We use QGIS as a field application. We like to calculate with a input value and then also calculate with the result of the calculation

Example: Liters: 1000 -> Liter per container: "this has to be Liters / 3 With the result of Liter per container we also want to calculate

Did use the field calculator, but this doesnt work real time.

IS there a option to do the calculation real time?


Yes - what you're after is called a "virtual field". Open the layer properties and switch to the "fields" tab. Then, click the "field calculator" toolbar icon.

Check the "Create virtual field" checkbox, and make sure you choose an appropriate name and field type for your virtual field. Then, enter the associated expression - eg

"Liters" / 3

Click OK, and you'll have a new auto-updating virtual field which will change whenever the "Liters" attribute changes...

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  • Thank you for the answer. Only the calculation of field isnot done realtime on the screen but at the time when you save it to the table. I have a location, on this location a want to insert some information. With QT have made a input form. When a insert a value in the Liters field the calculation hasto be done on screen realtime, because the result of this is a input for another calculation. – Kaj Sep 3 '15 at 16:51

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