How to Measure a Lag Screw
Lag screws are measured like other protruding-head fasteners: from the bearing surface under the head to

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QUICK RULE
Lag screws are measured like other protruding-head
fasteners: from the bearing surface under the head to
the point/end.
LENGTH
to the tip of the point
LENGTH: underside of hex head -> tip/end.
DIAMETER: nominal body/thread diameter.
Measure thread length separately when it matters; many lag screws are not fully threaded.
Record head style, point style, material and finish.
Pilot-hole selection depends on wood species, diameter and application - it is not the same
as measuring the lag screw.
IDENTIFICATION ORDER
Product -> diameter -> thread -> length -> head/drive -> grade/material -> finish -> governing specification
REFERENCE ONLY. Verify the current ASME/SAE/ASTM/ISO/OEM standard and manufacturer data. Do not use as the sole basis for critical fastener selection or installation.
Fastener Guide reference FG-6FF0A6 · thefastenerapp.com/fastener-guide/measure-and-identify/how-to-measure-a-lag-screw · © The Fastener App. Reference only — verify the current governing standard, drawing and manufacturer data before specifying or installing.

























