How this calculator works
The calculator multiplies the number of people by a daily sheet estimate and then by the number of days. Dividing by the sheets on a roll gives the rolls needed, rounded up because shops sell whole rolls, and dividing by the rolls in a pack gives packs, also rounded up. In the other direction, the rolls you already have are multiplied by the sheets per roll and divided by daily use to give days of supply. The daily sheet figures are planning estimates: published averages range from roughly 35 to 60 sheets a person a day, and the three levels bracket that range.
Formula
Sheets used per day = people x sheets per person per day, using 35 for low use, 50 for average and 75 for high use. Rolls needed = sheets per day x days / sheets per roll, rounded up. Packs to buy = rolls needed / rolls per pack, rounded up. Days of supply = rolls on hand x sheets per roll / sheets per day.
Worked example
Two people using an average of 50 sheets each use 100 sheets a day. Over 30 days that is 3,000 sheets, or 15 rolls at 200 sheets a roll, which means two packs of 12. If you already have 24 rolls, that is 4,800 sheets, or 48 days of supply at the same rate.
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Frequently asked questions
How reliable is the sheets per day figure?
It is a planning estimate, not a measurement. Estimates vary with how often people visit, how much they use each time and whether a household uses wet wipes or a bidet. If you have kept track of how long a pack lasted before, use that to pick the level or adjust the sheets per roll.
Should I use sheets or weight per roll?
Sheets are easier to compare when the pack states them, but roll sizes vary a lot. Some manufacturers quote sheet count and others quote roll length or weight. If your pack only gives a total length, estimate sheets by dividing the length by the sheet length.
Does the calculator include kitchen paper or tissues?
No, it is only for bathroom toilet paper. Keep those products separate, because they are used at very different rates and are not interchangeable for plumbing.
Why round packs up separately?
Shops sell packs, not loose rolls. If 15 rolls are needed and a pack holds 12, you need two packs and will have nine rolls left over. The leftover is real, so it is better shown than hidden in a fractional pack.