How much screen wash to water is 20% to 80%

Idontlikeworking

I'm no good at maths so can someone work out how much screen wash and water I need.

I bought a 250ml bottle of screen wash that says to use 20% Volume and 80% water so how do I work out how much is 20% and 80%. The place I bought the screen wash said it will make up to 4 litres so I'm thinking there ratio is 50ml screen wash and 800ml water but is this correct.

kimwp

A couple of ways you can think about this-
20% is 1/5 and 80% is 4/5. Whatever you put in of screen wash, you need to put in four times that of water.

So, you can use a small container and fill it with screen wash once and empty it into a bigger container or your car car. Then fill up the same small container four times with water.

Or, if you have a see-through bottle, you can measure 1/5 of the height of the bottle and mark a line. Then you pour on screen wash up to the line and fill the rest of the bottle with water. (I keep a 2l bottle of screen wash in the car for top-ups)

Either method is the same result - you are using five "measures" of liquid total - one measure of screen wash and four measures of water.

Hth

elsien

20% is 1/5 or multiply by 0.2
80 % is 4/5 or multiply by 0.8

What size container are you going to be measuring/mixing it with? 

I usually use a 1L jug so that would be 200 ml of screenwash and top up to the litre mark with water. (800 ml)

Car_54

250 screen wash, 1,000 water.

Or to make a litre, 200 + 800.

don’t worry, nothing awful will happen if you get it wrong.

kimwp

NB, if you use the whole bottle of screen wash at the 20% to 80% ratio, this will only make 1.25 litres. I think "up to 4l" must mean you can do a more dilute solution.

Apodemus

20% would be 200ml made up to a total of 1 Litre (ie adding 800ml of water).  If you pour the whole bottle into your screenwash container in the car, you then add 1Litre of water, making 1.25 Litre of diluted screenwash in total. 

But don't worry if you over or under dilute it, you won't cause any harm either way. 

maman

Unless you have an old measuring jug, to keep for this sort of thing... an average size can (baked beans or tinned tomatoes) is about 400 ml. You'd need half a can of screen wash to 2 cans of water to make a litre diluted. 

Apodemus

Or simply pour the lot into the screenwash container in the car and use the empty bottle four times to add the water.

jackieblack

kimwp said:

…  I think "up to 4l" must mean you can do a more dilute solution.

Or that the person selling it has very poor maths skills 

Mildly_Miffed

Idontlikeworking said:

I'm no good at maths so can someone work out how much screen wash and water I need.

I bought a 250ml bottle of screen wash that says to use 20% Volume and 80% water so how do I work out how much is 20% and 80%. The place I bought the screen wash said it will make up to 4 litres so I'm thinking there ratio is 50ml screen wash and 800ml water but is this correct.

It's very straightforward to work out this kind of proportion.

20% concentrate to 80% water
...knock the 0 off and ignore the %.

2 bottles of concentrate to 8 bottles of water
...half that

1 bottle of concentrate to 4 bottles of water

1 x 250ml plus 4 x 250ml = 1250ml, a litre and a quarter. Nowhere near four litres, obvs.

Yes, you can mix it thinnner - but it's not going to work as effectively, and come winter it'll freeze more readily.

Your suggested 50ml to 800ml...
50:800
...knock a zero off

5:80
...double

10:160
...knock a zero off

1:16

So you'd be putting four times as much water in as they recommend.
1 x 250ml plus 16 x 250ml would be one bottle to four litres - so four and a quarter litres.
I wouldn't bother with it that thin - you might as well just use neat water.

If you really wanted their "4 litres", then you're forgetting that you already put a bottle (of screenwash) in out of the 16 total to make four litres - so you'd add 15 of water instead.

If you find the mixing proportions confusing, it might be easier just to buy ready-mix screenwash.

Or just shrug, chuck the full bottle in the empty screenwash tank, then top it up with water...

Bigwheels1111

This is getting complicated.
Just buy pre mixed next time 
Plus use deionised water to dilute the screenwash.
Stops jets getting blocked with lime scale.