Mask vs No Mask Calculator

Mask vs No Mask Transmission Model

This calculator estimates how individual and population-wide mask use may reduce COVID-19 spread using a simplified reproduction-number model. It compares effective R, cumulative secondary infections over a chosen time window, and illustrative lives protected when mask adoption increases.

How Effective R Is Calculated

The baseline reproduction number R₀ (default 2.5, range 2.4–4) represents transmission with no interventions. Mask adoption is entered as a percentage of the population wearing masks correctly. Combined mask efficacy depends on whether you wear a mask:

• When you wear a mask: combined efficacy = 2e − e² (protection in both directions).
• When you do not wear a mask: combined efficacy = 1 − e (protection from others' masks only).

Effective R = R₀ × (1 − adoption × combined efficacy). Cumulative secondary infections are estimated over N days using a 5-day serial interval: infections ≈ R_eff^N/5.

Mask Filtration Efficiencies

Filtration values are based on common fabric and medical mask research (Konda et al., 2020). Cotton (~80%), silk (~54%), flannel (~57%), chiffon (~70%), surgical (~70%), N95 (~99%), and hybrid combinations are included. You may also enter a custom efficacy between 0 and 1.