# Which is the best value? Kg or ltrs?

Found 26th Mar
I'm wanting to buy pet bedding which are wood based, one is weighed at 20kg wood shavings and the other is 85 ltrs of wood pulp.The 20kg is £1 cheaper but which is the better deal? I'm rubbish with maths and equasions.
If my maths is correct, and my recollection of physics, wood because it floats is less dense than water. This means that 1KG of wood will displace more than 1 litre of water. So if you use the approximation that 1kg = 1.2lt water, then your 20kg is only going to displace 24lt water.. Allowing for the air in the the wood shavings you can increase that figure to 30 litres. This makes the 85 litres pack better value, though you do have to take into account the £1 difference.
The most accurate way to compare would be to buy the 85litre pack and weigh it, doing a price per kg. At least you will only pay more a maximum of one. But I'm pretty sure my maths is correct.
mrty5 m ago

If my maths is correct, and my recollection of physics, wood because it …If my maths is correct, and my recollection of physics, wood because it floats is less dense than water. This means that 1KG of wood will displace more than 1 litre of water. So if you use the approximation that 1kg = 1.2lt water, then your 20kg is only going to displace 24lt water.. Allowing for the air in the the wood shavings you can increase that figure to 30 litres. This makes the 85 litres pack better value, though you do have to take into account the £1 difference.The most accurate way to compare would be to buy the 85litre pack and weigh it, doing a price per kg. At least you will only pay more a maximum of one. But I'm pretty sure my maths is correct.

Thank you.
Why not just ask the seller how much the 85 litres weighs?
There is no mathematical solution to your question.
I would personally go with the 20kg bag. The 85l bag could be loosely packed meaning you don't get much in it whereas 20kg should be weighed and be 20kg worth of shavings.
mrty9 h, 37 m ago

If my maths is correct, and my recollection of physics, wood because it …If my maths is correct, and my recollection of physics, wood because it floats is less dense than water. This means that 1KG of wood will displace more than 1 litre of water. So if you use the approximation that 1kg = 1.2lt water, then your 20kg is only going to displace 24lt water.. Allowing for the air in the the wood shavings you can increase that figure to 30 litres. This makes the 85 litres pack better value, though you do have to take into account the £1 difference.The most accurate way to compare would be to buy the 85litre pack and weigh it, doing a price per kg. At least you will only pay more a maximum of one. But I'm pretty sure my maths is correct.

But youre comparing two different products, shavings and pulp.
ibblackberry19 m ago

But youre comparing two different products, shavings and pulp.

Still basically wood shaped differently. I know my calculations are approximations, that is why I finished by saying the best thing to do is buy one and weigh it (easier to weigh the volume product than to calculate the volume of the weightedproduct.
mrty2 h, 7 m ago

Still basically wood shaped differently.

Not at all, when it comes to volume particle size and shape have a huge impact.

If you tip out a bag of wood shavings onto the floor then the pile is far, far less dense than a piece of wood of the same shape.

It's likely that shavings in a packet will be compressed to some extent but I wouldn't expect it to be anywhere close to the density of solid wood. If it were it would be Stirling board, not pet bedding.

It's unlikely an 85L bag of pet bedding is going to be significantly more than 20KG and may be less. It depends on how much it's compressed so it's impossible to say for sure without weighing it.
I don't know why they would weigh one as kg and the other as ltrs anyway, I'll get the store person to do the lifting and weigh the ltrs bag.
mrty20 h, 59 m ago

If my maths is correct, and my recollection of physics, wood because it …If my maths is correct, and my recollection of physics, wood because it floats is less dense than water. This means that 1KG of wood will displace more than 1 litre of water. So if you use the approximation that 1kg = 1.2lt water, then your 20kg is only going to displace 24lt water.. Allowing for the air in the the wood shavings you can increase that figure to 30 litres. This makes the 85 litres pack better value, though you do have to take into account the £1 difference.The most accurate way to compare would be to buy the 85litre pack and weigh it, doing a price per kg. At least you will only pay more a maximum of one. But I'm pretty sure my maths is correct.

If it floats its a witch, or a duck, I'm not sure.