How much topsoil?

[krasnayaplats]

I have a raised bed that is about 3 ft by 10 ft. The soil has sunk down a bit so I want to add maybe 3 or 4 inches of soil. I am unsure how much I need in litres. It seems to come in 25 l bags. I spotted a 5 for the price of 4 deal, so was thinking of getting 125l but wonder if that will be far too much? Grateful for any advice.

No, not close to enough to get you 3 or 4 inches by my reckoning - in metres, your bed is about 1.5x3m, so a total area of 4.5 sqm.

1 cubic meter is 1000 litres, so your 125l is .125 cubic metres, or enough to cover 1 sqm to a depth of 12.5cm or around 5 inches.

If you spread it over the 4.5 sqm, it will only give you a depth of 2.8cm, so just over an inch.

Unless I am getting my maths very wrong, which is entirely possible at this time of the evening!