How much to retire. Need Excel and Math gurus

[civil4life]

I am 34 years old.  After starting to read Mr. Money Mustache I have made a goal to retire by 40.  As I have been reading and evaluating my finances I wonder if I can achieve FI even earlier.

Looking at a future retirement budget, I will need about $25k annually.  I anticipate being able to max out my contributions to 45k and IRA the rest of my career.  Since I have a 457 I am able to withdraw from the account as soon as I leave this job.  I do not have to wait until I am 59.5 years old.

I absolutely need to work 2 more years to be vested in the pension.  Additionally, my retirement salary is based on an average of my top 3 years pay.  This past year I jumped from making $76k to $96k.  I need the 2 years to get the much higher average.  In retirement I would receive a percentage of the average high pay based on the years of service.  For each year of service I would get 2% of my highest pay.  So if I assumed retiring at 40, I would have 16 years of service and would receive 32% of the high average.  Worst case $96k therefore an annual income of $30k.  The only thing is I cannot draw from the pension until I would have met normal retirement.  For me that would be 60 years old.

The current balance of my 457s are $21k and  $70k.  I have $5.6k in my IRA.  My 457s are in the T. Rowe Price 2050 target fund.

I want to determine based on my current level of investment how much I need in the time between I retire until I can touch my pension and from my pension until SS.  Also for my situation when is the best time for me to start SS (62,67,70) Right now this is what SS has as my estimated benefit:

At early retirement age (62)(2045): $1,652 a month
At full retirement age (67)(2050): $2,352 a month
At age 70(2053): $2,917 a month

*I do not plan to work and contribute to SS until retirement so I am guessing these will be higher than my actual benefit.

I am horrible with present and future value stuff.  I can do it but I screw it up easily.

Assuming that I only max out my 457 and IRA until I retire.  Right now ($24k).  Also assuming the contributions are done biweekly evenly.

How much will I need to retire?  I know from the simple math it is $625k without pension and SS so worst case.  I am looking for best case.

Thank you
If you do it in Excel please share the spreadsheet, If not can you share the calculations with me.

[MDM]

For multi-year planning, with step changes in expenses or income, consider one of these Best and/or Recommended Retirement Calculators.

You could put your numbers into the "Calculations' tab of the case study spreadsheet and assume no pension or SS, but that would likely be overly conservative.  For an even simpler approach, see rows 46-67 of the 'Misc. calcs' tab in that spreadsheet.

But one of the tools in the first link, or Quicken's Lifetime Planner, etc., are probably more suited to your situation.  Whatever you do will have a very large plus/minus band, given your current age.

[aspiringnomad]

Personal Capital also has a retirement planning tool that allows for changes in income and benefits received over time. It uses Monte Carlo simulation to project the likelihood of your retirement being a success (i.e., not running out of money). And/or you could do it the Mustachian way (DIY), learn some fun and valuable excel skills, and customize the analysis and presentation to your heart's content.