Stopwatch & Timer Calibration: Turnaround Times, On-Site Services & How It Works
Tra-Cal Lab has provided ISO/IEC 17025 accredited, NIST-traceable stopwatch and timer calibration for over 35 years — trusted by NASA, the U.S. military, and NIST. We service every major brand, from Extech and Hanhart to the wider timing market, with faster turnaround and lower cost than the OEM. We offer expedited services, on-site calibration and Mid-Atlantic pickup and delivery to keep your operation running. Every certificate includes as-found/as-left data, so your measurements stand up to any audit.
Key Summary
Stopwatch & Timer calibration verifies elapsed-time accuracy against a NIST-traceable time base over defined test intervals, using either the totalize or time-base method described in NIST guidance, with results documented on a calibration certificate. Standard turnaround is 3-5 business days with overnight rush available, and most stopwatches and timers should be calibrated every 12 months by an ISO/IEC 17025 accredited lab.
Why Choose Tra-Cal?
ISO/IEC 17025 Accredited
Our lab is independently audited every year by ANAB to the industry's most rigorous quality standard, so every calibration is audit-proof.
Overnight Rush Available
When downtime isn't an option, expedited service gets your instrument calibrated and back in your hands overnight or within three days.
NIST-Traceable
Every measurement we make traces directly back to national standards, giving your results documented accuracy you can defend.
Trusted by NASA, the U.S. Military, and NIST
The organizations with the most demanding measurement requirements in the country choose Tra-Cal — yours can too.
Stopwatch & Timer Calibration Turnaround
| Service | Turnaround |
|---|---|
| On-site Calibration Service | Same-Day |
| Standard calibration with certificate | 3-5 business days |
| ISO/IEC 17025 accredited calibration | 4-6 business days |
| Expedited / rush | Overnight to 3 days |
Stopwatch & Timer Brands & Models We Calibrate
| Manufacturer | Popular Models We Calibrate |
|---|---|
| Extech | 365515 |
| Hanhart | 260.1760-VO |
Don’t see your model?
We support over 100 test equipment manufacturers — contact us and we’ll confirm coverage for your exact instrument.
Equipment & Standards Required
We maintain the following equipment and conditions required to calibrate a stopwatch and timer accurately:
Rubidium or GPS-disciplined time base traceable to NIST with at least a 4:1 test accuracy ratio
Calibrated time-interval counter or stopwatch calibration system with automated start/stop actuation
Manufacturer’s calibration procedure and the applicable timing specification
Stable environment: 23 °C ± 5 °C, controlled humidity
NIST-traceable reference standards and documentation system
How to Calibrate a Stopwatch & Timer: Step-by-Step
Step 1: Inspect the unit and stabilize the environment. Check the display, buttons, and battery condition, then allow the stopwatch and reference system to acclimate at 23 °C ± 5 °C.
Step 2: Perform “as found” verification. Record elapsed-time results over each test interval before any adjustment. As-found data proves whether prior timed processes were within tolerance.
Step 3: Measure elapsed time over short and long intervals. Compare the unit against the traceable time base over at least a short and a long interval so both resolution and time-base drift are captured, and compare against manufacturer tolerance limits.
Step 4: Adjust, re-verify, and document. Correct any out-of-tolerance results where the design allows, repeat the verification, and issue a calibration certificate with as-found/as-left data and measurement uncertainty.
Pro tip from our lab: Always request as-found/as-left data on your certificate. Without it, you can’t assess whether measurements taken before calibration were reliable — a common audit finding.
How Often Should You Calibrate a Stopwatch & Timer?
| Usage Profile | Recommended Interval | Notes |
|---|---|---|
| Daily industrial / field use | 6–12 months | Shorten after drift or overload events |
| General lab / bench use | 12 months | Industry-standard default |
| Regulated environments (ISO 9001, FDA, A2LA audits) | Per quality system, typically 12 months | Interval must be documented and justified |
ISO/IEC 17025 does not specify fixed calibration intervals. It requires that intervals be reviewed and adjusted as necessary to maintain confidence in the equipment. Recommended intervals are typically 6–12 months, adjusted based on documented risk assessment and historical stability data per the lab’s calibration program. A2LA and ANAB are accreditation bodies — distinct from quality-system frameworks such as ISO 9001 or FDA requirements.
Frequently Asked Stopwatch & Timer Questions
Q: How much does stopwatch and timer calibration cost?
A: Stopwatch & Timer calibration cost depends on the number of test intervals and functions checked, the required uncertainty, whether the unit is mechanical or digital, and the turnaround selected, and whether accredited (17025) certification is required. Contact Tra-Cal for a quote.
Q: Can I calibrate a stopwatch and timer myself?
A: You can perform verification checks against a known reference, but formal calibration requires traceable standards with a 4:1 accuracy ratio and documented uncertainty.
Q: What is the difference between calibration and adjustment?
A: Calibration is the documented comparison against a standard; adjustment is the correction made when readings fall outside tolerance.
Q: How long does calibration take?
A: Standard turnaround is typically 3-5 business days; Tra-Cal offers expedited service options.