Billing by the day is not the best for everyone: billing by the hour can give you the flexibility to work incomplete days or switch between clients during the day.

I billed by the hour and I regretted it. The admin overhead of generating an invoice for 60m of work is not worth it.

I bill by complete days now, so I don't take on work that is less than a day.

If I work half a day for a client, the next day I will work half a day in the rest of that job.

This still gives me the flexibility to not get bored in a single day.

> If I work half a day for a client, the next day I will work half a day in the rest of that job.

This sounds like a day here means "about 8 hours" as opposed to "the work performed during a given calendar day". Makes sense.

I think maybe the premise is having minimums per day so you can’t be called on a weekend and only bill half an hour for it

It would suck if I was called in on a weekend (without having agreed to be on call). It would suck even more if I was called in for a whole day just because I'd demanded that to be my minimum. Instead, weekend hours could be priced 16 times higher. There could be a quantity discount so that a full day would be somewhat less expensive.

>It would suck even more if I was called in for a whole day just because I'd demanded that to be my minimum

This isn't really how it works though. If you find "getting called in" (what does this mean?) to be terrible, you should be charging more for that service. You should be in control.

The whole point is to generate enough surplus value that your client signs the cheque, no questions asked, and is happy to do it. You shouldn't squabbling over hours.

I don’t think it means you work a full day, but that you bill a minimum of a full day for any weekend work.

A while back I worked at a consultancy that typically billed using a 15-minute granularity during standard office hours, reasonably rounded up/down. Unless otherwise contracted, outside of office hours the granularity increased to 1 hour rounded up. A 5 minute fix would be billed as an hour, a 65 minute fix as 2 hours, etc. It was also only undertaken for emergencies; general work requests would be done the next business day.

Generally all contracts were budgeted some number of hours per billing cycle per service. N full-time engineers would be converted to an equivalent amount of hours for the budget.

The result was that overtime was used judiciously and clients were rarely insisted on pushing big changes near the end of a day or on Fridays.

I never had the ability to bill by the day, but if I head back to contracting will try it. By the time I learned about it, I didn't have new clients coming in the door to experiment with. And existing clients and I were okay with billing by the hour.

I think that it is unabashedly a pro, because whenever you are adding value to the business and can defend it in an invoice, you're able to get value for it. Unlike when you are a salaried employee and the extra hours don't get you anything material (maybe noticed and provided with a raise. maybe).