Free tool
What a year of teacher absences costs your building
Enter your staff size, absence rate, sub pay, and fill rate to see the annual coverage bill including the days nobody fills.
Free tool, no sign up
How fast a reusable sub folder pays back the time to build it
Enter your period count and how long plans take you now to see the build cost in hours and the payback in absences.
Writing a day of sub plans from scratch while sick is the most expensive twenty minutes in teaching. It happens at 5:40 in the morning, under a deadline, with no access to the room, and it produces the thinnest plans of the year. Banking a few reusable days moves that work to an afternoon in September when you are well and the materials are in front of you.
This calculator prices that trade in hours. Put in how many periods you teach, how long one period of fresh plans takes you, how many days you want banked, and how long a refresh takes once the room facts are already written down. The payback figure is the number of absences before the build pays for itself.
Your result
Hours to build the library once
5.5
One time cost, best spent in the first two weeks of the year.
Minutes per absence without a library
145
What each unplanned day currently costs you before 8 a.m.
Hours saved this school year
14.6
Time returned across every absence you expect to take.
Absences to pay back the build
2.6
How many days out before the library has repaid its build time.
The hours saved are real but the bigger return is the quality of a plan written when you were well rather than feverish.
Why the morning scramble costs more than the writing
Teachers underestimate the scramble line because it is scattered. Texting the grade lead, emailing plans from a phone, remembering that the seating chart changed in January, asking someone to unlock the cabinet, and then lying awake wondering whether period six got the right handout. Thirty five minutes is a conservative default for that whole sequence.
A banked day collapses that to one message and a send. The room facts, the schedule, the seating chart, and the fallback work were already written down in October, so the only decision left is which banked day to use. That is the part of the trade that does not show up in a lesson planning spreadsheet.
Building the library without losing a weekend
Do not try to bank three days in one sitting. Build page one first, the orientation page that does not change: room number, bell schedule, two adults by name and room, logins, exits, and the hall pass policy. That page alone cuts the panic out of an unplanned absence even if the plans behind it are thin.
Then add one banked day a week for three weeks, using activities that already worked this fall and need no setup. Aim for work that stands alone, runs in the stated minutes, and has a fallback for the class that finishes early. Refresh whichever day you use within a week of coming back, while you still remember what the sub said went sideways.
Questions about this calculator
How many banked days are enough?
Three is the common answer because a flu week is usually two or three days and repeating the same lesson to the same class is awkward. Teachers with chronic conditions or young children at home often bank five. Elementary teachers can bank fewer full days because one banked day covers all subjects.
Does this work for specials and elective teachers?
Yes, and the payback is often faster because the same banked block repeats across many sections in a day. Enter your section count as periods and the refresh minutes for one block. Art, music, and PE teachers usually see the shortest payback of anyone.
What if my plans go stale before I use them?
That is what the refresh minutes model. A banked day whose room facts carry forward stays usable, and the activity swap is the only fresh work. Check the login list twice a year, in October and again in January, because expired logins are what actually kill an old plan.
More free tools and working documents
Working document
The one day substitute handoff template
A fill in template that turns a sick day into a taught day, written so a substitute who has never met your class can run it cold.
The figure on screen is the argument
Whatever this calculator just returned for your building, the plans a substitute teaches from are the cheapest line on it to fix. Book a short demo and we will build one ready to teach day for your room, with timed blocks, a seating chart, and fallback work for the section that finishes early. You will know by the end whether it beats what is in your folder now.