Why the carry goes wrong by hand
Time is base sixty and everything else you add all day is base ten, so the slip is structural rather than careless. Every entry here is converted to whole minutes on the way in, added as minutes, and turned back into hours and minutes only at the very end. There is no intermediate H:MM value for a carry to go wrong in. The results show H:MM and decimal hours side by side for the same reason: 1:30 is 1.5 decimal hours, not 1.3, and payroll systems and invoices usually want the decimal while time clocks and calendars give you the H:MM. Copying one into a field expecting the other is the second most common way a timesheet ends up wrong, and seeing both together makes it obvious.
Mixed notation is fine
Each line is read on its own, so there is no reason to normalize anything first. 1:30, 1:30:45, 1h 30m, 90 min, 1.5 hours and 1.5h all land on the same value. The only case that needs a decision is a bare number with no unit, because 90 is obviously minutes and 1.5 is obviously hours but nothing distinguishes them mechanically — that is what the selector at the top settles. If your list mixes both conventions, one of them will be read wrong, so write the unit on those lines. A leading minus subtracts, which is how a break goes in: Lunch break, -1:00. Task and time are best separated with a comma, but with no comma the line is split on whitespace from the left and the first chunk that reads as a duration is taken as the time, so Client call 3 45m keeps "Client call 3" as the name.
Rounding, and where the difference lands
Plenty of work is billed in six-minute or fifteen-minute increments, and when you round changes the answer. Rounding each entry up before adding stacks one partial increment per entry: at fifteen minutes, ten two-minute tasks are twenty real minutes and two and a half billed hours. Rounding only the total rounds once, so the gap can never exceed a single increment. Which is correct is a contract question, not an arithmetic one. Wording like "a fifteen-minute minimum per item" means per entry; silence usually means the total. The results show the unrounded total next to the rounded one so you can see the size of the difference before an invoice goes out with it.
Merging names
With merging on, three lines called Build become one task with the hours added and the entry count shown. That is what you want when the log was written a day at a time and you are looking back at where the week went. Names are compared exactly after trimming the surrounding spaces, so Build and Build are the same task and Build and Build (phase 2) are not. Shares are calculated against the sum of the positive tasks only, so subtracted breaks come off the total without inflating the denominator — the percentages describe the composition of time actually worked. If you would rather see every line on its own row, turn merging off.
Questions people ask
Do I have to write the times consistently?
No. Each line is parsed independently, so 2:30 on one line, 150 min on the next and 2.5 hours after that all come to the same thing. The exception is a bare number with no unit, which follows the setting at the top for the whole list; if some of your bare numbers mean minutes and others mean hours, add the unit to those lines.
How do I take out a break?
Put a minus in front of the time: Lunch, -1:00. It comes off the total. Several breaks can go on separate lines, and giving them the same name merges them into one figure. Subtracted entries are excluded from the share calculation, so the percentages describe worked time only.
Is tax taken out of the amount?
No. The amount is hours times rate. Self-employment tax, income tax, expenses and any platform cut all come off after that, and none of them are modeled here. Treat it as the invoice line, not take-home.
Can I use seconds?
Write them as 1:30:45 and they are read. Everything is computed in minutes, so seconds become a fraction of a minute internally and the displayed H:MM hides them. Add several such entries and the displayed values will look a minute off from the total. When seconds matter, read the total-in-minutes figure rather than the H:MM.