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A/B Test Duration Calculator

Before you launch a 50/50 test, see how many carts it needs and how long that takes at your actual traffic — most low-traffic stores are running tests that can never conclude.

YOUR NUMBERS

CARTS PER DAY

Traffic entering the test, split 50/50 between control and variant.

CURRENT CONVERSION RATE

Share of carts that complete checkout today.

RELATIVE IMPROVEMENT TO DETECT

A 20% relative lift on a 3% rate means detecting a move to 3.6%.

YOUR RESULTS

Detecting

3.0% → 3.6%

Carts needed / variant

13,911

Time to run this test

279 days (~9.3 months)

At this traffic level, a 50/50 test needs longer than most retail seasons to conclude. In practice, most low-traffic stores are running tests that never accumulate enough carts to reach a real answer.

The formula

p1 = current conversion rate; p2 = p1 × (1 + relative improvement) Carts needed per variant = (1.96 + 0.84)² × [p1(1−p1) + p2(1−p2)] ÷ (p2 − p1)² [95% confidence, 80% power, two-sided, 50/50 split] Days needed = carts needed per variant ÷ (carts per day ÷ 2)

Test smarter with the traffic you actually have

NavonaAI runs this same math inside experiment results, so a test isn't called a winner before it has the sample size to back that up.

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