# Automatic time calculation **URL:** \ **Category:** Users\ **Created:** [April 13, 2014, 2:33pm UTC](https://forum.dimagi.com/t/automatic-time-calculation/1704 "2014-04-13T14:33:23Z")\ **Posts on this page:** 20\ **Page:** 1
**Author:** ![Ameera\_Hamid](https://dimagi.b-cdn.net/letter_avatar_proxy/v4/letter/a/e8c25b/32.png) [@Ameera\_Hamid](https://forum.dimagi.com/u/Ameera_Hamid)\ **Post date:** [April 13, 2014, 2:33pm UTC](https://forum.dimagi.com/t/automatic-time-calculation/1704/1 "2014-04-13T14:33:23Z")
Hi Everyone, I am working on an electronic logbook for my first year students. in the logbook there is a clock-in / clock-out module which contains forms to clock in for the day and clock out at the end of the day. I would like to calculate the hours and mins that they have worked and display it on the clock out form when they are clocking out. I have seen commcare documentation to support calculations using dates, but I am unsure of how to calculate hours and minutes using time. is there a calculation/logic for that? Any help would be greatly appreciated! Thanks, Ameera ---
**Author:** ![Clayton\_Sims](https://dimagi.b-cdn.net/user_avatar/forum.dimagi.com/clayton_sims/32/496_2.png) [@Clayton\_Sims](https://forum.dimagi.com/u/Clayton_Sims)\ **Post date:** [April 15, 2014, 7:11pm UTC](https://forum.dimagi.com/t/automatic-time-calculation/1704/2 "2014-04-15T19:11:16Z")
Ameera, You can use the "now()" function to get the current date and time. To use the result it in calculations, you must convert it to a decimal value using the "double()" function. The double function will convert the now() value to a number that represents the date/time in days. This is similar to doing calculations on dates, when you use int() to convert a date value into number of days. When the user "checks in" in you can capture the full date and time with a hidden value with a calculation: double(now()) Save the hidden value to the case. When the user "checks out" you can load that value into the "checks out" form (I'll call the hidden value 'log\_in\_time'). Create another hidden value (I'll call it 'time\_worked') represent the amount of time that has passed, by calculating: double(now()) - double(/data/log\_in\_time) The result is a decimal value in days/fractions of days. To convert to hours and minutes, you can do the following calculations: int(/data/time\_worked \* 24) = (rounded down) the # of hours int(((/data/time\_worked\*24) - int(/data/time\_worked \* 24)) \* 60) = (rounded down) the # of minutes worked. I know that's a little bit complex. Please let me know if you need a hand testing anything out or getting this to work. -Clayton > **···** > > On Sun, Apr 13, 2014 at 10:33 AM, Ameera Hamid wrote: > > > Hi Everyone, > > > > I am working on an electronic logbook for my first year students. in the > > logbook there is a clock-in / clock-out module which contains forms to > > clock in for the day and clock out at the end of the day. I would like to > > calculate the hours and mins that they have worked and display it on the > > clock out form when they are clocking out. I have seen commcare > > documentation to support calculations using dates, but I am unsure of how > > to calculate hours and minutes using time. is there a calculation/logic > > for that? > > > > Any help would be greatly appreciated! > > > > Thanks, > > Ameera > > > > -- > > You received this message because you are subscribed to the Google Groups > > "commcare-users" group. > > To unsubscribe from this group and stop receiving emails from it, send an > > email to [commcare-users+unsubscribe@googlegroups.com](mailto:commcare-users+unsubscribe@googlegroups.com). > > For more options, visit [https://groups.google.com/d/optout](https://groups.google.com/d/optout). ---
**Author:** ![Ameera\_Hamid](https://dimagi.b-cdn.net/letter_avatar_proxy/v4/letter/a/e8c25b/32.png) [@Ameera\_Hamid](https://forum.dimagi.com/u/Ameera_Hamid)\ **Post date:** [April 16, 2014, 7:51am UTC](https://forum.dimagi.com/t/automatic-time-calculation/1704/3 "2014-04-16T07:51:37Z")
Thanks Clayton, I'm going to test it out and will let you know if i need more assistance. Kind regards, Ameera > **···** > > On Sunday, 13 April 2014 16:33:23 UTC+2, Ameera Hamid wrote: \> \> Hi Everyone, \> \> I am working on an electronic logbook for my first year students. in the \> logbook there is a clock-in / clock-out module which contains forms to \> clock in for the day and clock out at the end of the day. I would like to \> calculate the hours and mins that they have worked and display it on the \> clock out form when they are clocking out. I have seen commcare \> documentation to support calculations using dates, but I am unsure of how \> to calculate hours and minutes using time. is there a calculation/logic \> for that? \> \> Any help would be greatly appreciated! \> \> Thanks, \> Ameera \> ---
**Author:** ![JayH](https://dimagi.b-cdn.net/letter_avatar_proxy/v4/letter/j/6a8cbe/32.png) [@JayH](https://forum.dimagi.com/u/JayH)\ **Post date:** [May 17, 2019, 9:38am UTC](https://forum.dimagi.com/t/automatic-time-calculation/1704/4 "2019-05-17T09:38:30Z")
> [@Clayton\_Sims](#): > > int(((/data/time\_worked\*24) - int(/data/time\_worked \* 24)) \* 60) Hi Clayton, I am working on this exact calculation in Commcare but its not working. What i want to capture is the time taken for a coaching session, see steps i took below: We have two time questions, one for start\_time and the other for end\_time hidden value(debut) = double(start\_time) hidden value(fin) = double(end\_time) hidden value(coaching\_time) = hidden value(fin) - hidden value(debut) //should i be converting before subtracting? hidden value(convert\_time) = int(((coaching\_time \* 24) \*60)) Label : The total coaching time is : hidden value(convert\_time) I keep getting zero as an answer. please advise. ---
**Author:** ![Clayton\_Sims](https://dimagi.b-cdn.net/user_avatar/forum.dimagi.com/clayton_sims/32/496_2.png) [@Clayton\_Sims](https://forum.dimagi.com/u/Clayton_Sims)\ **Post date:** [May 17, 2019, 3:32pm UTC](https://forum.dimagi.com/t/automatic-time-calculation/1704/5 "2019-05-17T15:32:36Z")
Hi, Have you tried seeing what the intermediate value of each of those calculations is? The [Data Preview "Evaluate XPath" tool](https://confluence.dimagi.com/display/commcarepublic/Web+Apps+Data+Preview) is very helpful for trying different calculations and seeing what the results are piece by piece to break down where issues are occuring. Specifically: > We have two time questions, one for start\_time and the other for end\_time > hidden value(debut) = double(start\_time) > hidden value(fin) = double(end\_time) I'm not sure that this is producing the result you might be hoping for, as I'm not sure that Time entry questions actual convert helpfully to numbers automatically. -Clayton ---
**Author:** ![JayH](https://dimagi.b-cdn.net/letter_avatar_proxy/v4/letter/j/6a8cbe/32.png) [@JayH](https://forum.dimagi.com/u/JayH)\ **Post date:** [May 19, 2019, 4:31am UTC](https://forum.dimagi.com/t/automatic-time-calculation/1704/6 "2019-05-19T04:31:13Z")
Hi @Clayton_Sims, My web apps view doesn't show me all the applications within my project space for me to test my expressions. Is there something i can do to rectify this? ---
**Author:** ![Clayton\_Sims](https://dimagi.b-cdn.net/user_avatar/forum.dimagi.com/clayton_sims/32/496_2.png) [@Clayton\_Sims](https://forum.dimagi.com/u/Clayton_Sims)\ **Post date:** [May 20, 2019, 2:39pm UTC](https://forum.dimagi.com/t/automatic-time-calculation/1704/7 "2019-05-20T14:39:10Z")
Hi Jumai, You should be able to see the Data Preview pane in Live Preview as well as in Web Apps. Do you see the blue bar at the bottom of the Live Preview pane? -Clayton ---
**Author:** ![JayH](https://dimagi.b-cdn.net/letter_avatar_proxy/v4/letter/j/6a8cbe/32.png) [@JayH](https://forum.dimagi.com/u/JayH)\ **Post date:** [May 20, 2019, 6:19pm UTC](https://forum.dimagi.com/t/automatic-time-calculation/1704/8 "2019-05-20T18:19:41Z")
Hi Clayton, Can you please send images to help me identify these features? Is the image below what you are referring to ? ![image](https://dimagi.b-cdn.net/images/transparent.png) ---
**Author:** ![Clayton\_Sims](https://dimagi.b-cdn.net/user_avatar/forum.dimagi.com/clayton_sims/32/496_2.png) [@Clayton\_Sims](https://forum.dimagi.com/u/Clayton_Sims)\ **Post date:** [May 20, 2019, 7:24pm UTC](https://forum.dimagi.com/t/automatic-time-calculation/1704/9 "2019-05-20T19:24:31Z")
Hi, Within Live Preview you'd see the Data Preview Pane as a floating button on the lower right hand portion of the UI as in the screenshot below, underneath the "Submit" button ![image.png](https://dimagi.b-cdn.net/uploads/default/original/1X/3d719be433089aa196284817ad1357e799e7a80b.png) -Clayton ---
**Author:** ![JayH](https://dimagi.b-cdn.net/letter_avatar_proxy/v4/letter/j/6a8cbe/32.png) [@JayH](https://forum.dimagi.com/u/JayH)\ **Post date:** [May 20, 2019, 7:33pm UTC](https://forum.dimagi.com/t/automatic-time-calculation/1704/10 "2019-05-20T19:33:21Z")
Okay, Seen. Unfortunately the expressions aren't working. Does that mean the only option would be to do this after extracting the data from Commcare? ![image](https://dimagi.b-cdn.net/images/transparent.png) ---
**Author:** ![Clayton\_Sims](https://dimagi.b-cdn.net/user_avatar/forum.dimagi.com/clayton_sims/32/496_2.png) [@Clayton\_Sims](https://forum.dimagi.com/u/Clayton_Sims)\ **Post date:** [May 20, 2019, 11:15pm UTC](https://forum.dimagi.com/t/automatic-time-calculation/1704/11 "2019-05-20T23:15:35Z")
The other option would be to manipulate the times using the [substring-before() and substring-after() functions](https://confluence.dimagi.com/display/commcarepublic/CommCare+Functions#CommCareFunctions-substring-before) to make your own integer representations of the times that are entered IE: int(substring-before(#form/timestart, ":")) \* 60 + int(substring-after(#form/timestart, ":")) would in theory produce a number of minutes that could be subtracted from a similar calculation for a "time of end", but that wouldn't properly calculate for times that 'wrap around' (IE: 11:30pm -\> 1:30am) or other edge cases. -Clayton ---
**Author:** ![JayH](https://dimagi.b-cdn.net/letter_avatar_proxy/v4/letter/j/6a8cbe/32.png) [@JayH](https://forum.dimagi.com/u/JayH)\ **Post date:** [May 22, 2019, 2:57pm UTC](https://forum.dimagi.com/t/automatic-time-calculation/1704/12 "2019-05-22T14:57:46Z")
> [@Clayton\_Sims](#): > > )) \* 60 + int(substring-after(#form/timestart, “:”)) Unfortunately that still doesn't work for me, it doesn't seem to be parsing anything. ![image](https://dimagi.b-cdn.net/images/transparent.png) int(substring-before(#form/start\_time, ':')) \* 60 + int(substring-after(#form/start\_time, ':')) int(substring-before(#form/end\_time, ':')) \* 60 + int(substring-after(#form/end\_time, ':')) ---
**Author:** ![Clayton\_Sims](https://dimagi.b-cdn.net/user_avatar/forum.dimagi.com/clayton_sims/32/496_2.png) [@Clayton\_Sims](https://forum.dimagi.com/u/Clayton_Sims)\ **Post date:** [May 22, 2019, 5:57pm UTC](https://forum.dimagi.com/t/automatic-time-calculation/1704/13 "2019-05-22T17:57:56Z")
It's surprising to me that those expressions would ever be blank, I'd expect them to produce errors, "NaN", or '0' as an output if something wasn't right. It would help to split up those expressions to try to pinpoint what parts of them are not producing the expected result. ---
**Author:** ![Ethan\_Soergel](https://dimagi.b-cdn.net/user_avatar/forum.dimagi.com/ethan_soergel/32/543_2.png) [@Ethan\_Soergel](https://forum.dimagi.com/u/Ethan_Soergel)\ **Post date:** [May 22, 2019, 6:48pm UTC](https://forum.dimagi.com/t/automatic-time-calculation/1704/14 "2019-05-22T18:48:45Z")
Hi Jay, Have you tried out the "Evaluate XPath" feature of Data Preview? In your screenshots, there is a "Menu" option in the top right. If you click that, you should see an option called "Evaluate XPath", which will take you to a screen where you can try out various expressions on the form without needing to reload everything each time. This should make it pretty quick to test out each part of those expressions to see where it's going wrong. Note that instead of `#form/timestart`, you'll need to reference `/data/timestart`, as that `#form` syntax only works in the form builder. ---
**Author:** ![JayH](https://dimagi.b-cdn.net/letter_avatar_proxy/v4/letter/j/6a8cbe/32.png) [@JayH](https://forum.dimagi.com/u/JayH)\ **Post date:** [May 23, 2019, 10:56am UTC](https://forum.dimagi.com/t/automatic-time-calculation/1704/15 "2019-05-23T10:56:48Z")
Hi @Ethan_Soergel, @Clayton_Sims, Been trying out the expressions using the Evaluate XPath feature but it still doesn't seem to understand the expression. ![image](https://dimagi.b-cdn.net/images/transparent.png) ---
**Author:** ![Ethan\_Soergel](https://dimagi.b-cdn.net/user_avatar/forum.dimagi.com/ethan_soergel/32/543_2.png) [@Ethan\_Soergel](https://forum.dimagi.com/u/Ethan_Soergel)\ **Post date:** [May 23, 2019, 1:16pm UTC](https://forum.dimagi.com/t/automatic-time-calculation/1704/16 "2019-05-23T13:16:13Z")
Ah, that's the problem - it should be `/data/start_time`, not `#data/start_time`. The expression tester doesn't support easy references. Additionally, the `substring-before` function takes two arguments. You can read more about it [here](https://confluence.dimagi.com/display/commcarepublic/CommCare+Functions#CommCareFunctions-substring-before). I believe the expression should be ```auto int(substring-before(/data/timestart, “:”)) ``` ---
**Author:** ![JayH](https://dimagi.b-cdn.net/letter_avatar_proxy/v4/letter/j/6a8cbe/32.png) [@JayH](https://forum.dimagi.com/u/JayH)\ **Post date:** [May 28, 2019, 9:41am UTC](https://forum.dimagi.com/t/automatic-time-calculation/1704/17 "2019-05-28T09:41:30Z")
@Ethan_Soergel, @Clayton_Sims, This is working now, i broke down the syntax in parts to evaluate. (int(substring-before(/data/timestart, ":")) - int(substring-before(/data/timeend, ":")) ) \* 60 ---
**Author:** ![JayH](https://dimagi.b-cdn.net/letter_avatar_proxy/v4/letter/j/6a8cbe/32.png) [@JayH](https://forum.dimagi.com/u/JayH)\ **Post date:** [July 10, 2019, 3:24pm UTC](https://forum.dimagi.com/t/automatic-time-calculation/1704/18 "2019-07-10T15:24:32Z")
@Ethan_Soergel, @Clayton_Sims Hi guys, Please how can i expand this function to take into account a duration less than 60mins? ---
**Author:** ![Ethan\_Soergel](https://dimagi.b-cdn.net/user_avatar/forum.dimagi.com/ethan_soergel/32/543_2.png) [@Ethan\_Soergel](https://forum.dimagi.com/u/Ethan_Soergel)\ **Post date:** [July 10, 2019, 3:58pm UTC](https://forum.dimagi.com/t/automatic-time-calculation/1704/19 "2019-07-10T15:58:46Z")
`int(substring-before(/data/timestart, “:”))` Gives the "hour" portion of the timestamp. To access the "minute" portion, use `int(substring-after(/data/timestart, “:”))` Clayton's [message](https://forum.dimagi.com/t/automatic-time-calculation/1704/11) from earlier proposed this calculation: `int(substring-before(#form/timestart, “:”)) * 60 + int(substring-after(#form/timestart, “:”))` So in full, you could make a hidden value `start_minutes` with the calculation `int(substring-before(/data/timestart, “:”)) * 60 + int(substring-after(/data/timestart, “:”))` And a hidden value `end_minutes` with the calculation `int(substring-before(/data/timeend, “:”)) * 60 + int(substring-after(/data/timeend, “:”))` Then the overall result would be `/data/end_minutes - /data/start_minutes` ---
**Author:** ![bargolus](https://dimagi.b-cdn.net/letter_avatar_proxy/v4/letter/b/57b2e6/32.png) [@bargolus](https://forum.dimagi.com/u/bargolus)\ **Post date:** [January 28, 2020, 10:47am UTC](https://forum.dimagi.com/t/automatic-time-calculation/1704/20 "2020-01-28T10:47:12Z")
I want to set up a system to check how long it takes for people to fill in sections of a single form (rather than use multiple forms). So I've used the double(now()) work-around. However, hidden values are either instantiated immediately (using the default option), or every time a question is answered (using the calculate option). Even if I use the display condition, the hidden values will be instantiated every time a question is answered as soon as the display condition is met. Is there no way to get hidden values to instantiate just once (say the first time the display condition is met) and then never again after? It might be a little bit error-prone to use if people decide to go back to previously answered questions, but given the vast majority of people just fill the form in a linear fashion from start to end, it should work fine most of the time. [Next page](https://forum.dimagi.com/t/automatic-time-calculation/1704.md?page=2)