Guides › Calculating conversions
How to calculate time-and-a-half and double time
Converting overtime into time off is arithmetic, but it goes wrong constantly — usually because people mix hours and minutes, or because the rate that applies to a given shift was never agreed. Here is the method, then the examples.
Step 1: convert the shift to decimal hours
Minutes divided by 60 give the decimal fraction. This is the single most common source of errors: 3 hours 30 minutes is 3.5 hours, not 3.3.
- 15 minutes = 0.25
- 20 minutes = 0.33
- 30 minutes = 0.5
- 45 minutes = 0.75
So a shift from 08:30 to 12:00 is 3 hours 30 minutes, or 3.5 decimal hours. A shift from 17:15 to 22:00 is 4 hours 45 minutes, or 4.75 hours.
Step 2: apply the conversion multiplier
Time off earned = decimal hours worked × multiplier.
- 1:1 (hour for hour) — multiplier 1.0. Standard for ordinary weekday overtime.
- Time and a half — multiplier 1.5. Typically weekends or unsocial hours.
- Double time — multiplier 2.0. Typically public holidays and emergency call-outs.
- Day for day — a full extra day worked earns one full day off, whatever the exact hours. Simple, but it can be generous for short days and harsh for long ones.
Conversion table
| Worked | Decimal | At 1:1 | At 1.5x | At 2x |
|---|---|---|---|---|
| 2:00 | 2.0 | 2h 0m | 3h 0m | 4h 0m |
| 3:30 | 3.5 | 3h 30m | 5h 15m | 7h 0m |
| 4:45 | 4.75 | 4h 45m | 7h 8m | 9h 30m |
| 6:00 | 6.0 | 6h 0m | 9h 0m | 12h 0m |
| 8:00 | 8.0 | 8h 0m | 12h 0m | 16h 0m |
| 10:15 | 10.25 | 10h 15m | 15h 23m | 20h 30m |
Worked example: a Sunday morning
An employee works 08:30 to 12:00 on a Sunday. That is 3.5 hours. The employer's policy credits weekend work at time and a half: 3.5 × 1.5 = 5.25 hours, which is 5 hours 15 minutes of time off in lieu.
Worked example: a night shift crossing midnight
An employee starts at 21:00 and finishes at 02:30 the next morning. Do not subtract the clock times directly — that gives a nonsensical negative. Split the shift instead: 21:00 to 24:00 is 3 hours, 00:00 to 02:30 is 2.5 hours, giving 5.5 hours total. At double time for the public-holiday portion that is 11 hours of TOIL. (TimerOff handles this with a "shift ends the next day" toggle, so the maths is done for you.)
Worked example: converting a balance into days
Balances are easier to hold in hours and easier to use in days. Divide by the employee's contracted day length — not by 8 unless 8 is genuinely their day. For a 7.5-hour day, a balance of 22.5 hours is exactly 3 days. For an 8-hour day, 22.5 hours is 2 days and 6.5 hours, which is why TimerOff shows both the raw hours and the day equivalent.
Rounding and part hours
Pick one rounding rule and write it into your policy. Common choices are to the nearest 15 minutes (0.25), to the nearest 6 minutes (0.1), or no rounding at all. Whichever you choose, apply it consistently and always in the same direction — rounding down in the employer's favour every time is the fastest way to lose trust in the whole scheme. TimerOff stores exact decimal hours and rounds only for display.
Don't forget the deduction side
Conversion applies to hours earned. Hours used are always deducted at 1:1 — a booked half day of 4 hours removes exactly 4 hours from the balance, regardless of what multiplier created those hours. Applying the multiplier a second time on the way out is a surprisingly common spreadsheet bug.
See the rules in action in how TimerOff works, or set your own rates with the policy template.