Uncertainty and calibration
An estimate is a calibrated range, not a benchmark promise. The calibration feed records model, hardware, runtime, quant, context, batch behavior, and measured throughput. It filters outliers, separates batch-one runs, and fits per-stack efficiency with p10, p50, and p90 bands. The middle value is the planning estimate; a measured result is still the final truth for one machine.
Formula
MBU = measured tps × bytes read per token ÷ peak bandwidth error ratio = measured tps ÷ estimated tps
Worked example: The RTX 4090 8B calibration anchor
For an RTX 4090 and an 8B Q4_K_M model, the physics estimate is 153 tps and the artifact's measured band is 140 to 180 tps. The observed range is about 8.5% below to 17.6% above the estimate, which is why the product shows a band rather than false precision.
low residual = 140 ÷ 153 - 1 ≈ -8.5% high residual = 180 ÷ 153 - 1 ≈ +17.6%