaves more thread; the recommended 33/64" drill above gives about 87%.
Tap-drill hole diameters for 9/16-24 UNEF at several thread percentages.
Thread
Hole (mm)
Hole (in)
Nearest drill
60%
13.46
0.5301
17/32" (0.5313 in) gives 58%
65%
13.39
0.5273
17/32" (0.5313 in) gives 58%
70%
13.33
0.5246
17/32" (0.5313 in) gives 58%
75%
13.26
0.5219
33/64" (0.5156 in) gives 87%
Tightening torque estimate
Target preload is 75% of proof load; torque is estimated from T = K · F · d.
Proof-load preload and estimated tightening torque for 9/16-24 UNEF by fastener grade or property class.
Grade / class
Stress area
Preload
Torque
SAE Grade 2
0.2139 in²
8825 lbf
83 lb·ft · 993 lb·in
SAE Grade 5
0.2139 in²
13638 lbf
128 lb·ft · 1534 lb·in
SAE Grade 8
0.2139 in²
19254 lbf
181 lb·ft · 2166 lb·in
Strengths are SAE J429 for this diameter band. J429 steps down with size: Grade 2 falls to 33 ksi proof above 3/4 in and Grade 5 to 74 ksi above 1 in, so these figures are not the small-size values. The Grade 2 row applies to bolts up to 6 in long; a longer Grade 2 bolt of the same diameter drops to 33 ksi proof.
These figures assume a nut factor of K = 0.20 (dry / as-received steel). K captures thread and head friction and can swing torque by 30% or more - a lubricated joint needs noticeably less. Change the lubrication assumption in the bolt-torque calculator.
Put 9/16-24 UNEF on a job sheet
The bolt schedule collects the fasteners for one job onto a single sheet - tap drill, wrench size, grade and tightening torque on every line, taken straight from pages like this one. Free schedules hold 3 lines and are saved in this browser only.
For a 9/16-24 UNEF thread, drill the hole with a 33/64" tap drill (13.1 mm) before tapping. That produces roughly 87% thread engagement, the usual target for a strong, tappable hole. The mating bolt has a major diameter of 14.288 mm and a pitch of 1.058 mm (24 TPI).
To pass a 9/16-24 UNEF bolt through a part rather than thread it, use a clearance hole: Close 37/64" · Normal 19/32" · Loose 5/8" - nominal + 1/64" / 1/32" / 1/16" to the nearest standard drill (common shop practice)..
All values come from the standard thread formulas (ISO 68-1 / ASME B1.1) and published standard tables. See the full reference.
Frequently asked questions
What drill size do I need to tap a 9/16-24 UNEF thread?
Drill 33/64" (13.1 mm) before tapping 9/16-24 UNEF. That leaves roughly 87% thread engagement, the usual target for a strong hole that still taps cleanly.
Is 9/16-24 UNEF a coarse or fine thread?
9/16-24 UNEF is a Unified extra-fine (UNEF) thread at 24 threads per inch, used for thin-wall parts, short thread engagement and fine adjustment.
What size clearance hole does a 9/16-24 UNEF bolt need?
Close 37/64" · Normal 19/32" · Loose 5/8" - nominal + 1/64" / 1/32" / 1/16" to the nearest standard drill (common shop practice). A clearance hole lets the 9/16-24 UNEF bolt pass through the part instead of threading into it.
How much torque should I use on a 9/16-24 UNEF bolt?
Estimated tightening torque for 9/16-24 UNEF runs from 83 lb·ft (SAE Grade 2) to 181 lb·ft (SAE Grade 8), targeting 75% of proof load with a dry nut factor of K = 0.20. Lubricated threads need noticeably less torque.
Nearest standard metric sizes by major diameter. These are substitutes by size only - the thread forms are not interchangeable, so never run one into the other.