Build a top-to-bottom expression by mixing addition, subtraction, multiplication, and division. Paste any duration format—such as HH:MM:SS, 1h 32m, 95m, or 5400s—and apply factors like 2.5 or 3/2. Results update instantly with matching HH:MM:SS, decimal hours, and decimal minutes outputs.
Digital
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Decimal Hours
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Decimal Minutes
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Show Calculation Steps
Add values above to see step-by-step math.
Row Breakdown
| Row | Operator | Entered | Result (Digital) | Result (Hours) | Result (Minutes) |
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Time Calculator – Add, Subtract, Multiply & Divide Time
Add, subtract, multiply, or divide durations in a running expression. Compare digital time with decimal hours and minutes, review the steps, and export a CSV.
Two colon fields mean hours and minutes; bare numbers mean seconds.
Evaluate the rows in order
The arithmetic time calculator starts with the first duration, then applies each row from top to bottom. It does not use multiplication-before-addition precedence. For example, 1:00 + 00:30 × 2 produces 3 hours: first add 30 minutes, then double the running total.
Add and subtract rows take durations. Multiply and divide rows take unitless factors, including fractions such as 3/2. A zero divisor produces an error. Use the Steps panel to compare each running total with the original input.
Use Average Time for a mean, or Time Duration to subtract clock readings.
Choose an unambiguous duration format
Two colon fields mean HH:MM; three mean HH:MM:SS; four mean DD:HH:MM:SS. Hours can exceed 23 because these are durations. Unit text such as 1h 30m, 5.25h, 5400s, and 250ms is also accepted. A bare number means seconds, so write 1.5h when you mean one and a half hours.
Place a minus sign before the whole duration for a negative value. Blank later rows are skipped; a missing first duration prevents a result. Correct a row with an error before copying or exporting. This is elapsed-time math: no dates, time zones, or daylight-saving transitions are inferred.
Import, paste, and export
Use Add Row for another operation, or paste one operation per line in bulk mode. CSV import accepts a simple operator,value layout with an optional operator,value or operator,input header. Download CSV Template supplies a working example. Quoted fields containing commas are not a supported CSV dialect.
Export CSV downloads time-arithmetic-expression.csv with the entered value and running results in digital time, hours, and minutes. This page does not export an Excel workbook or an error-only file. Processing runs on the browser's main thread; no row-count or speed guarantee is made.
Display precision and negative totals
Decimal hours and minutes use 0–6 decimal places with nearest, up, down, or banker's rounding. The digital display is calculated separately at millisecond precision. Turning milliseconds off hides that part; it does not apply the decimal rounding rule to digital time.
Clamp negative changes a negative final total to zero. It does not change the intermediate Steps or determine a payroll rule. For example, 1:00 − 1:30 produces −00:30:00, or 00:00:00 with Clamp negative enabled. Preserve the original inputs when comparing adjustments.
Share link includes rows, dec, round, clamp, and fmt in its query string. Anyone receiving the link can read those inputs. Parameter URLs remain views of this calculator and use the same canonical page.