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How can one estimate the resource usage breakdown of a project at initial proposal time?
For example in fixed price project, say a ten-member team project with project duration 12 months
Are there any standards (in terms of percentage of resources) available to estimate the team?
A twelve-month project is essential one person-year per resource. There are a number of ways to calculate a person-year, but in the US the typical baseline figure is 2,000 hours annually.
(40 hrs/week * 52 weeks) - 10 days paid time off
Calculations can vary. Some companies subtract holidays, sick days, vacation days, and paid time time (PTO) as separate line items from the annual total, while other companies use a different starting figure than 2,080 working hours per year. In other words, your mileage may vary.
Assuming you use the baseline figure of 2,000 man-hours per resource per year, you will have:
2,000 man-hours per resource * 11 people = 22,000 man-hours per year
One assumes they won't all have the same hourly rate or salary, but you could certainly average it out for a quick-and-dirty estimate, or provide a resource-by-resource breakdown if you need a more accurate figure. For example, if your 11-person team has an average salary of $80,000 per year, then you might estimate $880,000.00 for your annual labor budget, or round it up to $1M as a modest fudge factor.
I'm unaware of any way to get a finer-grained estimate of per-resource utilization unless you front-load the work of defining your work breakdown structure (WBS) and assigning resources to each work package. In other words, if you estimate you will only need 3 developers for Package A, but six developers for Package B, you can certainly create some pretty charts with that sort of information.
In my personal experience, though, it's all hogwash. Parkinson's Law is often generalized to:
The demand upon a resource tends to expand to match the supply of the resource.
Meaning that if you have 11 people assigned to a project, it will take 11 people working full time to complete the project. Charts and plans to the contrary, you should pragmatically assume full resource utilization and around 60-80% productivity. Your mileage may vary, I suppose, but I wouldn't risk the success of a fixed-price contract on the assumption that your best-case estimates are the likeliest outcome.
8 + 3 = 11. How are you getting "ten-member team" from that?