Mask vs No Mask Calculator
HealthEstimate relative infection risk reduction from wearing a mask, based on source and receiver mask filtration efficiency. An educational model, not medical advice.
Estimated Risk With Both Masked
5.00%
Relative Risk Reduction
75.00%
What is a Mask vs No Mask?
The Mask vs No Mask Calculator estimates relative infection risk reduction when one or both people in an interaction wear masks, based on each mask's filtration efficiency. It's a general educational model illustrating how source and receiver filtration compound, not a personalized medical risk assessment.
For a related probability model, see the Event Risk Calculator.
How to use this Mask vs No Mask calculator
- Enter your baseline transmission risk assumption with no masks.
- Enter the infected person's mask filtration efficiency (0% if unmasked).
- Enter your own mask filtration efficiency (0% if unmasked).
- Read the Estimated Risk With Both Masked and Relative Risk Reduction instantly.
- Try different efficiency combinations to see how one-way versus two-way masking compares.
Formula & Methodology
Adjusted Risk = Baseline Risk × (1 − Source Mask Efficiency) × (1 − Receiver Mask Efficiency) Relative Risk Reduction (%) = ((Baseline Risk − Adjusted Risk) ÷ Baseline Risk) × 100 Worked example — a 20% baseline risk, with both people wearing masks at 50% filtration efficiency: Adjusted Risk = 20% × (1 − 50%) × (1 − 50%) = 20% × 0.5 × 0.5 = 5% Relative Risk Reduction = ((20% − 5%) ÷ 20%) × 100 = 75% This illustrates how two masks at moderate efficiency combine to a much larger overall risk reduction than either mask alone.
Frequently Asked Questions
It depends on mask filtration efficiency and whether one or both people involved are wearing one — this calculator models the combined effect using both the infected person's and your own mask filtration efficiency to estimate an adjusted risk figure.
Source control — filtering respiratory droplets and aerosols at the point they're released — is generally considered highly effective, since it stops particles before they spread into the air, which is why the infected person's mask (source) plays a major role in this model alongside the receiver's mask.
Mask filtration efficiency describes what percentage of particles a mask blocks from passing through, which varies significantly by mask type — cloth masks are generally lower, surgical masks are moderate, and well-fitted N95/KN95-style respirators are generally higher.
The calculator multiplies the baseline risk by the fraction of particles that pass through the source's mask, and then by the fraction that pass through the receiver's mask, reflecting how filtration at both ends compounds to reduce overall risk.
Because the two filtration effects multiply rather than add — if each mask blocks half of particles, using both masks together blocks a much larger share overall than either mask blocks individually, which is the compounding effect this calculator models.
No — this is a general relative-risk model reflecting the mechanics of mask filtration and is not tuned to any single illness's specific transmission characteristics.
Baseline risk depends heavily on setting, proximity, duration, ventilation, and the specific illness involved, so this input should be treated as a rough estimate for exploring relative differences rather than as an official baseline transmission figure.
Yes, significantly — a poorly fitted mask with gaps around the edges will have real-world filtration efficiency well below its rated material filtration, so the efficiency percentage entered should reflect a realistic fitted performance, not just the mask material's rated efficiency.
No — this is an educational model illustrating the relative mechanics of mask filtration, not a personal safety determination; actual risk depends on many additional real-world factors this simplified model doesn't capture.
The [Event Risk Calculator](/event-risk-calculator/) estimates the chance someone at a gathering is infectious in the first place, while this calculator estimates how much mask use might reduce transmission risk if exposure occurs — the two models address different parts of the same broader topic.
Also known as