Coupon Collector Calculator

Find the expected number of purchases to complete a set.

Fill in the fields below to calculate

Number of Unique Coupons (N)

Enter your values above and tap Calculate to see the result.

Your Results

Expected Draws E(T)

Harmonic Number H(N)

Formula

E(T) = N × H(N)
H(N) = Σ(1/i) for i=1 to N

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Pro Tips

Results update as you type — change any field to see the effect immediately.

Check that every value uses the same unit before comparing results.

Use the copy button to paste the coupon collector figures into a note or spreadsheet.

Nothing is sent to a server, so you can use this with private figures.