[pasta]

If you need to estimate then it's best to break work up in small parts and then estimate those. Because it's very tricky to estimate huge bulks of work.

There is however a lot of work you cannot estimate. If you still need to estimate the work you sometimes can set a max. For example you estimate that a API integration will cost you 16 hours but there are a lot of uncertainties. Then you can tell the client that you bill by the hour with a max of 32 hours.