What this actually computes
Start date plus interval, for every topic, on the ladder you picked. That is the whole calculation. The value is not in the arithmetic but in the second view: once every topic is dated, the tool regroups the dates and shows you how many sessions land on each day. A list of seven chapters on the standard ladder produces 35 sessions, and if they all start together, seven of them are due on day one, seven more on day three, and the calendar quietly becomes undoable. Seeing that before the week starts is the point.
Name topics the way you would want to read them cold. "Grounding and bonding" survives three weeks of not looking at it; "ch. 5 part 2" does not, and the by-date list is only useful if it works as a to-do list without further translation.
The ladders on offer, and how much to believe about them
The default is an expanding ladder at 1, 3, 7, 14 and 30 days after the start date: close together at first, further apart later. The alternative preset is Leitner doubling at 1, 2, 4, 8, 16 and 32 days, which comes from the physical card-box method where a card you get right moves to the next box and waits twice as long. Custom takes your own comma-separated numbers, each counted as days from the start date, deduplicated and sorted, up to twelve of them.
Be clear about what is and is not established here. The finding that holds up well is that spacing your review beats massing it into one session for the same total study time — that has been replicated across a great many studies and materials. What has not been settled is any one interval set. Different systems use different ladders, the published research uses different ones again, and the best gap turns out to depend on how long you need to hold the material, how hard it is, and how well you knew it going in. Nobody can honestly tell you that 1/3/7/14/30 retains a specific percentage, and this tool does not try to.
There is also a real difference between a fixed ladder and an adaptive one. Algorithms in the SM-2 family, and the schedulers that descend from them, change each interval based on how easily you recalled that specific item — a card you fumbled comes back sooner, a card you knew cold gets pushed further out, and the two diverge quickly. A fixed ladder gives every topic the same treatment regardless. That makes it easy to print and easy to follow, and it means the schedule will be too slow for the material you already know and too fast for the parts you keep missing. Adjust it as you go rather than treating the printout as an instruction.
Days off and week start
By default nothing moves; a review that lands on a Sunday stays on Sunday, which is correct for anyone who studies on weekends. The second option pushes Saturday and Sunday to the following Monday. The third also skips US federal holidays, with the usual observation rule — a holiday on a Saturday is observed the Friday before, on a Sunday the Monday after — and it is computed by rule, so any year works rather than one hard-coded year. State holidays, school breaks and company closures are not in there. Any date that got moved is labelled in the by-topic table with the reason. Expect pushing to concentrate work on Mondays; the load bars show exactly how much.
The printed calendar starts weeks on Sunday or Monday, your choice. It is a setting rather than an assumption because both are normal — US wall calendars overwhelmingly start Sunday, most of the rest of the world and the ISO week standard start Monday, and a calendar that disagrees with the one on your wall is worse than no calendar.
Breaking up a pile
The stagger option treats each topic as having started one day later than the one above it, cycling back after seven. Seven topics that would otherwise all be due together spread across a week instead. Only turn it on if you genuinely will study them in that order — otherwise you have moved the dates without moving the work. Even off, it is worth toggling once just to see the difference in the load bars: green under five a day, amber at five, red at eight and above. Those thresholds are display conventions, not findings; the number you can actually absorb in a day is yours to discover and probably lower than you would like.
Questions people ask
Why 1, 3, 7, 14, 30 rather than some other set?
Because it is a widely used expanding pattern that is easy to keep in your head, not because it has been shown to beat its neighbours. The general principle that spacing beats cramming is well supported; the specific rungs are convention. If a different set fits your term dates or your exam better, put it in the custom field.
I missed a day. Do I rebuild the whole schedule?
No. Collect just the topics you missed, run a second schedule with today as the start date, and keep the first one for everything still on track. Since the calculation is only start date plus interval, any date works as a start date and the two schedules coexist without interfering.
Can this adapt to how well I remembered something?
Not on its own — it produces a fixed ladder and every topic gets the same one. Adapting per item is what SM-2-style algorithms in spaced repetition software do, and if your material is large or long-running that is the better tool. This one earns its keep when you want a schedule on paper for a fixed set of topics over a defined period.
Is my topic list saved?
No. The schedule and the print document are built in the browser and a refresh clears the fields. Print the calendar or keep the text copy if you want it to survive.