--- title: "How long does hair need to be for drug test" description: "How long does hair need to be for drug test? Hair drug tests require 1.5 inches of hair for reliable detection. Call (877) 731-6362 for testing details." author: "AMH Nationwide" date: "2026-08-28" tags: ["how long does hair need to be for drug test"] canonical: "https://amhnationwide.com/how-long-does-hair-need-to-be-for-drug-test/" last_updated: "2026-08-28" --- # How long does hair need to be for drug test **By AMH Nationwide** | August 28, 2026 How long does hair need to be for drug test? Hair drug tests require 1.5 inches of hair for reliable detection. Call (877) 731-6362 for testing details. --- How long does hair need to be for drug test? Typically, a minimum of 1.5 inches of head hair is required to perform a standard hair drug test, allowing detection of drug use over approximately 90 days. Hair drug testing offers a longer detection window than urine tests. Call (877) 731-6362 to schedule a test. HAIR LENGTH REQUIREMENTS ## How long does hair need to be for drug test to ensure accurate results? The standard hair length required for a hair drug test is at least 1.5 inches (approximately 3.8 cm) from the scalp. This length allows laboratories to analyze roughly 90 days of hair growth, as hair grows about half an inch per month. If head hair is shorter than 1.5 inches, body hair may be used, but it provides a less precise [detection window](https://amhnationwide.com/hair-follicle-drug-test-detection-window/) and may complicate interpretation. DETECTION WINDOW ## What detection window does 1.5 inches of hair provide in drug testing? A 1.5-inch hair sample corresponds to approximately 90 days of drug use history. Hair testing can detect drug metabolites deposited in hair shafts during this period, making it useful for identifying long-term patterns of substance use. This detection window is significantly longer than [urine](https://amhnationwide.com/urine-drug-testing/) or saliva tests, which typically detect recent use within days. Hair length: 1.5 inches Detection window: Up to 90 days Growth rate: ~0.5 inch per month LAB COLLECTION PROCESS ## How is hair collected and processed for drug testing? Hair collection is performed at one of AMH Nationwide’s 20,000+ collection sites nationwide. A small sample of hair is cut close to the scalp, usually from the crown area to ensure recent growth is tested. Samples are sent to one of five national lab networks: [Quest Diagnostics](https://www.questdiagnostics.com/), [LabCorp](https://www.labcorp.com/), Omega Labs, United States Drug Testing Labs, or ExperTox. Each lab follows strict protocols aligned with [SAMHSA](https://www.samhsa.gov/workplace/drug-testing) and CAP standards. Every non-negative result undergoes review by a certified Medical Review Officer (MRO) to confirm findings and address any medical explanations. TESTING REGULATIONS ## Are hair drug tests regulated differently for DOT safety-sensitive roles? DOT-regulated drug testing for safety-sensitive employees requires urine testing using the federally certified [49 CFR Part 40](https://www.transportation.gov/odapc/part40) protocol. Hair testing is permitted only for non-DOT roles. AMH Nationwide provides hair drug testing for employers, courts, [probation](https://amhnationwide.com/hair-follicle-drug-test-probation/) officers, and individuals where non-DOT testing is appropriate, ensuring compliance with relevant regulations. ## Schedule Your Hair Drug Test Today Call (877) 731-6362 to locate a nearby collection site and arrange hair drug testing with AMH Nationwide. Expert lab networks and certified Medical Review Officers ensure accurate results. [Call (877) 731-6362](tel:+18777316362)[Contact Us](https://amhnationwide.com/contact-us/) LIMITATIONS AND CONSIDERATIONS ## Can hair length or other factors affect the reliability of hair drug tests? Hair length shorter than 1.5 inches may limit the detection window or require body hair, which is less reliable due to variable growth rates. Hair treatments like bleaching or dyeing can potentially affect test sensitivity but do not prevent detection. Passive exposure to drugs is unlikely to cause a positive result due to the nature of drug incorporation into hair. Hair testing does not detect very recent drug use within the past week since it takes time for metabolites to incorporate into hair shafts. PRICING AND ORDERING ## How do I arrange a hair drug test and what affects pricing? AMH Nationwide does not offer online ordering. To arrange hair drug testing, call (877) 731-6362 to be directed to a local collection site. Pricing varies depending on the specific drug panel and detection window required. Contact us for a detailed quote based on your testing needs. AMH Reviewed & Maintained By AMH Nationwide Customer Service AMH Nationwide is BBB A+ accredited and routes every order through Quest Diagnostics, LabCorp, Omega Labs, United States Drug Testing Labs, or ExperTox, all of which use multiple lab certification agencies and standards such as SAMHSA-aligned laboratory protocols, the ANSI National Accreditation Board for forensic testing and calibration, the College of American Pathologists (CAP), and Clinical Laboratory Improvement Amendments (CLIA). Every non-negative screen is reviewed by a certified Medical Review Officer as part of standard processing before a result is released, and chain-of-custody documentation is maintained on every collection. This page does not constitute medical or legal advice. **Last updated:** July 2026 You May Also Need [Nail Drug TestingNo head or body hair available? A 5-panel fingernail test covers a similar look-back window.Learn more →](https://amhnationwide.com/5-panel-fingernail-drug-test/)[ChildGuard: Environmental ExposureConcerned about a child or loved one? ChildGuard screens for exposure to drugs in their environment.Learn more →](https://amhnationwide.com/5-panel-hair-drug-test-environmental-exposure-childguard/)[Shorten the Detection WindowShortened options like 30 and 60 day hair panels are also available, useful when a urine test’s 1-3 day window is too short.Learn more →](https://amhnationwide.com/30-day-hair-drug-test/)[Hair ETG Alcohol TestAlso need alcohol testing? The hair ETG test screens for alcohol use, and can be added to the same collection.Learn more →](https://amhnationwide.com/etg-and-peth/) Frequently Asked Questions ## Common Questions The minimum hair length required is 1.5 inches from the scalp. This length provides about 90 days of drug use history for testing. Yes, body hair can be used if head hair is too short. However, body hair has variable growth rates and provides a less precise detection window. Drugs typically appear in hair samples about 5-7 days after use, as hair needs to grow out from the scalp incorporating drug metabolites. Hair treatments like bleaching or dyeing may reduce drug metabolite levels but generally do not prevent detection in a hair drug test. No, DOT-regulated safety-sensitive testing requires urine tests under 49 CFR Part 40. Hair testing is used for non-DOT roles. Call (877) 731-6362 to be directed to a nearby collection site. AMH does not offer online ordering. Sources • [SAMHSA – Mandatory Guidelines for Federal Workplace Drug Testing Programs](https://www.samhsa.gov/workplace/drug-testing) • [U.S. DOT – 49 CFR Part 40 – Procedures for Transportation Workplace Drug and Alcohol Testing Programs](https://www.transportation.gov/odapc/part40) • [CDC – National Center for Health Statistics – Drug Use FastStats](https://www.cdc.gov/nchs/fastats/drug-use.htm) • [Quest Diagnostics – Employer Solutions, Hair Testing Methodology](https://www.questdiagnostics.com/) • [LabCorp – Occupational Testing Services](https://www.labcorp.com/) ## Ready to get started? AMH Nationwide provides the lab order and arranges collection nationwide. Every non-negative result reviewed by a certified Medical Review Officer. Call (877) 731-6362 or contact us. [Call (877) 731-6362](tel:+18777316362)[Contact Us](https://amhnationwide.com/contact-us/) --- **Need a drug, alcohol, HIV or STD test?** AMH Nationwide is a national lab testing agency operating since 2004, with more than 20,000 collection sites across the United States. Hair, urine, fingernail and blood testing, panels from 5 through 19, for individuals and employers. - Call: (877) 731-6377 - Find a collection site: https://amhnationwide.com/locations/ - Full page: https://amhnationwide.com/how-long-does-hair-need-to-be-for-drug-test/