Employers - how do you calculate terms? And what do you do if you can't?

Question

Career in IT

It's about the web and mobile apps.
Probably the most difficult thing is not the programming itself, and the quality of the code is not as important as the timing in this industry.
Let's say a client came to you, explained what he needed, then you spent time (1-4 days) and made up a TOR. Well, then what? What do you tell him about the timing? After all, you yourself do not know for sure, and the programmer will not be able to name specifically and accurately.
For example, let's take some CRM system tailored for business tasks as a Klint project. How do you calculate the time? And what if the programmer does not have time in the time that you set him? What's next?
I would like to hear from you detailed answers based on personal experience.

Answer 1

1. We ask employees about the time they will spend. The more experience a person has, and the more understandable those in front of him. assignment, the more accurate the estimate will be.
2. Next, we estimate which tasks can be performed in parallel and subtract these hours from the total.
3. We estimate when the employees will be free (usually when a new order comes in, a couple of old ones are still in work). Add these hours to the deadline.
4. We throw on top 20-30% of the time, for unforeseen circumstances.
5. We indicate in the contract the penalty for the day of delay.
Everything, somehow better protected from non-compliance with the deadlines will not work. Unless they check their people very carefully and weed out in advance those who constantly do not meet the deadlines.

Answer 2

In my opinion, you should not bother with calculations at all, since this is a waste of time - there will be no accurate forecast. The forecast should be made "by eye", based on the experience of working with a particular team.
The programmer estimates, he knows nothing. His forecast is usually +/- 20% Moreover, he can be an optimist, or he can increase the time frame. Or maybe get sick, or maybe something is not taken into account.
It is reasonable to increase the deadlines, since doing it "early" is good, but delaying the release is irritating

Answer 3

Well, then, based on experience, we make an assessment of performance.
We know, and the programmer quite knows how much time it will take.
Well, it depends on the contract, what is written in it and then on.

Answer 4

We estimate by eye, multiply by 10. We send it to the customer, we get indignant exclamations. We subtract 10%. The customer is satisfied. PROFIT (C) Someone