Screw Identify — Identify Screw Types and Sizes Online.
Use Screw Identify to measure an unfamiliar screw and compare its visible features with catalog candidates. Start with the tool below; calibration can help you check physical size, but you can explore without it.
A loose screw rarely arrives with a useful label. This screw identifier brings dimensions, head shapes, and recess shapes into one place so you can narrow your search. It provides identification guidance, not a guarantee that a replacement will fit. Keep the original screw and any product instructions nearby while comparing the suggestions.
How the screw identifier tool works
Measure → Describe → Compare. First, position the on-screen guides at the screw’s edges, or enter measurements you already know. The tool records total length, head length, head width, and body diameter. You can switch between metric and imperial units without starting again. Next, describe the visible head and recess shapes and the screw material. Optional details about the material it fastens into and its thread can help narrow the comparison. Exact-match choices restrict the corresponding characteristics, so check them carefully if few candidates appear. Finally, select Find Matching Screws to compare ranked catalog entries. Read the dimensions, explanations, and linked references together rather than choosing solely by the picture. Your current measurements remain available when you return to adjust them.
How to measure a screw
For a physical on-screen comparison, calibrate with a real credit card or an object of known length. A device preset supplies only a starting scale; check the reference edges and adjust them before confirming. Without valid calibration, the outline is a visual estimate, not a physical ruler. Align total length from the top of the head to the tip. Head length runs from the head’s top to its underside; head width crosses its widest part. Measure body diameter across the threaded body. This workspace uses overall length, including the head. Catalog nominal lengths often exclude a projecting head, while countersunk lengths generally include it. Check the relevant drawing before comparing a designation such as M3 × 12 with an overall measurement. Screen size, zoom, and display changes can affect the scale.
Calibrate your screenAn online screw identifier app for desktop and Android
Screw Identify is a browser-based tool, not a native Android application. Open the website in a compatible Android browser or use it on a desktop; no app-store download is required. The current identification flow is free to use, with no payment step. If you are looking for a free screw identifier app, you can begin with the measurement workspace above. A larger display may make physical comparison easier, but the controls also adapt to narrow screens. Language selection is independent of units: changing the interface language does not change your measurements. Calibration belongs to the current browser and display, so check it again when your setup changes.
Understand matches and limitations
Results are ranked catalog comparisons. A similarity score describes how closely recorded features agree; it is not the probability that a screw is correct, safe, or interchangeable. Uncalibrated measurements receive reduced confidence, and missing catalog entries cannot appear as matches. Similar-looking screws can differ in thread pitch, strength, coating, or intended use. Read the result explanations and source references, then verify the original specifications. For safety-critical applications, do not choose a replacement from an illustration or score alone. If nothing looks convincing, revisit your measurements or seek advice from the equipment manufacturer or a knowledgeable fastener supplier.
Read about accuracy and catalog dataFrequently asked questions
How to identify a screw?
Measure the overall length, head dimensions, and outside thread diameter, then compare the head shape, recess, material, and thread. Screw Identify uses these details to suggest catalog matches. Check the original specifications before selecting a replacement.
Is there an app to identify screws?
Yes. Screw Identify is a free browser-based screw identification app for compatible phones and computers. Enter measurements and visible features to compare candidates. It is not a native Android app and does not identify screws from photographs.
What are the six types of screws?
There are more than six screw types. Six examples in our chart are wood screws, machine screws, sheet-metal screws, drywall screws, socket-cap screws, and thumb screws. These are useful categories, not a complete or mutually exclusive classification.
How do I identify a screw thread?
Check the outside diameter, pitch or threads per inch (TPI), thread direction, and whether the thread is parallel or tapered. Compare these with the relevant standard. Optional thread inputs can refine catalog matching, but the tool does not certify a thread specification.
Does it provide screw specifications?
Results show recorded catalog dimensions, nominal sizes, materials, thread information where available, and source references. Coverage varies by entry. These details are identification aids, not a complete engineering specification or confirmation of strength, torque, or load capacity.
What thread is on a standard bolt?
There is no single universal standard bolt thread. Metric bolts commonly use ISO metric threads; inch fasteners may use UNC or UNF. Diameter alone cannot establish the thread. Check the diameter and pitch against the equipment specification.
Can I identify threads without a thread gauge?
You can estimate the outside diameter with calipers and the pitch with a ruler over several thread intervals. Compare both measurements with a reliable chart. Fine, worn, or damaged threads are difficult to judge; confirm uncertain measurements with a gauge or a specialist.
How do I tell the difference between UNC and UNF threads?
For the same nominal diameter, UNC is the coarse series and UNF is the fine series, with more threads per inch. For example, 1/4-20 UNC has 20 TPI; 1/4-28 UNF has 28 TPI. Measure rather than guessing by appearance.
How do I measure thread pitch without a gauge?
Measure along the screw axis across several gaps between thread crests, then divide the distance by the number of gaps. For example, 10 gaps spanning 15 mm give an estimated pitch of 1.5 mm. Eleven crests enclose 10 gaps. TPI equals 25.4 divided by pitch in millimetres.
How do I know whether this will work for my application?
Compare the original equipment specification, thread, dimensions, material, grade, coating, and operating conditions. A similarity score does not prove suitability. For structural, electrical, pressure-containing, or other safety-critical work, obtain the manufacturer's guidance or qualified advice before choosing a fastener.
Can contractors and DIY enthusiasts use this?
Yes. Contractors and DIY users can use it to narrow down unfamiliar screws and prepare questions for a supplier. It supports identification, not professional approval, building-code compliance, or engineering design.
What happens when it makes a mistake?
A suggested match may be wrong. Do not install a questionable replacement. Recheck measurements, calibration, selected features, and source specifications; consult a supplier if needed. You can report confusing or incorrect suggestions through Feedback. The tool does not automatically verify or correct a reported match.
Is it free to use?
Yes. The current Screw Identify tool is free to use. Measuring, describing, and comparing screws does not require a paid subscription.
What does it cost to try?
Trying the current identification tool costs nothing: no payment or credit-card details are required. A physical card used for screen calibration is only a size reference; the tool does not read or collect its details.
Can I use it on Android?
Yes, through a compatible mobile browser. There is no native Android app to install. Check physical calibration on the screen you are actually using.
Can I identify a screw from a photo?
No. This tool does not analyze uploaded photographs or use AI image recognition. Enter measurements and choose the visible characteristics yourself.
How accurate are on-screen measurements?
Accuracy depends on physical calibration and careful alignment. An uncalibrated outline is only an estimate. Cross-check important dimensions with a suitable measuring tool and the original specifications.
What if my screw is not in the catalog?
The catalog is limited. Check your inputs and exact-match restrictions, then consult source references or a supplier. A broader alternative is not a confirmed replacement.
Start with the screw in front of you
Measure its edges, describe what you can see, and compare the evidence. You can return to the tool without clearing your existing inputs, or revisit the measurement guide before making adjustments. Treat the suggestions as a starting point for checking the correct specification.