When I started the topic of building a house and made the first calculations in the form of a liquidity plan, I roughly estimated the topic of food + hygiene for 2 people at €250, since the weekly shopping was always under €40 and thus around €160/month. Occasionally, there was also the canteen for lunch, which brought me to my €250. I estimated the topic of "miscellaneous" roughly at €200 in the same way. The total was thus €450. In hindsight, that could never have been correct.
Now that a child has been added, prices in the store and especially in the canteen have risen, and something is always needed from the hardware store for the house + garden, I currently calculate €850 for food/hygiene and miscellaneous. Nevertheless, the account balance is a little lower every month than expected. Somewhere in the cash area, more must be spent than I expect, because everything that goes through the account I check randomly with my liquidity planning. The almost €450 additional requirement is not dramatic for us, as we have allowed ourselves enough leeway and appropriate salary adjustments have taken place during that time, but if you are already financing tightly, such an additional requirement can be disastrous.