FlowBudget: Training-Free Sampling-Budget Estimation for Flow Matching Models

FlowBudget is a training-free estimator that determines the sufficient numerical resolution for sampling from continuous flow-based generators like flow matching models. It uses simulation-free interpolation probes to normalize the leading one-step discretization error by motion, estimates the coefficient from these probes, and maps a numerical tolerance to a step budget using the solver order. This addresses the problem of selecting sampling budgets through expensive FID-versus-NFE sweeps.