Is the midrange the average hardness?

No. It uses only the highest and lowest readings. Calculate the sample mean from all readings when required.

Can I mix Rockwell and Vickers values?

No. This calculator accepts Rockwell C values on one consistent scale and performs no hardness conversion.

Does a narrow range prove conformance?

No. All readings can cluster outside a specification limit. Check both extreme-to-limit margins.

Can these extremes establish process capability?

No. Capability requires appropriate sample data, distribution analysis and specification limits beyond the two observed extremes.

Heat Treatment, Furnaces & Thermal Processing calculator

Measured Hardness Variation Calculator

Report the range between the lowest and highest Rockwell C readings. Compare those extremes with the two hardness limits on the applicable drawing or specification.

What this calculator does

Report the observed Rockwell C hardness range and the margins to entered specification limits.

Formula used

Observed hardness range = highest reading − lowest reading
Midrange = (highest reading + lowest reading) ÷ 2
Lower margin = lowest reading − lower specification limit
Upper margin = upper specification limit − highest reading

Inputs explained

Lowest Measured Hardness: Lowest Rockwell C reading in the defined inspection set.
Highest Measured Hardness: Highest Rockwell C reading in the same inspection set.
Lower Hardness Limit: Lower Rockwell C limit from the part specification.
Upper Hardness Limit: Upper Rockwell C limit from the same specification.

How to use the result

Best suited to heat-treated lot hardness reviews, specification margin checks.
Does not estimate process capability or a population distribution. Does not include measurement uncertainty or convert hardness scales.

Current U.S. benchmarks

Industrial electricity averages 9.77 cents per kWh across the U.S. (EIA, Jul 2026), up 4.7% from a year earlier. Energy-intensive steps carry this directly into unit cost.

Common questions

Is the midrange the average hardness? No. It uses only the highest and lowest readings. Calculate the sample mean from all readings when required.
Can I mix Rockwell and Vickers values? No. This calculator accepts Rockwell C values on one consistent scale and performs no hardness conversion.
Does a narrow range prove conformance? No. All readings can cluster outside a specification limit. Check both extreme-to-limit margins.
Can these extremes establish process capability? No. Capability requires appropriate sample data, distribution analysis and specification limits beyond the two observed extremes.

Last reviewed 2026-10-06.