Convert Hours and Minutes to Decimal Hours

The conversion formula

Decimal hours = whole hours + minutes ÷ 60. For 7 hours 30 minutes, calculate 7 + 30 ÷ 60 = 7.50. For 7 hours 45 minutes, the result is 7.75. A time-card notation such as 7:30 is not a decimal number.

Common minute values

15 minutes = 0.25 hours; 20 minutes = approximately 0.33 hours; 30 minutes = 0.50 hours; 45 minutes = 0.75 hours; 50 minutes = approximately 0.83 hours. The repeating fractions are rounded for display, not converted back into working minutes.

Why daily rounding can drift

One minute is approximately 0.02 displayed hours. Seven one-minute entries displayed separately appear to add to 0.14 hours, but the real total is 7 ÷ 60 = approximately 0.12 hours. Mallow Hours adds the original seven minutes and only then formats the decimal total.

Converting back

Multiply the fractional part by 60. For 6.25 hours, 0.25 × 60 = 15 minutes, so the duration is 6 hours 15 minutes. A rounded display such as 6.33 cannot always recover the original minute count exactly. Keep the exported total minutes when precision matters.

Using decimal hours in an invoice

If a checked time card totals 7.50 hours at 20.00 per hour, the basic amount is 150.00. Copy the total and enter it into your invoice deliberately. If you round billable hours or use minimum billing increments, apply the agreement with your customer rather than assuming the calculator has applied it.

What the export preserves

CSV includes total minutes and the two-decimal hours display. Print shows both a readable hours/minutes total and decimal hours. Estimated pay uses the underlying minutes and rounds once to two decimals, so it may differ slightly from multiplying a rounded displayed total.

Continue with a practical example

Open Mallow Hours and choose Try an example. No data is saved until you press Save.

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