Universal Suffering Units (USU): A Calibrated Additive Unit of Experienced Suffering

We present the Universal Suffering Unit (USU), a calibrated, additive unit of experienced suffering that scales with intensity, duration, and affected population, enabling aggregation across people, regions or countries, and time. We define USU as k * sum I^p * Δt, where I is a 0–10 intensity rating, p >= 1 is an exponent that modestly up-weights high intensities, and k is a calibration constant. We calibrate the unit so that a reference trajectory of renal colic (kidney-stone pain) equals 1.0 USU, propose a simple rule for co-occurring harms, and recommend reporting medians with 90% uncertainty intervals from Monte Carlo simulations. Using publicly available data, we illustrate the framework with two examples: dengue in Brazil (epidemiological weeks 1–23 of 2024) and flood-related displacement in Rio Grande do Sul, plus a year-over-year dengue comparison and a sensitivity analysis over p in {1.0, 1.25, 1.5}. These illustrations show how large numbers of moderate episodes and smaller numbers of longer, disruptive episodes can be expressed on a common experiential scale, while remaining interpretable via an anchor ladder. We discuss validation strategies, highlight ethical guardrails and misuse risks, and argue that USU is best used alongside DALY/QALY and routine operational indicators as a decision-support tool for comparing heterogeneous harms, rather than as a stand-alone welfare metric.