A worked example: an 8-pomodoro session in seconds
The pomodoro timer's formula gives an 8-pomodoro session at the classic 25/5/15 pattern (long break every 4th pomodoro) a total duration of 245 minutes. Multiplying by 60 turns that into 14,700 seconds, and running that number through the seconds calculator's formula returns 4 hours, 5 minutes, and 0 seconds — with decimal totals of 245 total minutes and 4.0833 total hours. The h:m:s result, "4h 5m 0s," matches the pomodoro timer's own formatted output of "4h 5m" exactly, because both calculators are describing the same 245 minutes.
The formula: minutes out of one calculator, seconds into the other
The chain has two steps. First, the pomodoro timer computes totalDurationMinutes as (pomodoros × work minutes) + (short breaks × short break length) + (long breaks × long break length). Second, that total is converted to seconds (minutes × 60) and handed to the seconds calculator, which applies hours = floor(seconds ÷ 3600), minutes = floor((seconds mod 3600) ÷ 60), and seconds = seconds mod 60. Because 245 minutes converts to a whole number of seconds (14,700) with no remainder below the minute mark, the seconds figure in the final breakdown always comes out to 0 for a pomodoro session — the pomodoro formula never produces fractional minutes finer than hundredths, and multiplying by 60 keeps that exact.
A second chain: 12 pomodoros of deep work
The 12-pomodoro deep-work session (50-minute work blocks, 10-minute short breaks, 20-minute long breaks, long break every 3rd pomodoro) has a total duration of 740 minutes from the pomodoro timer's formula. Converting to seconds gives 740 × 60 = 44,400 seconds, and the seconds calculator breaks that down into 12 hours, 20 minutes, and 0 seconds — with totals of 740 total minutes and 12.3333 total hours. Again the h:m:s result lines up with the pomodoro timer's own "12h 20m" label.
Why chaining calculators catches unit mistakes
Running a pomodoro total through the seconds calculator is a useful sanity check: if the two calculators' formatted durations ever disagreed — say the pomodoro timer said "4h 5m" but the seconds breakdown of the same total came out to something else — that would flag a unit conversion bug rather than a planning mistake. Because minutes-to-seconds is just a ×60 multiplication with nothing to round away, the two independent formulas agreeing on "4h 5m" and "12h 20m" confirms both are handling the underlying duration consistently.