09:00 to 17:00 with a 30 minute unpaid break is 7 hours 30 minutes, which is 7.50 decimal hours, or 450 minutes.
No black box. Four short rules, and the tool shows you the same arithmetic on your own numbers.
Finish time minus start time, minus unpaid breaks. Take 09:00 from 17:00 and you have 8 hours, which is 480 minutes. Take off a 30 minute unpaid lunch and you have worked 7 hours 30 minutes, or 450 minutes. Only unpaid breaks come off. A paid break is still working time and stays in.
To take 08:45 from 17:30 by hand you cannot do 30 minus 45, so you borrow an hour and treat 17:30 as 16 hours and 90 minutes. Then 90 minus 45 is 45 minutes, and 16 minus 8 is 8 hours, giving 8 hours 45 minutes. Working in total minutes avoids the borrowing altogether, which is exactly what this calculator does.
Divide the minutes by 60. So 30 minutes is 0.50, 45 minutes is 0.75 and 20 minutes is 0.33. Payroll and billing systems almost always want decimal hours, not hours and minutes.
If the finish is earlier than the start, the shift has crossed into the next day, so add 24 hours before taking the start away. From 22:00 to 06:00 is 2 hours to midnight plus 6 hours after it, which is 8 hours. Record it against the day it started, or the hours get counted twice at one end of the week and missed at the other.
Three tables, no arithmetic needed. Every row has a Try it button that loads that shift into the calculator above. Figures assume no break unless the column says otherwise.
| Shift | 24 hour | No break | Less 30 minutes | Less 1 hour | Try it |
|---|---|---|---|---|---|
| 9am to 5pm | 09:00 to 17:00 | 8h 00m (8.00) | 7h 30m (7.50) | 7h 00m (7.00) | |
| 8am to 4pm | 08:00 to 16:00 | 8h 00m (8.00) | 7h 30m (7.50) | 7h 00m (7.00) | |
| 8am to 4:30pm | 08:00 to 16:30 | 8h 30m (8.50) | 8h 00m (8.00) | 7h 30m (7.50) | |
| 7am to 3:30pm | 07:00 to 15:30 | 8h 30m (8.50) | 8h 00m (8.00) | 7h 30m (7.50) | |
| 8:30am to 5pm | 08:30 to 17:00 | 8h 30m (8.50) | 8h 00m (8.00) | 7h 30m (7.50) | |
| 9am to 5:30pm | 09:00 to 17:30 | 8h 30m (8.50) | 8h 00m (8.00) | 7h 30m (7.50) | |
| 8:30am to 5:30pm | 08:30 to 17:30 | 9h 00m (9.00) | 8h 30m (8.50) | 8h 00m (8.00) | |
| 9am to 6pm | 09:00 to 18:00 | 9h 00m (9.00) | 8h 30m (8.50) | 8h 00m (8.00) | |
| 10am to 6pm | 10:00 to 18:00 | 8h 00m (8.00) | 7h 30m (7.50) | 7h 00m (7.00) | |
| 6am to 2pm | 06:00 to 14:00 | 8h 00m (8.00) | 7h 30m (7.50) | 7h 00m (7.00) |
| Shift | 24 hour | No break | Less 30 minutes | Less 1 hour | Try it |
|---|---|---|---|---|---|
| 10pm to 6am | 22:00 to 06:00 | 8h 00m (8.00) | 7h 30m (7.50) | 7h 00m (7.00) | |
| 11pm to 7am | 23:00 to 07:00 | 8h 00m (8.00) | 7h 30m (7.50) | 7h 00m (7.00) | |
| 9pm to 5am | 21:00 to 05:00 | 8h 00m (8.00) | 7h 30m (7.50) | 7h 00m (7.00) | |
| 6pm to 2am | 18:00 to 02:00 | 8h 00m (8.00) | 7h 30m (7.50) | 7h 00m (7.00) | |
| 9pm to 5:30am | 21:00 to 05:30 | 8h 30m (8.50) | 8h 00m (8.00) | 7h 30m (7.50) | |
| 8pm to 6am | 20:00 to 06:00 | 10h 00m (10.00) | 9h 30m (9.50) | 9h 00m (9.00) | |
| 7pm to 7am | 19:00 to 07:00 | 12h 00m (12.00) | 11h 30m (11.50) | 11h 00m (11.00) |
| Week | Days | Per day |
|---|---|---|
| 35 hours | 5 days | 7h 00m (7.00) |
| 37.5 hours | 5 days | 7h 30m (7.50) |
| 40 hours | 5 days | 8h 00m (8.00) |
| 42.5 hours | 5 days | 8h 30m (8.50) |
| 45 hours | 5 days | 9h 00m (9.00) |
| 30 hours | 4 days | 7h 30m (7.50) |
| 40 hours | 4 days | 10h 00m (10.00) |
Not in the tables? Put your own times into the calculator above and it will work them out.
Timesheets and fee invoices are kept in decimal hours, not in hours and minutes. Divide the minutes by 60 and you have it.
| Minutes | Decimal hours |
|---|---|
| 0 minutes | 0.00 |
| 5 minutes | 0.08 |
| 10 minutes | 0.17 |
| 15 minutes | 0.25 |
| 20 minutes | 0.33 |
| 25 minutes | 0.42 |
| 30 minutes | 0.50 |
| 35 minutes | 0.58 |
| 40 minutes | 0.67 |
| 45 minutes | 0.75 |
| 50 minutes | 0.83 |
| 55 minutes | 0.92 |
| 60 minutes | 1.00 |
| Hours and minutes | Decimal hours |
|---|---|
| 1 hour 15 minutes | 1.25 |
| 1 hour 30 minutes | 1.50 |
| 1 hour 45 minutes | 1.75 |
| 2 hours 20 minutes | 2.33 |
| 7 hours 30 minutes | 7.50 |
Six minutes is exactly a tenth of an hour, which is why so many firms record time in six minute units. Every entry then lands on a clean tenth. Set the calculator above to six minute units and you can see what your own entries become.
| Minutes | Decimal hours |
|---|---|
| 6 minutes | 0.1 |
| 12 minutes | 0.2 |
| 18 minutes | 0.3 |
| 24 minutes | 0.4 |
| 30 minutes | 0.5 |
| 36 minutes | 0.6 |
| 42 minutes | 0.7 |
| 48 minutes | 0.8 |
| 54 minutes | 0.9 |
| 60 minutes | 1.0 |
7.30 means 7 hours plus 0.30 of an hour. Multiply 0.30 by 60 and you get 18 minutes, so 7.30 is 7 hours 18 minutes. Seven and a half hours is written 7.50. Getting these the wrong way round costs 12 minutes on every single entry, and it is the most common timesheet mistake there is. The calculator shows both figures side by side, so the mistake cannot be made.
What you should take off a timesheet, and what the rules actually say.
Under the Working Time Regulations 1998, a worker aged 18 or over whose daily working time is more than 6 hours is entitled to an uninterrupted rest break of at least 20 minutes, taken during the day rather than bolted onto the start or the end of it. Workers under 18 are entitled to 30 minutes once they work more than 4 and a half hours. Many employers give more than the minimum in their own contracts.
There is no legal requirement for a rest break to be paid, so whether yours is paid is a matter for your contract of employment. Deduct a break only if it is unpaid and you are genuinely free of duties during it, because that time is not working time. A paid break stays in the total, and so does time when you have to remain available, such as staying on site to take calls. If your break is paid, put 0 in the break box.
Average weekly working time is normally capped at 48 hours, measured across a 17 week reference period rather than week by week, and an adult worker can agree in writing to opt out and can withdraw that agreement later. A single long week is not automatically a breach, but it is worth being able to see one, which is what a running weekly total gives you. The week tab flags a total over 48 hours so you know when an average is worth checking.
General information about UK working time rules, and not legal advice. Check your own contract and the current government guidance, or take advice, for your own situation.
Rounding looks like a rounding error. Over a year, on a fee earning team, it is not.
Recording to the nearest minute is not rounding at all and is the only setting with no cost attached. Six minute units give tenths of an hour and suit work billed in tenths. Quarter hours suit longer blocks of design or site work. Pick one unit for everybody and stay with it.
Rounding to the nearest unit is even handed, because entries land above and below the line about equally often. A one way rule is not. Always rounding up will not survive a client query. Always rounding down quietly gives work away and under-records the hours people actually worked. Whichever you choose, write the rule down and apply it the same way to every entry and every person.
Six minutes of drift on one 8 hour shift at £85 an hour is £8.50, which is easy to shrug off. Now scale it. Take six entries a day, each rounded down to the nearest quarter hour and losing an average of 7 minutes: that is 42 minutes a day, 0.7 of an hour. Across five days a week and 45 chargeable weeks that is 157.5 hours a year, which at £85 an hour is £13,387.50 for one fee earner.
| Exact | To 6 minutes | To 15 minutes |
|---|---|---|
| 7h 22m | 7h 24m (7.40) | 7h 15m (7.25) |
| 7h 28m | 7h 30m (7.50) | 7h 30m (7.50) |
| 3h 07m | 3h 06m (3.10) | 3h 00m (3.00) |
| 1h 52m | 1h 54m (1.90) | 1h 45m (1.75) |
Set the direction in the calculator above to Always down and it does that sum on your own unit, your own rate and your own times. That is the cost of rounding hours you did write down. The cost of the hours nobody writes down at all is a bigger and separate question, and the timesheet ROI calculator estimates it across a whole team over a year.
Working out the hours is the easy half. Knowing which of them reach an invoice is where the money is.
Hours worked covers everything you spent on the job, including admin, travel, internal reviews, training and business development. Chargeable hours are the part a client agreed to pay for. The two are never the same number, and the gap is not waste, but it does need to be known rather than guessed at.
Divide chargeable hours by hours worked. Six chargeable hours in a 7 hour 30 minute day is 80 per cent. The figure only means anything if the hours behind it were recorded when the work happened rather than reconstructed from memory on a Friday afternoon. Quantim lets you set up billable and non billable activities so administration is separated from project work, and its time tracking reports compare billable against non billable time and assess staff utilisation across the team.
Once hours sit against the right job, stage, task and person, an invoice is an extract rather than a rebuild. Quantim generates invoices directly from the data already captured in your projects, so nothing is typed twice and nothing quietly drops out between the timesheet and the bill. You can watch that happen step by step in the timesheet to invoice walkthrough.
This page does one day or one week for one person. Quantim does it for everybody, on every job, every week, and turns the answer into a fee invoice.
Log each day's work against jobs and activities while it is still fresh. The detail-first option.
Batch the week in one grid for people who prefer a single sitting. Same accuracy, different rhythm.
Hour-by-hour recording for the projects where precise job costing matters most.
Hit start when work begins and stop when it ends, and Quantim works out the hours for you.
Just say it out loud. AI turns spoken work into a structured timesheet entry.
One account, every screen. Time logged on site syncs instantly with the office.
iOS & Android app for logging on site, between meetings, or on the move.
The full web platform in any browser with nothing to install, plus every report and dashboard at your desk.
Android and iOS watch logging. Hours from your wrist.
Quantim is built for UK professional services firms that sell their time: architects, engineers, interior designers, surveyors, EPC contractors, IT consultants and property developers.
Every one of these is free, needs no signup, and works its answer out in your browser. Nothing you type is saved or sent anywhere.
See what unrecorded billable hours cost your practice over a year, and what capturing them could recover. Includes a charge-out rate and margin calculator.
Open the ROI calculator →Measure chargeable utilisation against the capacity you actually have, then size the gap to your target in hours first and fees second.
Open the utilisation calculator →Play through the whole flow: log time against a job, review the fees it earns, then raise the fee invoice. No signup, nothing to install.
Open the demo →Enter your hourly rate, contracted hours and overtime hours at your contract multiplier and see gross overtime pay, effective hourly rate and the annual cost.
Open the overtime calculator →You have just worked out one day. Quantim does it for every person, every job and every week, and turns the result into a fee invoice. Try it free for a month.
Free for 1 month · No credit card required · UK-based support