This math is why the stories sting. Merchants report finding a dead add-to-cart button on Cyber Monday itself, and "$20,000 lost this month" traced to a checkout bug that had been live for weeks. LSKD did $10M in the first hour of a BFCM launch — at that scale, a broken hour isn't a rounding error, it's the quarter.
What does a dead checkout cost you per hour?
Roughly your full sales rate, for every hour it stays down — and a broken peak hour costs 2–3× that. Enter your monthly revenue and see your own numbers instantly.
method: monthly ÷ 730 hrs = avg/hr · peak = 2–3× avg · BFCM day = 5–10× a normal day
One broken hour
—
average → peak-hour range
One broken day
—
a silent weekend = 2–3× this
One broken BFCM hour
—
at 5–10× normal daily volume
Honest ranges, not precision: sales cluster in evenings and weekends, so which hour breaks decides the real cost. What you type stays in your browser — only anonymous usage counts are sent.
The expensive part isn't the breakage — it's the not knowing.
Bilby visits your store every night like a real customer and emails you the screenshot the moment the buy path breaks. You fix it before the numbers above happen.
Straight answers.
How much does e-commerce downtime actually cost?
Roughly your full sales run-rate for every hour the buy path is down. A $50k/month store averages ~$69/hour — but sales cluster in evenings and weekends, so a broken peak hour typically costs $140–$210 for that store. On Black Friday, one broken hour can cost more than a normal week.
Doesn't my uptime monitor cover this?
Only for full outages. Uptime monitors check that your homepage returns HTTP 200 — and your homepage can return 200 while the add-to-cart button is dead or a theme update broke checkout. Those cost the same revenue and last longer, because nothing alerts you. That gap is exactly what Bilby exists for: it shops your store nightly the way a customer would.
How do merchants usually find out?
From the sales graph — days or weeks later. The failure is silent by design: the site looks fine, ads keep spending, and only the conversion rate knows. The calculator's per-day figure times "how long until you'd notice" is the number that should worry you.
How accurate is this?
It's an honest range, not a prediction: monthly revenue ÷ 730 hours for the average, a 2–3× multiplier for peak hours, 5–10× normal daily volume for BFCM. Your real cost depends on which hour breaks — which is the point: you don't get to choose.
A DEAD CHECKOUT COSTS