[{"data":1,"prerenderedAt":219},["ShallowReactive",2],{"content:\u002Ftools\u002Fuptime-sla-calculator":3,"related:\u002Ftools\u002Fhow-much-downtime-is-99-9-percent,\u002Fglossary\u002Fuptime,\u002Fguides\u002Fhow-to-set-up-uptime-monitoring-for-client-websites":208},{"id":4,"title":5,"body":6,"category":181,"description":182,"extension":183,"faq":184,"h1":197,"meta":198,"navigation":199,"path":200,"published":201,"readingMinutes":202,"related":203,"seo":205,"stem":206,"updated":201,"__hash__":207},"tools\u002Ftools\u002Fuptime-sla-calculator.md","Uptime and SLA calculator (free)",{"type":7,"value":8,"toc":173},"minimark",[9,13,16,21,32,35,39,126,142,146,154,158,161,165],[10,11,12],"p",{},"Pick an uptime percentage and see how much downtime it actually allows. Use the second box to turn the downtime you had into an uptime figure.",[14,15],"uptime-calculator",{},[17,18,20],"h2",{"id":19},"how-is-allowed-downtime-calculated","How is allowed downtime calculated?",[22,23,29],"pre",{"className":24,"code":26,"language":27,"meta":28},[25],"language-text","Allowed downtime = period length x (100 - uptime percentage) \u002F 100\n","text","",[30,31,26],"code",{"__ignoreMap":28},[10,33,34],{},"For 99.9 percent over a 30-day month: 43,200 minutes x 0.1 \u002F 100 = 43.2 minutes. This calculator uses a month of one twelfth of a 365-day year, which is 43 minutes and 48 seconds at 99.9 percent. If a contract says \"per month\", check how it defines one.",[17,36,38],{"id":37},"what-do-the-nines-mean","What do the nines mean?",[40,41,42,58],"table",{},[43,44,45],"thead",{},[46,47,48,52,55],"tr",{},[49,50,51],"th",{},"Uptime",[49,53,54],{},"Common name",[49,56,57],{},"Downtime per year",[59,60,61,73,83,94,104,115],"tbody",{},[46,62,63,67,70],{},[64,65,66],"td",{},"99%",[64,68,69],{},"Two nines",[64,71,72],{},"3 days 15 hours 36 minutes",[46,74,75,78,80],{},[64,76,77],{},"99.5%",[64,79],{},[64,81,82],{},"1 day 19 hours 48 minutes",[46,84,85,88,91],{},[64,86,87],{},"99.9%",[64,89,90],{},"Three nines",[64,92,93],{},"8 hours 45 minutes 36 seconds",[46,95,96,99,101],{},[64,97,98],{},"99.95%",[64,100],{},[64,102,103],{},"4 hours 22 minutes 48 seconds",[46,105,106,109,112],{},[64,107,108],{},"99.99%",[64,110,111],{},"Four nines",[64,113,114],{},"52 minutes 34 seconds",[46,116,117,120,123],{},[64,118,119],{},"99.999%",[64,121,122],{},"Five nines",[64,124,125],{},"5 minutes 15 seconds",[10,127,128,129,133,134,137,138,141],{},"Each extra nine cuts the allowance to a tenth, and the cost of reaching it rises faster than the benefit for most small sites. See the pages for ",[130,131,87],"a",{"href":132},"\u002Ftools\u002Fhow-much-downtime-is-99-9-percent",", ",[130,135,108],{"href":136},"\u002Ftools\u002Fhow-much-downtime-is-99-99-percent"," and ",[130,139,66],{"href":140},"\u002Ftools\u002Fhow-much-downtime-is-99-percent"," for what each level means in practice.",[17,143,145],{"id":144},"what-should-i-promise-a-client","What should I promise a client?",[10,147,148,149,153],{},"Promise only what you can measure and what your hosting can deliver. A single shared host rarely sustains more than three nines, and a promise is only worth something when you monitor it. Define the measurement window, exclude planned maintenance explicitly and keep the check history, so a monthly report can show the number instead of asserting it. Our guide on ",[130,150,152],{"href":151},"\u002Fguides\u002Fhow-to-set-up-uptime-monitoring-for-client-websites","setting up uptime monitoring for client websites"," covers the setup.",[17,155,157],{"id":156},"what-counts-as-downtime","What counts as downtime?",[10,159,160],{},"The definition matters as much as the percentage. Decide in advance whether a slow response counts, how many failed checks in a row make an outage and whether planned maintenance is excluded. Ambiguity here causes more arguments than the number does.",[17,162,164],{"id":163},"where-datumboard-fits","Where Datumboard fits",[10,166,167,168,172],{},"Datumboard shows the health of every client site next to deploys, renewals, search data and costs, so you can see at a glance which sites are failing before a client asks. It is in early access, and you can ",[130,169,171],{"href":170},"#early-access","join the list below",".",{"title":28,"searchDepth":174,"depth":174,"links":175},2,[176,177,178,179,180],{"id":19,"depth":174,"text":20},{"id":37,"depth":174,"text":38},{"id":144,"depth":174,"text":145},{"id":156,"depth":174,"text":157},{"id":163,"depth":174,"text":164},"Free tool","Turn an uptime percentage into the downtime it allows per day, week, month and year, or work out the uptime you actually had from minutes of downtime.","md",[185,188,191,194],{"q":186,"a":187},"How much downtime is 99.9 percent uptime?","About 43 minutes and 48 seconds per month, or about 8 hours 45 minutes and 36 seconds per year. The figure depends on how the month is defined, and this calculator uses a twelfth of a 365-day year.",{"q":189,"a":190},"How do I calculate uptime percentage?","Subtract the downtime from the total period, divide by the total period and multiply by 100. For example, 45 minutes of downtime in a 30-day month of 43,200 minutes is about 99.896 percent uptime.",{"q":192,"a":193},"Why do different calculators give slightly different answers?","They define a month differently. Some use exactly 30 days, others use a twelfth of a 365-day year. The difference is small, but an SLA should say which definition it uses.",{"q":195,"a":196},"Is 99.99 percent uptime realistic for a small client site?","It allows about 52 minutes of downtime a year, which usually needs redundant hosting and fast failover. A typical small site on a single host aims for 99.9 percent, and the cost of each extra nine rises quickly.","Uptime and SLA calculator: how much downtime is allowed?",{},true,"\u002Ftools\u002Fuptime-sla-calculator","2026-10-12",5,[132,204,151],"\u002Fglossary\u002Fuptime",{"title":5,"description":182},"tools\u002Fuptime-sla-calculator","imHx5TuNG-Yl-NLyEvtfFOACPG9lBp7t00AeBBNye5g",[209,212,215],{"title":210,"description":211,"path":132,"category":51},"How much downtime is 99.9% uptime?","99.9% uptime allows 8 hours 45 minutes 36 seconds of downtime a year and 43 minutes 48 seconds a month. See what three nines means for your site.",{"title":213,"description":214,"path":204,"category":51},"What is uptime?","Uptime is the share of time a website or service is available, usually shown as a percentage such as 99.9%. Learn how it is measured and what it allows.",{"title":216,"description":217,"path":151,"category":218},"Set up uptime monitoring for client websites","Choose the right checks, set sensible intervals, avoid false alarms and send alerts to the right place, with a setup you can repeat for every client.","How-to",1791830036271]