Last updated: August 2026 · Right Weigh Scale — California Registered Service Agency (RSA #3421)
Answers to the most common questions we get about scale calibration, legal-for-trade certification, and our service in the Bay Area and Northern California. Don’t see your question? Contact us or call (510) 315-8883.
Legal-for-trade & compliance
What does “legal for trade” mean?
“Legal for trade” means a scale is certified accurate and approved for commercial transactions where price is based on weight. The device must be NTEP-approved, properly calibrated, and sealed by an authorized agency. Any scale that sets a customer’s price — at a deli, dispensary, recycler, or truck stop — must be legal for trade under California law.
Who can certify a scale legal for trade in California?
Only a Registered Service Agency (RSA) registered with the California Division of Measurement Standards can place the legal-for-trade seal after calibration, repair, or installation. Right Weigh Scale holds RSA #3421 and is authorized to certify commercial scales across the Bay Area and Northern California.
Does my business need a legal-for-trade scale?
If you buy or sell goods by weight, yes. California requires legal-for-trade scales for grocers, cannabis distributors, recyclers, jewelers, truck stops, farms, and pharmacies — any business where weight sets the price. Scales used only for internal purposes like shipping or portioning do not need to be legal for trade.
What happens if I use a scale that isn’t legal for trade?
Using an uncertified scale for commercial transactions can result in fines, citations, and a condemned (red-tagged) device from your county Weights & Measures office. Customers can also dispute charges. Certifying your scale protects both your revenue and your compliance.
Calibration
How often should a commercial scale be calibrated in California?
County Weights & Measures typically inspects and seals commercial scales annually, and most counties require annual registration. Industry best practice is recalibration every 6 to 12 months — more often for high-use or harsh-environment scales — and re-verification is required after any repair or relocation that affects accuracy.
What is NIST-traceable calibration?
NIST-traceable calibration means the test weights used to check your scale have an unbroken, documented chain of comparisons linking them back to the U.S. national standard at NIST. This gives the highest level of accuracy and legal defensibility. Right Weigh Scale provides NIST-traceable, ISO/IEC 17025-accredited calibration up to 20,000 lb.— see our full calibration services.
Do you provide a calibration certificate?
Yes. Every calibration includes documentation showing NIST-traceable results, performed by a California Registered Service Agency (RSA #3421) and ISO/IEC 17025-accredited lab. These certificates support county compliance, customer audits, and quality-system requirements.— learn more about our accreditation.
What’s the difference between calibration and certification?
Calibration is adjusting and verifying that a scale weighs accurately against traceable standards. Certification (legal-for-trade sealing) is the official act of marking that scale as approved for commerce, which in California only a Registered Service Agency can do. Right Weigh Scale performs both in a single visit.
Equipment & credentials
What’s the difference between NTEP and ISO 17025? NTEP certifies that a scale model is approved for legal-for-trade use in the U.S. ISO/IEC 17025 accredits a calibration lab’s competence to measure accurately with NIST traceability. They work together: Right Weigh Scale sells NTEP-approved equipment and performs ISO/IEC 17025-accredited calibration.
What scale brands do you sell and service? Right Weigh Scale sells and services A&D, Rice Lake Weighing Systems, and Adam Equipment, with over 1,000 products ranging from analytical balances to truck and crane scales. Browse our full scales catalog — All equipment we sell can be calibrated and certified legal-for-trade by our team before use.
Service area & getting started
What areas do you serve?
Right Weigh Scale provides on-site calibration, repair, and installation across the San Francisco Bay Area and Northern California — including Hayward, Oakland, San Jose, Fremont, and surrounding metros — from our facility at 20688 Corsair Blvd, Hayward, CA 94545. Learn more about us.Equipment from our store ships nationwide.
Do you offer on-site service?
Yes. We perform on-site, NIST-traceable calibration up to 20,000 lb, plus repair and installation, across Northern California, along with in-shop service at our Hayward facility. On-site service minimizes downtime by certifying your scales where they operate.
How much does scale calibration cost?
Calibration and service pricing depends on the number, type, and location of your scales, so we quote each job individually. New equipment ranges from about $70 to $20,000+. Call (510) 315-8883 or request a quote for accurate pricing for your equipment and site.
How do I schedule service or request a quote?
Call (510) 315-8883, email info@rwscale.com, or submit a request through our contact page. Tell us your scale types, quantity, location, and whether you need legal-for-trade certification, and we’ll schedule on-site or in-shop service across the Bay Area and Northern California.