I do not have a spending budget. I am conservative with money and am fortunate to not have money worries. I figure I spend about $75 per week on average
However, I do have a mental calorie budget. (We all should.)
I aim for a nominal 600, 600, 1000 calories for breakfast, lunch, dinner respectively.
If I happen to go out for breakfast to meet a coworker I will usually spend $10 for meal coffee and tip. I’ll estimate it at 800 -1000 calories so I’ll back off on lunch.
If I skip lunch I might have a glass of sweet white wine with dinner. I might add a dessert – left over chocolates that have been sitting around since the last holiday.
If I am going to be working very hard for sustained periods in cold climate I will bump up the calorie budget to about 4000 calories per day.
I do not keep notes or diary. I did it for a short while about 30 years ago and learned to estimate.
A quick step on a scale tells me if I am trending high or low and I’ll make a minor correction either way.