How Long Toilet Paper Lasts

The How Long does Toilet Paper Last calculator estimates the number of days a supply of toilet paper will last based on the number of people and some personal habits.

INSTRUCTIONS: Enter the following:

• (RTP) Rolls of Toilet Paper
• (N) Number of People
• (NL) Number of Ladies
• (PPD) Average number of Poops per Day per person (default 1.2)
• (SPP) Average sheets of toilet paper per Poop (default 12)
• (SPR) Sheets per Roll (default 150)

Toilet Paper Supply Duration (TPSD): The calculator returns the estimated number of days your supply of toilet paper will last.

The Math / Science

The typical roll of high end toilet paper (e.g. Charmin) has a little over 150 sheets per roll.  Most people go once per day, but some go more.  Being frugal, most people will use 12 sheets of toilet paper per visit to the toilet.   Note: since ladies also use Toilet Paper after urination, there is added toilet paper consumption for each lady or girl in the house.  The assumption is seven (7) visits to pee per lady and five (5) toilet paper squares per visit.

The formula for the Toilet Paper Supply Duration is:

    TPSD = (RTP * SPR) / (N * PPD * SPP + NL*35)

where:

• TPSD = Toilet Paper Supply Duration
• RTP = Rolls of Toilet Paper in current supply
• N = Number of People
• NL = Number of Ladies or Girls
• SPR = Sheets per Roll
• PPD = Poops per Day
• SPP = Sheets of Toilet Paper per Poop