Two times on a clock face look simple until you have to do something with the gap between them. Subtracting 09:15 from 14:40 by hand means borrowing across the 60-minute mark, and the same borrowing trips people up whether they're finding a duration, adding time to a start point, or counting whole days between two dates.
This category covers that arithmetic directly: finding the duration between two times, adding and subtracting hours and minutes without a calculator, a quick method for counting hours between two clock times, working out elapsed time from a start and end point, and counting business days between two dates while skipping weekends. Each guide walks through the carrying and borrowing step by step so the method holds up on any pair of times, not just the example given.
Start with the duration guide for the general method. If you already have that down, jump to whichever narrower case — adding time, elapsed time, or business days — matches what you're working on.
Start here
New to the topic? Read How to Calculate the Duration Between Two Times first — it's the cornerstone of this category and covers the core method the rest build on.
All guides in this category
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Category FAQ
Which post should I read first?
Start with How to Calculate the Duration Between Two Times. It's the cornerstone of this category and covers the core method; the other posts go deeper on one piece each.
What does the Time Math & Duration category cover?
How to find the duration between two times, add and subtract hours and minutes, calculate elapsed time, and count business days between two dates.
Do I need to read these in order?
No. Each post answers its own question and stands alone. Read the one that matches what you need right now; the guides link out to each other where it's relevant.