Spaced Repetition Calculator: How Many Cards a Day?

How this spaced repetition calculator estimates your load

The tool models one card the way the SM-2 algorithm from SuperMemo does. A card graduates after its short learning steps, then gets its first interval of one day, its second of six days, and after that each interval is the previous one multiplied by the ease factor. Higher review counts are not a bug: they are what a growing deck of overlapping schedules produces.

Why the reviews pile up

The AnkiWeb manual is blunt about this. Studying new cards temporarily increases the number of reviews you need to do a day, because newly-learned material has to be repeated a number of times before the delay between repetitions can increase appreciably. Add twenty cards today and you are not adding twenty reviews once; you are adding a cluster of near-term reviews that overlaps with yesterday's cluster and last week's.

The 10x anchor it is calibrated to

Rather than invent a multiplier, the simulation is pinned to AnkiWeb's own figure: consistently learning twenty new cards a day leads to roughly two hundred reviews a day. That ten-to-one ratio is the calibration target the model has to hit before any other number it reports can be trusted, and it does hit it.

What it does not know

This is an estimate. It assumes you grade honestly and study every day; a missed day dumps its reviews onto the next one, and a lot of Again presses will push your real load above the line. As AnkiWeb warns, more than one user has excitedly studied hundreds of new cards over their first few days and then been buried by the reviews. The point of the number is to set that expectation before you feel it.

How many cards a day should you do?

There is no single right answer, but there is a well-mapped range. Cade McNiven, who has written carefully about pacing, lays it out: fewer than ten a day is an advanced maintenance pace, ten to fifteen is slow and steady, twenty to twenty-five is a solid standard, thirty is about the sustainable cap for most people, and forty to sixty is the beginner range for someone clearing a large deck. Past a hundred a day is an extreme short burst, not a routine.

The reason those numbers matter is the time behind them. At twenty new a day you settle near two hundred reviews, close to half an hour of daily reviewing at nine seconds a card. Push to a hundred new a day and McNiven puts the total near two and a half hours a day. That is the trade the reverse mode above makes concrete: give it a minutes-a-day budget and it finds the largest new-card pace that fits inside it.

Finishing time follows the same logic. For a 3,500-item deck McNiven figures about 175 days at twenty a day, about 117 days at thirty a day, and about 35 days at a hundred a day. Faster clears the deck sooner and costs much more reviewing on the way, so the sustainable pace usually wins in the end.