Smart calculation with parameters in your posts

A post is the reusable build-up of a quotation line. With parameters you make that post smart: you ask the question once ("which colour?", "how many days?", "is the site easy to reach?") and the calculation adapts automatically. In this article we build a "Painting work" post step by step, with four kinds of parameters.

Our example contains these cost lines:

1. A choice parameter: which colour of paint?

The customer chooses blue or red — but only one of the two paint lines may count. This is how you handle that:

1. Open the parameters section in the post and create a new parameter with a unique name, e.g. kleurverf.
2. In the Description field, put the question: which colour is used?
3. Switch on "Show details". A "Possible values" column appears.
4. Enter the values between double quotation marks: "blauw" and "rood", each one followed by Enter.

The parameter now exists, but it does not influence the calculation yet. To do that we link a condition to the quantity of the paint lines. The formula

kleurverf == "blauw" ? 1 : 0

gives 1 (count it) if blue is chosen, and 0 (do not count it) if red is chosen.

Then paste the formula between brackets in the Quantity field of the blue paint line, after the existing quantity. If it says 1/100 (1 litre per 100 m²), for example, that becomes:

1/100 * (kleurverf == "blauw" ? 1 : 0)

Repeat this for the red line with "rood".

If you now choose a colour, Robaws only counts the correct paint line — the other one is set to 0.

2. A numerical parameter: how many days of aerial work platform?

For a number you do not need "Possible values": create a parameter aantaldagen and simply put the number (or a calculation formula) in the Formula column. Then paste aantaldagen in the Quantity field of the "Aerial work platform" line — the value is taken over immediately.

Do you also want the choice of whether an aerial work platform is needed? Then, just as with the colour, create a choice parameter hoogtewerker with the values "ja"/"nee" and multiply the quantity by (hoogtewerker == "ja" ? 1 : 0).

3. Predefined parameters: distance and quantity

Two parameters are always available, without you having to create them yourself:

• DISTANCE_KM — the number of kilometres that is calculated automatically on the quotation. Paste this in the quantity of your "Kilometercompensation" line and the travel cost calculates itself.
• Q — the quantity of the line itself, useful in formulas that work with the quantity entered.

4. An experience parameter: calculating what you used to forget

This is where it really gets interesting. A site is sensitive to variables that quietly eat into your margin: how easy the site is to reach, one slow lift for a whole building, limited parking, and so on. Usually you only know that afterwards: "we lost a lot of time there."

Pour that experience into a parameter. In your post, create a choice parameter vlottetoegang with the question is there easy access to the floor? and the values "ja"/"nee". Multiply the quantity of your "Working hours" line by a surcharge factor:

8 * (1 + (vlottetoegang == "nee" ? 0,15 : 0))

With "nee", your post automatically calculates 15% extra hours. Every following quotation asks the question again — the knowledge sits in the system, no longer in one person's head. Why that is so valuable is explained in What is a calculated quotation?.

5. Parameters as text on your quotation

You can show the chosen values on the quotation pdf automatically. In the Extended description of your post, put a reference with ${parameternaam}:

• Entry in the post: Kleur: ${kleurverf}
• Display on the pdf: Kleur: blauw

You can even make whole sentences depend on a choice. Create a parameter teksthoogtewerker with this formula:

hoogtewerker == "ja" ? "Er zal een hoogtewerker door ons voorzien worden voor " + aantaldagen + " dagen." : "Er wordt een hoogtewerker voorzien door de klant."

Refer to it with ${teksthoogtewerker} in the extended description. If the user chooses "ja", the pdf shows: Er zal een hoogtewerker door ons voorzien worden voor 5 dagen. With "nee": Er wordt een hoogtewerker voorzien door de klant.

Ground rules for formulas

The usual mathematical functions are available (including min, max, abs, ceil, floor, round, sqrt). In a quotation parameter (the parameters tab of the quotation, so across all lines) you can also use SUM(...) to add a parameter up across all lines.

Updated on: 04/09/2026