How long does it take to become a certified arborist?
ISA does not set a course length. It sets an experience requirement, an application review time and an exam window. This page lays out each number as ISA words it.
Checked against the sources at the bottom of this page on October 8, 2026. Rules, fees and pay change: the source has the last word.
For the ISA Certified Arborist credential, the time is set by experience, not by a course. The ISA program guide says the ISA Credentialing Council sets a minimum of three years of full-time arboriculture work, which education can partly replace. The guide puts one year of full-time experience at 1,795 hours of work. The longer guide to every credential is ISA credentials, one by one. This page only answers the timing question.
The experience requirement
Work that counts is listed in the ISA Certified Arborist program guide: pruning, fertilizing, planting and establishing trees, diagnosing and treating problems, cabling and bracing, climbing, and other services tied directly to arboriculture. It names tree care companies, nurseries, landscape companies, municipalities, state forestry agencies, utility companies and consultancies as places where experience can come from. Documentation is part of the application, and a letter of reference from an employer is acceptable. Self-employed applicants send three letters of reference, which can be copies of invoices, contracts or business licenses.
The guide also lets education shorten the experience time. Each route below still ends with the same exam.
| Route named in the guide | Education part | Full-time experience part |
|---|---|---|
| Three years of experience only | None | 3 years |
| Two-year associate degree | At least two courses directly related to arboriculture | 2 years |
| Four-year bachelor degree | At least four courses directly related to arboriculture | 1 year |
| Assessment-based certificate, 900 hours | At least 90 hours directly related to arboriculture | 2 years |
| Assessment-based certificate, 1,800 hours | At least 180 hours directly related to arboriculture | 1 year |
The guide adds that multiple degree programs cannot be added together to equal a longer program, while hours from several assessment-based certificate programs can be added up. It also says approved registered apprenticeship programs may be considered for an equivalency, and that applicants can see which programs ISA has approved when they apply.
After the experience: application, exam and result
- Application review. The guide says a submitted application is reviewed within five US business days, and that only an approved applicant can enroll for an exam.
- Exam window. For a computer-based exam, enrollment brings a 120-day window in which to book and sit the exam. ISA's page on exam information says a sitting is run by a certification partner or held at a testing center, and that there is no registration on the day.
- Result. The guide says computer-based exams give a result notice right after the exam and that formal results post to the web account within four weeks. ISA's common questions page gives four to six weeks for results to post to the account and be mailed.
- Exam format. 200 multiple-choice questions in 3.5 hours, with a passing score of 76 percent, per the guide.
How long the credential lasts
The guide says the certification is valid for three years. It is kept by retaking the exam or by earning 30 continuing education units in the three-year period and paying a recertification fee. The page on keeping a credential current covers renewal in detail.
What is not on the official pages
None of the three ISA pages above gives a typical number of weeks of study or an average time from first job to certificate. They give the experience requirement, the five-business-day review, the 120-day exam window and the result times, and nothing else about elapsed time. ISA's common questions page also says there are no practice exams, only exam outlines on each credential's information page and suggested study materials in the ISA Store.