Free Preventive maintenance interval calculator
Hours or months: which comes first?
Your manual says hours or months, whichever comes first. Type how many hours your machine runs a week. You get the days and the next due date.
Run two shifts? A 500 hour, 3 month job can come due in about 6 weeks.
Before you go by this date
- Got an hour meter? Go by the meter. This date is a guess from your shift hours.
- Does your manual give a shorter time for dust, heat, or hard use? Use that number.
- Sooner is not always better. Jobs that open up the machine can cause new problems. Use the manual's number for those.
- Some checks are set by law, like the forklift check before use. Do those on time, no matter what this page says.
- Keep a record each time you do the job. Your warranty may need it.
- Not sure? Call the maker or your dealer.
How often
77 days
That is about 11 weeks.
Next due
Thursday, December 17, 2026
The hours come first.
500 hours at 45 hours a week is 77 days.
3 months is 90 days.
This is a guide. Your manual comes first.
Change the numbers to do the next job. Your hours a week stay put.
Have more jobs to track?
Our Preventive Maintenance Scheduler is a spreadsheet. Type this number in its Every (days) box. It finds each next due date. It turns a job red when it is late.
It holds up to 100 jobs. It works in Excel 2019 and up, and in Google Sheets. $12, one time. Gumroad sends it the minute you pay.
Run more than one shift? The hours come first.
Most manuals give a time limit that fits one shift, about 40 hours a week. Run more, and the hours run out first. Here is a 500 hour, 3 month job.
One shift (40 hours a week): 87 days, about 12 weeks.
Two shifts (80 hours a week): 43 days, about 6 weeks.
Three shifts (120 hours a week): 29 days, about 4 weeks.
Go by the calendar alone, and a two shift machine runs about 1,000 hours between jobs. That is twice what the manual says.
What do your stops cost? Try the downtime cost calculator. Want your OEE too? Try the OEE calculator.