Measure Screw Size Online Tool

Record three things: outside thread diameter, screw length and thread pitch. Measure diameter across the widest thread crests. Measure length from the seating point to the tip, including the head for flat countersunk screws. Compare diameter with the metric or US chart, then check pitch and screw type before choosing a replacement.

Yes. Calibrate this page against a card or ruler, then manually adjust the screen gauge to the screw’s outside edges. Our tool shows approximate diameter candidates as you adjust. You can also enter measurements from a caliper. The website cannot detect a screw simply placed on the screen.

Yes. Open Measure Screw in your phone, tablet or computer browser. Calibrate the screen before adjusting the gauge, or enter measurements from a caliper. The tool cannot sense objects placed on the screen. Confirm close matches with calipers and a thread gauge.

For metric screws, measure the distance across ten thread intervals and divide by ten to estimate pitch in millimeters. For inch threads, count the thread intervals over one inch to find threads per inch, or TPI. A thread-pitch gauge is a better way to check small or closely spaced threads. Enter the pitch in the tool to compare it with the listed candidates.

Check the actual fastener rather than assuming its thread standard from your location. Measure diameter and length, then determine whether pitch is specified in millimeters or threads per inch. This tool compares common metric and US machine screw sizes; it does not include every British or specialist thread standard. Use the original specification or a supplier’s thread gauge for an uncertain match.

Measure the screw’s outside thread diameter and length, then check the wall plug manufacturer’s specified screw range. The drill diameter for the plug is a separate measurement. Suitability also depends on the wall material, plug design, fixture thickness and required embedment. The screw diameter estimate alone cannot determine a suitable plug or load rating.

A photo alone does not provide a reliable physical scale. A ruler beside the screw in the same plane can help estimate dimensions, but perspective and lens distortion can affect the result. This tool does not measure uploaded photos. Measure the physical screw with the calibrated gauge or calipers; use the example photos to compare visible screw types.

Record the outside thread diameter and length in millimeters, then measure pitch in millimeters per thread interval. For example, M4 × 0.7 means a nominal 4 mm diameter with a 0.7 mm pitch; length is recorded separately. Use the metric screw size chart to compare common sizes, and verify the pitch before replacing the screw.

Yes. Download our free screw size chart PDF for metric and US screw diameters in mm and inches, common thread pitches, screw type photos and measuring instructions. The three-page guide is a reference chart, not a life-size measuring template. Confirm thread pitch, length and application before choosing a replacement.

A machine screw size chart lists nominal thread diameter and thread spacing. In the metric chart, M4 means a nominal 4 mm diameter, and its common coarse pitch is 0.7 mm. In the US chart, #8-32 means a #8 screw with 32 threads per inch. Screw length is a separate measurement. Use our metric and US screw size charts to compare readings, then confirm pitch and length before choosing a replacement.

Measure the outside diameter across the thread crests with a caliper, or estimate it with our calibrated on-screen gauge. Record diameter and length separately in millimeters. For example, M6 indicates a nominal 6 mm thread diameter, not a 6 mm head or length. To convert a measured diameter or length from inches to mm, multiply by 25.4. The conversion does not make an inch thread compatible with a metric thread.

Measure the outside thread diameter and screw length in inches, then compare them with the US screw size chart. Smaller US machine screws use numbered sizes, such as #8 with a nominal diameter of 0.164 inches; larger sizes commonly use fractions, such as 1/4 inch. To convert millimeters to inches, divide by 25.4. Also confirm the threads per inch (TPI), because screws with the same diameter can have different thread spacing.

The screw size calculator compares your measured diameter with the nominal metric and US sizes in its reference tables and shows the closest candidates. Calibrate the screen before using the on-screen gauge, or choose Enter measurements to enter caliper readings in mm or inches. You can add thread pitch to compare common threads and select visible tip and shaft features to suggest a likely screw type. Results are estimates; the calculator does not automatically detect objects or guarantee a compatible replacement.

A #8 machine screw has a nominal outside diameter of 0.164 inches, or 4.1656 mm. Common machine threads include #8-32 UNC and #8-36 UNF. It is close in diameter to M4, but the two are not interchangeable.

M4 and M6 indicate nominal thread diameters of 4 mm and 6 mm. Common coarse pitches are 0.7 mm for M4 and 1.0 mm for M6. Length is a separate measurement, and fine-pitch variants need a separate pitch check.

There is no single drill-bit answer based only on screw diameter. Wood pilot holes, clearance holes and threaded tap holes serve different purposes. Material, screw design and thread pitch affect the correct drill size. Use the screw manufacturer's pilot-hole table or a tap-drill chart for the exact thread.

License-plate screws vary by vehicle, bracket and market. Check the vehicle manual or measure an existing screw's diameter, pitch and length. Do not force a similar-looking metric or imperial screw into the fitting.

A hole measurement alone is not enough. A clearance hole is larger than the screw, while a threaded hole has a thread profile and pitch. Identify whether it is threaded, then use suitable gauges or the original part specification.

Compare visible tip and shaft features to narrow down common screw types, including machine screws, wood screws, self-drilling screws, and possible drywall or sheet-metal screws. These are suggestions, not a confirmed identification. Check the diameter, thread pitch, head profile and intended application before selecting a replacement.