How this calculator works
The calculator divides the hours you wear a mask each day by the planned wear time for the mask type, then rounds up, because you cannot wear part of a mask. Multiplying by the number of days gives the total to have on hand, and multiplying by the price gives a supply cost. Cloth masks are treated as washable and reusable with one clean mask per wear period. Surgical masks and replacement filters are single-use, and a respirator is planned for a full working day. These are planning intervals for buying supplies, not statements about how long a mask protects you.
Formula
Masks per day = hours worn per day / planned wear hours per mask, rounded up. Masks needed = masks per day x days. Total cost = masks needed x price. Cost per day = total cost / days. Planned wear hours: cloth 8, surgical 4, N95 or N99 8, replaceable filter 4.
Worked example
Eight hours of wear a day with a surgical mask planned at four hours each means two masks a day. Over 30 days that is 60 masks, which costs 60 at one dollar each, or 2 a day.
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Frequently asked questions
Is the planned wear time a safety guarantee?
No. It is a planning number for buying supplies. Follow the guidance of your local public health authority and the manufacturer instructions for the product you actually use, and replace a mask sooner if it becomes damp, dirty or damaged.
Does this calculator give medical advice?
No. It does not assess whether a mask is appropriate for you, how well it fits or how much protection it provides. It only multiplies wear hours into a count and a cost. Ask a health professional or public health authority for guidance specific to your situation.
How do reusable cloth masks change the count?
The calculator plans one clean cloth mask per eight hour wear period and does not model the number of masks you rotate between washes. If you have five cloth masks and wash them weekly, you may need fewer than the total shown, as long as a clean one is always dry and available.
Why round up the masks per day?
A mask is a whole object. If you wear for five hours and plan four hours per mask, you need two masks that day, not 1.25. The rounding is applied per day, so the total over a long period stays realistic.