For wood screws, inch (flat and oval head, slotted and phillips), ASME B18.6.1 is the governing document for the dimensions listed below. Mechanical and performance requirements for this part family are set by its own standards, not by the bolt and screw property-class documents.
ASME B18.6.1 — Scope
ASME B18.6.1 is "Wood screws (inch series)". An inch-series document.
Material, property class, surface finish and packaging are governed by separate documents — ISO 898-1 and ISO 898-2 for mechanical property classes, ISO 4042 for electroplated finishes.
Tolerance & Product Grades
ASME B18.6.1 does not divide wood screws, inch (flat and oval head, slotted and phillips) into product grades. Tolerances are given as limits on the individual dimensions in the table.
Where a general-tolerance class is cited on the drawing instead, it applies to the dimensions not otherwise toleranced.
Dimensions Specified by ASME B18.6.1
| Size | Type | Pitch P (in) | E (in) | F (in) | Amax (in) | Amin (in) | Head height k (in) | J (in) | T (in) | R (in) | Length range l (in) | Reference standard |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| #0 | Cross recessed oval countersunk head wood screws | 0.031 | 0.064 | 0.01 | 0.119 | 0.099 | 0.035 | 0.023 | 0.015 | 0.031 | 1/4"~1/2" | ASME B18.6.1 |
| #0 | Slotted oval countersunk head wood screws | 0.031 | 0.064 | 0.01 | 0.119 | 0.099 | 0.035 | 0.023 | 0.015 | 0.031 | 1/4"~1/2" | ASME B18.6.1 |
| #0 | Cross recessed flat countersunk head wood screws | 0.031 | 0.064 | 0.01 | 0.119 | 0.099 | 0.035 | 0.023 | 0.015 | 0.031 | 1/4"~1/2" | ASME B18.6.1 |
| #0 | Slotted flat countersunk head wood screws | 0.031 | 0.064 | 0.01 | 0.119 | 0.099 | 0.035 | 0.023 | 0.015 | 0.031 | 1/4"~1/2" | ASME B18.6.1 |
| #1 | Cross recessed oval countersunk head wood screws | 0.036 | 0.077 | 0.01 | 0.146 | 0.123 | 0.043 | 0.026 | 0.019 | 0.031 | 1/4"~1/2" | ASME B18.6.1 |
| #1 | Slotted oval countersunk head wood screws | 0.036 | 0.077 | 0.01 | 0.146 | 0.123 | 0.043 | 0.026 | 0.019 | 0.031 | 1/4"~1/2" | ASME B18.6.1 |
| #1 | Cross recessed flat countersunk head wood screws | 0.036 | 0.077 | 0.01 | 0.146 | 0.123 | 0.043 | 0.026 | 0.019 | 0.031 | 1/4"~1/2" | ASME B18.6.1 |
| #1 | Slotted flat countersunk head wood screws | 0.036 | 0.077 | 0.01 | 0.146 | 0.123 | 0.043 | 0.026 | 0.019 | 0.031 | 1/4"~1/2" | ASME B18.6.1 |
| #2 | Cross recessed oval countersunk head wood screws | 0.038 | 0.09 | 0.01 | 0.172 | 0.147 | 0.051 | 0.031 | 0.023 | 0.031 | 1/4"~1/2" | ASME B18.6.1 |
| #2 | Slotted oval countersunk head wood screws | 0.038 | 0.09 | 0.01 | 0.172 | 0.147 | 0.051 | 0.031 | 0.023 | 0.031 | 1/4"~1/2" | ASME B18.6.1 |
| #2 | Cross recessed flat countersunk head wood screws | 0.038 | 0.09 | 0.01 | 0.172 | 0.147 | 0.051 | 0.031 | 0.023 | 0.031 | 1/4"~1/2" | ASME B18.6.1 |
| #2 | Slotted flat countersunk head wood screws | 0.038 | 0.09 | 0.01 | 0.172 | 0.147 | 0.051 | 0.031 | 0.023 | 0.031 | 1/4"~1/2" | ASME B18.6.1 |
| #3 | Cross recessed oval countersunk head wood screws | 0.042 | 0.103 | 0.014 | 0.199 | 0.171 | 0.059 | 0.035 | 0.027 | 0.031 | 1/4"~5/8" | ASME B18.6.1 |
| #3 | Slotted oval countersunk head wood screws | 0.042 | 0.103 | 0.014 | 0.199 | 0.171 | 0.059 | 0.035 | 0.027 | 0.031 | 1/4"~5/8" | ASME B18.6.1 |
| #3 | Cross recessed flat countersunk head wood screws | 0.042 | 0.103 | 0.014 | 0.199 | 0.171 | 0.059 | 0.035 | 0.027 | 0.031 | 1/4"~5/8" | ASME B18.6.1 |
| #3 | Slotted flat countersunk head wood screws | 0.042 | 0.103 | 0.014 | 0.199 | 0.171 | 0.059 | 0.035 | 0.027 | 0.031 | 1/4"~5/8" | ASME B18.6.1 |
| #4 | Cross recessed oval countersunk head wood screws | 0.045 | 0.116 | 0.016 | 0.225 | 0.195 | 0.067 | 0.039 | 0.03 | 0.031 | 3/8"~1 1/2" | ASME B18.6.1 |
| #4 | Slotted oval countersunk head wood screws | 0.045 | 0.116 | 0.016 | 0.225 | 0.195 | 0.067 | 0.039 | 0.03 | 0.031 | 3/8"~1 1/2" | ASME B18.6.1 |
| #4 | Cross recessed flat countersunk head wood screws | 0.045 | 0.116 | 0.016 | 0.225 | 0.195 | 0.067 | 0.039 | 0.03 | 0.031 | 3/8"~1 1/2" | ASME B18.6.1 |
| #4 | Slotted flat countersunk head wood screws | 0.045 | 0.116 | 0.016 | 0.225 | 0.195 | 0.067 | 0.039 | 0.03 | 0.031 | 3/8"~1 1/2" | ASME B18.6.1 |
| #5 | Cross recessed oval countersunk head wood screws | 0.05 | 0.129 | 0.018 | 0.252 | 0.22 | 0.075 | 0.043 | 0.034 | 0.062 | 3/8"~1 1/2" | ASME B18.6.1 |
| #5 | Slotted oval countersunk head wood screws | 0.05 | 0.129 | 0.018 | 0.252 | 0.22 | 0.075 | 0.043 | 0.034 | 0.062 | 3/8"~1 1/2" | ASME B18.6.1 |
| #5 | Cross recessed flat countersunk head wood screws | 0.05 | 0.129 | 0.018 | 0.252 | 0.22 | 0.075 | 0.043 | 0.034 | 0.062 | 3/8"~1 1/2" | ASME B18.6.1 |
| #5 | Slotted flat countersunk head wood screws | 0.05 | 0.129 | 0.018 | 0.252 | 0.22 | 0.075 | 0.043 | 0.034 | 0.062 | 3/8"~1 1/2" | ASME B18.6.1 |
| #6 | Cross recessed oval countersunk head wood screws | 0.056 | 0.142 | 0.02 | 0.279 | 0.244 | 0.083 | 0.048 | 0.038 | 0.062 | 3/8"~2" | ASME B18.6.1 |
| #6 | Slotted oval countersunk head wood screws | 0.056 | 0.142 | 0.02 | 0.279 | 0.244 | 0.083 | 0.048 | 0.038 | 0.062 | 3/8"~2" | ASME B18.6.1 |
| #6 | Cross recessed flat countersunk head wood screws | 0.056 | 0.142 | 0.02 | 0.279 | 0.244 | 0.083 | 0.048 | 0.038 | 0.062 | 3/8"~2" | ASME B18.6.1 |
| #6 | Slotted flat countersunk head wood screws | 0.056 | 0.142 | 0.02 | 0.279 | 0.244 | 0.083 | 0.048 | 0.038 | 0.062 | 3/8"~2" | ASME B18.6.1 |
| #7 | Cross recessed oval countersunk head wood screws | 0.062 | 0.155 | 0.022 | 0.305 | 0.268 | 0.091 | 0.048 | 0.041 | 0.062 | 3/8"~2" | ASME B18.6.1 |
| #7 | Slotted oval countersunk head wood screws | 0.062 | 0.155 | 0.022 | 0.305 | 0.268 | 0.091 | 0.048 | 0.041 | 0.062 | 3/8"~2" | ASME B18.6.1 |
| #7 | Cross recessed flat countersunk head wood screws | 0.062 | 0.155 | 0.022 | 0.305 | 0.268 | 0.091 | 0.048 | 0.041 | 0.062 | 3/8"~2" | ASME B18.6.1 |
| #7 | Slotted flat countersunk head wood screws | 0.062 | 0.155 | 0.022 | 0.305 | 0.268 | 0.091 | 0.048 | 0.041 | 0.062 | 3/8"~2" | ASME B18.6.1 |
| #8 | Cross recessed oval countersunk head wood screws | 0.067 | 0.168 | 0.023 | 0.332 | 0.292 | 0.1 | 0.054 | 0.045 | 0.062 | 1/2"~3" | ASME B18.6.1 |
| #8 | Slotted oval countersunk head wood screws | 0.067 | 0.168 | 0.023 | 0.332 | 0.292 | 0.1 | 0.054 | 0.045 | 0.062 | 1/2"~3" | ASME B18.6.1 |
| #8 | Cross recessed flat countersunk head wood screws | 0.067 | 0.168 | 0.023 | 0.332 | 0.292 | 0.1 | 0.054 | 0.045 | 0.062 | 1/2"~3" | ASME B18.6.1 |
| #8 | Slotted flat countersunk head wood screws | 0.067 | 0.168 | 0.023 | 0.332 | 0.292 | 0.1 | 0.054 | 0.045 | 0.062 | 1/2"~3" | ASME B18.6.1 |
| #9 | Cross recessed oval countersunk head wood screws | 0.071 | 0.181 | 0.026 | 0.358 | 0.316 | 0.108 | 0.054 | 0.049 | 0.062 | 5/8"~3" | ASME B18.6.1 |
| #9 | Slotted oval countersunk head wood screws | 0.071 | 0.181 | 0.026 | 0.358 | 0.316 | 0.108 | 0.054 | 0.049 | 0.062 | 5/8"~3" | ASME B18.6.1 |
| #9 | Cross recessed flat countersunk head wood screws | 0.071 | 0.181 | 0.026 | 0.358 | 0.316 | 0.108 | 0.054 | 0.049 | 0.062 | 5/8"~3" | ASME B18.6.1 |
| #9 | Slotted flat countersunk head wood screws | 0.071 | 0.181 | 0.026 | 0.358 | 0.316 | 0.108 | 0.054 | 0.049 | 0.062 | 5/8"~3" | ASME B18.6.1 |
| #10 | Cross recessed oval countersunk head wood screws | 0.077 | 0.194 | 0.03 | 0.385 | 0.34 | 0.116 | 0.06 | 0.053 | 0.062 | 5/8"~3 1/2" | ASME B18.6.1 |
| #10 | Slotted oval countersunk head wood screws | 0.077 | 0.194 | 0.03 | 0.385 | 0.34 | 0.116 | 0.06 | 0.053 | 0.062 | 5/8"~3 1/2" | ASME B18.6.1 |
| #10 | Cross recessed flat countersunk head wood screws | 0.077 | 0.194 | 0.03 | 0.385 | 0.34 | 0.116 | 0.06 | 0.053 | 0.062 | 5/8"~3 1/2" | ASME B18.6.1 |
| #10 | Slotted flat countersunk head wood screws | 0.077 | 0.194 | 0.03 | 0.385 | 0.34 | 0.116 | 0.06 | 0.053 | 0.062 | 5/8"~3 1/2" | ASME B18.6.1 |
| #12 | Cross recessed oval countersunk head wood screws | 0.091 | 0.22 | 0.031 | 0.438 | 0.389 | 0.132 | 0.067 | 0.06 | 0.062 | 3/4"~3 1/2" | ASME B18.6.1 |
| #12 | Slotted oval countersunk head wood screws | 0.091 | 0.22 | 0.031 | 0.438 | 0.389 | 0.132 | 0.067 | 0.06 | 0.062 | 3/4"~3 1/2" | ASME B18.6.1 |
| #12 | Cross recessed flat countersunk head wood screws | 0.091 | 0.22 | 0.031 | 0.438 | 0.389 | 0.132 | 0.067 | 0.06 | 0.062 | 3/4"~3 1/2" | ASME B18.6.1 |
| #12 | Slotted flat countersunk head wood screws | 0.091 | 0.22 | 0.031 | 0.438 | 0.389 | 0.132 | 0.067 | 0.06 | 0.062 | 3/4"~3 1/2" | ASME B18.6.1 |
| #14 | Cross recessed oval countersunk head wood screws | 0.1 | 0.246 | 0.035 | 0.507 | 0.452 | 0.153 | 0.075 | 0.07 | 0.093 | 3/4"~4" | ASME B18.6.1 |
| #14 | Slotted oval countersunk head wood screws | 0.1 | 0.246 | 0.035 | 0.507 | 0.452 | 0.153 | 0.075 | 0.07 | 0.093 | 3/4"~4" | ASME B18.6.1 |
| #14 | Cross recessed flat countersunk head wood screws | 0.1 | 0.246 | 0.035 | 0.507 | 0.452 | 0.153 | 0.075 | 0.07 | 0.093 | 3/4"~4" | ASME B18.6.1 |
| #14 | Slotted flat countersunk head wood screws | 0.1 | 0.246 | 0.035 | 0.507 | 0.452 | 0.153 | 0.075 | 0.07 | 0.093 | 3/4"~4" | ASME B18.6.1 |
| #16 | Cross recessed oval countersunk head wood screws | 0.111 | 0.272 | 0.038 | 0.544 | 0.485 | 0.164 | 0.075 | 0.075 | 0.093 | 1 1/2"~5" | ASME B18.6.1 |
| #16 | Slotted oval countersunk head wood screws | 0.111 | 0.272 | 0.038 | 0.544 | 0.485 | 0.164 | 0.075 | 0.075 | 0.093 | 1 1/2"~5" | ASME B18.6.1 |
| #16 | Cross recessed flat countersunk head wood screws | 0.111 | 0.272 | 0.038 | 0.544 | 0.485 | 0.164 | 0.075 | 0.075 | 0.093 | 1 1/2"~5" | ASME B18.6.1 |
| #16 | Slotted flat countersunk head wood screws | 0.111 | 0.272 | 0.038 | 0.544 | 0.485 | 0.164 | 0.075 | 0.075 | 0.093 | 1 1/2"~5" | ASME B18.6.1 |
| #18 | Cross recessed oval countersunk head wood screws | 0.125 | 0.298 | 0.042 | 0.635 | 0.568 | 0.191 | 0.084 | 0.083 | 0.093 | 2 1/2"~5" | ASME B18.6.1 |
| #18 | Slotted oval countersunk head wood screws | 0.125 | 0.298 | 0.042 | 0.635 | 0.568 | 0.191 | 0.084 | 0.083 | 0.093 | 2 1/2"~5" | ASME B18.6.1 |
| #18 | Cross recessed flat countersunk head wood screws | 0.125 | 0.298 | 0.042 | 0.635 | 0.568 | 0.191 | 0.084 | 0.083 | 0.093 | 2 1/2"~5" | ASME B18.6.1 |
| #18 | Slotted flat countersunk head wood screws | 0.125 | 0.298 | 0.042 | 0.635 | 0.568 | 0.191 | 0.084 | 0.083 | 0.093 | 2 1/2"~5" | ASME B18.6.1 |
| #20 | Cross recessed oval countersunk head wood screws | 0.125 | 0.324 | 0.046 | 0.65 | 0.582 | 0.196 | 0.084 | 0.09 | 0.093 | 2"~5" | ASME B18.6.1 |
| #20 | Slotted oval countersunk head wood screws | 0.125 | 0.324 | 0.046 | 0.65 | 0.582 | 0.196 | 0.084 | 0.09 | 0.093 | 2"~5" | ASME B18.6.1 |
| #20 | Cross recessed flat countersunk head wood screws | 0.125 | 0.324 | 0.046 | 0.65 | 0.582 | 0.196 | 0.084 | 0.09 | 0.093 | 2"~5" | ASME B18.6.1 |
| #20 | Slotted flat countersunk head wood screws | 0.125 | 0.324 | 0.046 | 0.65 | 0.582 | 0.196 | 0.084 | 0.09 | 0.093 | 2"~5" | ASME B18.6.1 |
| #24 | Cross recessed oval countersunk head wood screws | 0.143 | 0.376 | 0.05 | 0.762 | 0.685 | 0.23 | 0.094 | 0.106 | 0.093 | 2"~6" | ASME B18.6.1 |
| #24 | Slotted oval countersunk head wood screws | 0.143 | 0.376 | 0.05 | 0.762 | 0.685 | 0.23 | 0.094 | 0.106 | 0.093 | 2"~6" | ASME B18.6.1 |
| #24 | Cross recessed flat countersunk head wood screws | 0.143 | 0.376 | 0.05 | 0.762 | 0.685 | 0.23 | 0.094 | 0.106 | 0.093 | 2"~6" | ASME B18.6.1 |
| #24 | Slotted flat countersunk head wood screws | 0.143 | 0.376 | 0.05 | 0.762 | 0.685 | 0.23 | 0.094 | 0.106 | 0.093 | 2"~6" | ASME B18.6.1 |
Equivalent Standards
Where direct equivalents exist (ISO ↔ DIN, ISO ↔ ASME), they are listed on the parent Wood Screws, Inch (Flat and Oval Head, Slotted and Phillips) page.
Always confirm against the dimensions on this page, since some "equivalent" standards differ in tolerances and head geometry.
When to Specify ASME B18.6.1
ASME B18.6.1 is the inch-based reference; for metric programs choose the ISO equivalent instead.
Custom manufacturing · Made to drawing
Need a screw to this standard in a non-standard size?
Parts built to ASME B18 6 1 are already in the catalog, so a special is usually a variation on existing tooling rather than a new design — which is what keeps the cost down. Made by cold heading or warm forging.
Minimum order from 2,000 pieces; samples within 7 days of drawing approval.


