[{"data":1,"prerenderedAt":77},["ShallowReactive",2],{"page:type=timer&slug=12-hours&locale=en":3},{"locale":4,"alternates":5,"title":8,"description":9,"h1":10,"lead":11,"breadcrumbs":12,"sections":21,"faq":36,"related":49,"updated":71,"tool":72,"schema":74},"en",{"es":6,"en":7},"\u002Ftemporizador\u002F12-horas","\u002Fen\u002Ftimer\u002F12-hours","12 hours timer ⏱ online with alarm","Free 12 hours timer: press Start and an alarm rings when it ends. Full screen, several sounds and works offline.","12 hours timer","12 hours countdown with alarm.",[13,16,19],{"name":14,"path":15},"Home","\u002Fen",{"name":17,"path":18},"Timer","\u002Fen\u002Ftimer",{"name":20,"path":7},"12 hours",[22,26,32],{"paragraphs":23},[24,25],"This timer is set to 12 hours. That is 43,200 seconds, 720 minutes, 43,200,000 milliseconds. It is 50% of a day.","During 12 hours a resting heart beats about 50,400 times and a person walks roughly 57,600 metres at an easy pace.",{"heading":27,"list":28},"What is a 12 hours timer good for?",[29,30,31],"intermittent fasting","bread dough and fermentation","medication reminders",{"heading":33,"paragraphs":34},"How to use it",[35],"Press the space bar or the Start button. When it reaches zero your chosen sound plays; on the main timer page you can add and chain several timers for intervals. Sound and volume settings are saved in your browser.",[37,40,43,46],{"q":38,"a":39},"How many seconds is 12 hours?","12 hours equals 43,200 seconds.",{"q":41,"a":42},"How do I set a 12 hours timer?","Press Start: the time is already set. You can pause it, reset it, change the sound or go full screen.",{"q":44,"a":45},"Will it ring if I switch tabs?","Yes. The timer keeps running in the background and rings when it ends as long as the page stays open; the tab title shows the time left.",{"q":47,"a":48},"Will my screen turn off?","In supported browsers the \"Keep the screen on\" option uses the Wake Lock API to prevent it.",[50,53,56,59,62,65,68],{"label":51,"path":52},"7 hours timer","\u002Fen\u002Ftimer\u002F7-hours",{"label":54,"path":55},"8 hours timer","\u002Fen\u002Ftimer\u002F8-hours",{"label":57,"path":58},"9 hours timer","\u002Fen\u002Ftimer\u002F9-hours",{"label":60,"path":61},"10 hours timer","\u002Fen\u002Ftimer\u002F10-hours",{"label":63,"path":64},"24 hours timer","\u002Fen\u002Ftimer\u002F24-hours",{"label":66,"path":67},"All timers","\u002Fen\u002Ftimer\u002Flist",{"label":69,"path":70},"Stopwatch","\u002Fen\u002Fstopwatch","2026-10-23T13:43:26.166Z",{"seconds":73},43200,{"app":75},{"name":10,"category":76},"UtilitiesApplication",1792763006153]