Tool

Downtime cost calculator

A cost of downtime calculator for a client website you already maintain. You type the revenue and the orders or leads. It returns the cost of one outage, and a sentence you can paste into the monthly report. I do not borrow an industry average.

How to calculate downtime cost

Calculating the cost of downtime uses only numbers you type, in this order.

1. Revenue per open hour = monthly revenue that depends on the site ÷ hours the site is open that month.
2. Revenue lost per hour = revenue per open hour × the share that actually stops. Use 100% only when those sales do not come back later and do not move to the phone or the counter.
3. Cost of the outage = revenue lost per hour × hours the site was down. Per minute is that hourly figure ÷ 60.
4. Orders or leads per hour = the month's orders or form leads ÷ the same open hours.
5. Orders or leads during the outage = orders or leads per hour × hours down × the same share.

This sum is the sales and the orders or leads. It does not include staff wages, a reputation hit, or ads that kept spending. You cannot see those from outside the site. If the client can price one of them, add it after the sentence. Do not invent it.

Worked example for a small client website

These are the numbers the form starts with. Retype them with what the client told you. They are not a shop I measured, and they are not a typical cost.

Suppose the client says the site is tied to about $8,000 in a month, the shop takes orders on weekdays (8 hours, 22 days, 176 hours), and about 88 orders come through the site. It is down for 3 hours one afternoon, and they count every order in that window as lost.

The cent is rounded after the multiplication. $8,000 ÷ 176 × 3 is $136.3636…, which shows as $136.36. It is not $45.45 × 3.

The form prints this sentence for those inputs: 3 hours offline on the shop is about $136.36 of the sales that depend on the site, at $45.45 an hour. About 1.5 orders or leads in that window, at 0.5 an hour.

Where it goes on the monthly report

The report does not calculate this. A work entry is a date, a title, a short note, a tag, and optional minutes. Put the sentence in the note on the day the site missed, or in the email that links the report.

The public sample is at /demo. Harbor & Co is not a customer. For the period ending 29 September 2026 the uptime line says reached on 332 of 334 checks (99.4%). The day with a miss is 24 September 2026. The sample has no revenue, so it does not show a dollar cost. Open it when you want to show a client where your sentence will sit, next to that uptime line. A single public check, with nothing saved, is the website check. The ongoing count of hits and misses is the uptime section of the client report.

The sentence is arithmetic on the numbers they gave you. It is not lost profit after costs, and it is not a promise that every hour offline deletes that much revenue. If the shop was closed anyway, do not send it.

For the emails around an outage, use the down email templates. For the written record after, use the incident report.

Plans are Starter at $9/month for up to 5 sites, Studio at $29/month for up to 25 sites, and Agency at $79/month for up to 100 sites. Studio is the plan marked recommended. Starter, including a trial, keeps a small Powered by RetainerProof link on the client digest and the public status page. Studio and Agency remove that link. Prices are on the pricing page.

More resources

• Resources
• Pricing calculator
• Downtime emails
• Incident report
• WordPress maintenance report
• Sample care report
• Proposal template
• SLA template
• SSL and domain dates
• Handover email
• Client checklist

Also see pricing and a sample client digest.