Decimal Flight Time Calculator
Turn hours and minutes into tenths for your logbook, work out block time, add up legs and read Hobbs time.
Type 1:25, 1h 25m or 125. Switch the unit to go from decimal back to h:mm.
Type 23:10, 2310 or 11:10 pm. If “in” is earlier than “out”, the flight crossed midnight. Offsets look like +5:30, −4 or 0. Find them in the Zulu time converter.
Night and instrument time are parts of the block time: h:mm (0:40) or decimal (0.7).
Each line can be a time (1:25, 1h 25m, 1.4) or out–in times (0815-1040). Paste straight from a spreadsheet.
Add night and instrument time as more columns: 1:25, 0:40, 0:30 (total, night, instrument). Tabs work too.
Nearest 0.1 and round up are both common logbook and operator practice. No FAA or EASA rule sets one, so use your operator's.
| # | Entered | h:mm | Exact | Logged |
|---|
How your decimal flight time is worked out
Count the minutes, divide by 60, then round to tenths the way your logbook wants.
- 1
Your time
1:25
= 85 min - 2
Divide by 60
85 ÷ 60
= 1.4167 h - 3
Round to tenths
25 min → .4
nearest 0.1 - 4
Log it
1:25
= 1.4 h
Read more: the formula, worked examples, the 6-minute tables and the rules
Pilots log time in hours and tenths of an hour, so 1 hour 25 minutes goes in the logbook as 1.4. A tenth is 6 minutes. This page converts both ways, works out block time from off-blocks and on-blocks times (even across midnight or between time zones), adds up a whole list of legs and reads Hobbs and tach meters. For pay-style hours with breaks and overtime, use the hours calculator. To turn local time into Zulu, use the Zulu time converter.
The formula
exact decimal hours = minutes ÷ 60
nearest tenth = round(minutes ÷ 6) ÷ 10 (3 minutes rounds up)
round up = round minutes ÷ 6 up to a whole number, ÷ 10
round down = round minutes ÷ 6 down to a whole number, ÷ 10
block time = on-blocks (UTC) − off-blocks (UTC), + 24 h if negative
UTC = local time − UTC offset
Hobbs time = end reading − start reading
Worked example
- Convert 1:25: 1 × 60 + 25 = 85 minutes. 85 ÷ 60 = 1.4167 hours exact. 85 ÷ 6 = 14.17, which rounds to 14, so it logs as 1.4. That is 84 minutes, 1 minute less than flown.
- Block time: out 23:10, in 01:35. 01:35 − 23:10 = −21:35, plus 24:00 = 2:25. 145 ÷ 60 = 2.4167 exact; 145 ÷ 6 = 24.17 → 2.4.
- Legs 1:25 + 0:50 + 2:10 + 1:05 = 85 + 50 + 130 + 65 = 330 minutes = 5:30 = 5.5. Rounded one by one they are 1.4 + 0.8 + 2.2 + 1.1 = 5.5 too.
- Hobbs 1436.8 − 1435.2 = 1.6 hours = 1.6 × 60 = 96 minutes = 1:36.
6-minute tables
| Minutes past the hour | Nearest 0.1 | Minutes past the hour | Round up 0.1 |
|---|---|---|---|
| 0–2 | .0 | 0 | .0 |
| 3–8 | .1 | 1–6 | .1 |
| 9–14 | .2 | 7–12 | .2 |
| 15–20 | .3 | 13–18 | .3 |
| 21–26 | .4 | 19–24 | .4 |
| 27–32 | .5 | 25–30 | .5 |
| 33–38 | .6 | 31–36 | .6 |
| 39–44 | .7 | 37–42 | .7 |
| 45–50 | .8 | 43–48 | .8 |
| 51–56 | .9 | 49–54 | .9 |
| 57–59 | 1.0 (next hour) | 55–60 | 1.0 (next hour) |
What the rules say
Under 14 CFR 1.1, flight time is pilot time from when the aircraft moves under its own power for the purpose of flight until it comes to rest after landing, which is why pilots log block to block. 14 CFR 61.51 lists what a logbook must record but does not say how to round. EASA Part-FCL (FCL.010 and FCL.050, Regulation (EU) No 1178/2011) defines flight time for aeroplanes from first moving to take off until finally coming to rest, and covers how it is recorded. The 6-minute tables above are common practice at airlines, Part 135 operators and flight schools, not a regulation, so follow your operator's or school's method and use it every time. Night, under 14 CFR 1.1, runs from the end of evening civil twilight to the beginning of morning civil twilight.
Hobbs and tach
A Hobbs meter runs on clock time once the engine or master is on, and is often used for rental and logbook time. A tach (tachometer) hour meter counts engine revolutions against a set cruise RPM, so at lower power it runs slower and usually shows less time. Maintenance is often tracked on tach time. If a meter rolls over from 9999.9 to 0000.0, the calculator adds 10,000 hours back for you.
Rounding each leg or the total
Adding exact times and rounding once is the most accurate. Some logbooks and operators round every leg, which can add or lose tenths over many short legs. Four 3-minute taxi repositions are 12 minutes (0.2) in total but 0.4 if each is rounded to the nearest tenth. The calculator shows both.
Rule references checked against the eCFR and EASA Easy Access Rules pages linked from the calculator's code. Times are for logbook keeping and training only.
Common questions
How do you convert flight time minutes to tenths of an hour?
Divide the minutes by 60 for the exact decimal, then round to one decimal place. 1 hour 25 minutes is 85 ÷ 60 = 1.42 hours, which logs as 1.4. With the common 6-minute table, 0–2 minutes past the hour is .0, 3–8 is .1, 9–14 is .2 and so on, so 25 minutes is .4.
What is the 6-minute rule for logging flight time?
Each tenth of an hour is 6 minutes, so many pilots and operators log time in steps of 0.1. Some round to the nearest tenth (3–8 minutes = .1), others always round up (1–6 minutes = .1). No FAA or EASA rule sets the method, so use the one your operator or school asks for and stay consistent.
How do I calculate block time across midnight?
Take the off-blocks (out) time from the on-blocks (in) time and add 24 hours if the answer is negative. Out at 23:10 and in at 01:35 gives 01:35 − 23:10 = −21:35, plus 24 hours = 2:25, which is 2.42 hours exact or 2.4 logged. Use UTC for both times, or give each local time its UTC offset.
Should I round each leg or the total?
Rounding each leg and then adding can give a different total from adding the exact times and rounding once. Four 3-minute legs are 12 minutes, which is 0.2 hours, but rounded one by one they are 0.1 each, or 0.4. The calculator shows both so you can match your logbook or operator method.
How do I work out time flown from the Hobbs meter?
Take the Hobbs reading at the start from the reading at the end. 1436.8 − 1435.2 = 1.6 hours, which is 1 hour 36 minutes. The tach usually reads less than the Hobbs because it counts engine revolutions against a set cruise RPM, so a 1.6 Hobbs flight might show 1.3 on the tach.
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