Pull-off adhesion testers on coatings, overlays and concrete surfaces read a load; the spec asks for a stress. Enter the dolly diameter and paste your readings.
Test setup
Readings
#
Load
Stress (MPa)
Stress (psi)
Result
Summary
Readings
–
Dolly area
–
Mean stress
–
Minimum stress
–
Maximum stress
–
Below required minimum
–
Stress = pull-off load ÷ dolly area (π × d² ÷ 4). Calculated with the free tool at calyx-ai.net/qa/pull-off-strength-calculator/ (Quality Tester Solutions LLC).
Nothing you type is uploaded or saved.
How the stress is calculated
Pull-off stress = load ÷ dolly area, with area = π × d² ÷ 4. With load in newtons and area in mm² the result is in MPa (N/mm²); psi = MPa × 145.0377 (exact factors: 1 lbf = 4.4482216152605 N, 1 in = 25.4 mm). Two checks: 3 kN on a 50 mm dolly is 1.53 MPa, and 1 kN on a 20 mm dolly is 3.18 MPa.
The calculator uses the nominal dolly diameter you enter. It does not choose the dolly size, the number of readings or the acceptance value, and it does not record failure mode (adhesive, cohesive, substrate); those come from your spec and the test method you follow. Testers that display stress directly may use their own area setting; compare against the instrument's documentation.
The Fastener & Anchor Pull-Test Report Templates pack has a 40-row proof-test report with automatic PASS/FAIL, ultimate-load statistics, a calibration log, a unit converter, a printable procedure checklist and a standards index. $49 one-time, from Quality Tester Solutions LLC, the company behind Force-Test pull testers.