How do you add hours and minutes together?

To add times: (1) Convert each time to total seconds or minutes; (2) Add the totals; (3) Convert back. Example: 1:30 + 2:45 → 90 min + 165 min = 255 min = 4:15. Our calculator handles this automatically and shows results in HH:MM:SS, total minutes, and decimal hours.

How do you calculate the difference between two times?

Subtract the start time from the end time. Convert both to total minutes since midnight, then subtract. Example: 9:00 AM to 5:30 PM = (17×60+30) − (9×60) = 1050 − 540 = 510 minutes = 8h 30m. For overnight calculations (e.g., 10 PM to 6 AM), add 24 hours to the end time before subtracting.

What is decimal time and how do you convert it?

Decimal hours express time as a decimal number instead of HH:MM. To convert: decimal = minutes ÷ 60. Examples: 1h 30m = 1.5 hours, 7h 45m = 7.75 hours, 8h 20m = 8.333 hours. Decimal hours are commonly used in payroll systems and billing.

How do you calculate work hours with a break?

Calculate the gross time from start to end, then subtract the break duration. Example: 9:00 AM − 5:30 PM = 8:30 gross. Subtract 30-minute lunch = 8:00 net work hours. Our calculator has a break deduction field in Time Difference mode for this purpose.

How do you handle time that crosses midnight?

For overnight shifts (end time is before start time), add 24 hours to the end time. Example: 10:00 PM to 6:00 AM → treat end as 6:00 AM + 24h = 30:00, then 30:00 − 22:00 = 8 hours. Our Time Difference calculator automatically detects and handles midnight crossovers.

What is the difference between total minutes and decimal hours?

Total minutes counts the complete duration in minutes (e.g., 2h 30m = 150 minutes). Decimal hours expresses the same as a decimal fraction (2.5 hours). Both represent the same duration in different units. Decimal hours are preferred for multiplication (e.g., 8.5 hours × $15/hour = $127.50 pay).

How do I convert between 12-hour and 24-hour (military) time?

12-hour to 24-hour: For AM hours (except 12 AM), the 24-hour equivalent is identical (e.g., 9:00 AM = 09:00). For 12 AM, use 00:00. For PM hours (except 12 PM), add 12 (e.g., 3:30 PM = 15:30). For 12 PM, use 12:00. 24-hour to 12-hour: Hours 0 → 12 AM, 1-11 → 1-11 AM, 12 → 12 PM, 13-23 → 1-11 PM (subtract 12). Military time eliminates AM/PM ambiguity and is the international standard in aviation, medicine and military.

What is ISO 8601 time format?

ISO 8601 is the international standard for date and time: YYYY-MM-DDTHH:MM:SS (e.g., 2026-04-24T15:30:00). The 'T' separates date from time. Optional timezone: 'Z' for UTC or ±HH:MM offset (e.g., 2026-04-24T15:30:00-05:00 for US Eastern). ISO 8601 sorts chronologically as text, avoids DD/MM vs MM/DD ambiguity, and is used across programming, databases, APIs, and international business. Most log files, JSON APIs and calendars default to ISO 8601.

What are the maximum legal working hours in the US, UK, Canada and Australia?

US: No federal daily maximum. Fair Labor Standards Act (FLSA) requires time-and-a-half for non-exempt workers over 40 hours/week. Some states (e.g., California) have stricter daily overtime rules. UK: Working Time Regulations cap average weekly hours at 48 (over 17 weeks), though workers can opt out. Daily rest 11 hours, weekly rest 24 hours. Canada: Canada Labour Code (federal) caps at 48 hours/week, with overtime after 40. Provincial rules vary. Australia: National Employment Standards limit ordinary hours to 38/week plus reasonable additional hours. Awards and enterprise agreements set overtime rates. Always check the specific jurisdiction that applies to your workplace.

How does overtime get calculated differently in each country?

US (FLSA): Overtime = 1.5× regular rate for hours over 40 in a workweek (non-exempt). Some states add daily overtime (e.g., CA: 1.5× over 8 hrs/day, 2× over 12). UK: No statutory overtime premium — pay is set by contract (often same as regular rate). Workers must consent to exceed 48-hour average. Canada: Federal sector pays 1.5× after 40 hours/week or 8 hours/day. Provincial rules differ (Ontario: after 44 hrs/week). Australia: Modern awards typically pay 1.5× first 2-3 overtime hours, 2× after. Shiftworkers and weekend rules add complexity. Enter gross hours into this calculator and apply the relevant multiplier separately.

How does Daylight Saving Time affect time calculations?

DST adds or removes one hour twice a year in countries that observe it (US, UK, most of Canada, parts of Australia). On the 'spring forward' day, the local clock skips an hour — a shift starting before the transition ends one hour earlier in clock time but the same in elapsed time. On 'fall back' day, an hour repeats — a shift can appear to last one hour longer in clock time. For accurate payroll, work in UTC/elapsed time rather than local clock time across DST boundaries. Australia: only some states observe DST (NSW, VIC, SA, TAS, ACT; not QLD, WA, NT).

How do I calculate time across different time zones?

Convert both times to UTC (Coordinated Universal Time) first, then subtract. Each time zone has a UTC offset (e.g., EST = UTC-5, PST = UTC-8, GMT = UTC+0, AEST = UTC+10). Example: 9:00 AM EST to 5:00 PM GMT = 14:00 UTC - 14:00 UTC = 0 hours (same moment). For scheduling meetings across zones, use UTC as the anchor and convert to each participant's local time. ISO 8601 with offset (e.g., 2026-04-24T09:00-05:00) removes all ambiguity.

How do I calculate billable hours for consulting or legal work?

Most billing uses decimal hours (e.g., 2.5 hours instead of 2:30). Track start and end times, subtract any non-billable breaks, convert to decimal, then multiply by your rate. Example: 9:00 AM to 1:15 PM minus 15-minute break = 4:00 net = 4.0 decimal hours × $150/hr = $600. For partial-hour billing, many firms round to the nearest 6 minutes (0.1 hour) or 15 minutes (0.25 hour) per standard legal billing practices. Our calculator outputs decimal hours alongside HH:MM:SS automatically.

How accurate are online time calculators?

For integer seconds, online time calculators are exact — the math is base-60 arithmetic with no floating-point imprecision at the second level. Decimal hours involve division (e.g., 20 min / 60 = 0.3333...), which browsers truncate at 15-17 significant digits — plenty for payroll, scheduling, and billing. Edge cases: leap seconds (occasional 1-second insertions in UTC by the International Earth Rotation Service) are not typically accounted for in web calculators, but they only matter for astronomy, GPS and scientific timing, not daily use. DST transitions are handled by treating times as unadjusted wall-clock unless the calculator explicitly asks for a time zone.

calculate

Time Calculator

calculators.im ↗

timer Time Range

Start Time

End Time

Break / Lunch (minutes)

Quick Examples

calculate Result

Duration

8h 30m

HH:MM:SS = 8:30:00

Total Minutes

510

Decimal Hours

8.5

Net Work Time (after break)

8:00:00

Minutes: 480 Decimal: 8

schedule Time Conversions

Decimal Hours

hours = minutes ÷ 60

To Hours:Mins

1.5h = 1h 30m

Total Seconds

H×3600 + M×60 + S

AM/PM → 24h

PM (not 12): +12h

Midnight Cross

End < Start → +24h

payments Common Decimal Hours

15 min = 0.25 h

30 min = 0.5 h

45 min = 0.75 h

1h 20m = 1.333 h

7h 30m = 7.5 h

8h 45m = 8.75 h

lightbulb Quick Tips

•Enter 9:00 AM or 09:00 — both work
•Add break minutes for net payroll hours
•Overnight: 10 PM to 6 AM = 8 hours
•Decimal × hourly rate = pay amount
•Add mode: total up multiple work blocks