Gage Block Temperature Correction

Gage blocks and part tolerances are defined at 20 °C (68 °F) (ISO 1). Enter the length and the shop temperature to see how much the block and the part grow, and the correction when they're made of different materials.

Length Temperature (block and part) Gage block α (×10⁻⁶/°C) Part α (×10⁻⁶/°C)

How it works

ΔL = L × α × (T − 20 °C). If the part and the block are at the same temperature, only the difference in their expansion causes a measuring error. Steel blocks on steel parts nearly cancel; aluminum parts measured against steel blocks don't.

Coefficients are typical room-temperature handbook values (steel 11.5 ≈ 6.4 µin/in/°F; ceramic and chrome carbide from Starrett's published 5.5 and 4.7 µin/in/°F). Check your block certificate and material spec for exact values; ISO 3650 gives 10.8 ± 1.0 ×10⁻⁶/°C for steel blocks.

General shop information only — follow your quality system for compliance work.