We've had a lot of discussions here about if it's better to take SS early or wait. I put a speadsheet together for working it out, and I'm quite surprised how the numbers are coming out. Would someone who understands finance and spreadsheets double check me?

Here's the assumptions I started with:
Used COLA of 2%
FRA is 66, at which time benefits would be 25,000.
At 64 benefits would be 21,500 (25000 x .86). Using the 2% COLA by age 90 I show total benefits to be 759,903.
Waiting until age 70 benefits would be 33,000 (25000 x 1.32). I then also applied the 2% COLA for the 6 years so that at age 70 benefits would be 37,163. Continuing using the 2% COLA by age 90 cumulative benefits would be 958,195, or 198,292 higher benefits than starting at age 64.
That is pretty much the number I think we would all expect.

Then I calculated the difference of if TP waits until age 70, but take out of retirement savings the amount he would have received in SS starting at age 64. For example, at age 64 he takes 21,500 from retirement account, at age 65 he takes out 21,930 (21500 x 1.02), and continues this for the 6 years until he starts taking benefits at age 70. For the retirement account I used a rate of return of 6%. I'm coming up with by age 90 he will have 534,213 more in retirement account if he starts SS at 64 and does not take the corresponding amount from retirement accounts. I have to take the rate of return down to 1.65% to get it to be the same as the "extra" SS benefits received by waiting to age 70 instead of 64.

I didn't expect the difference to be this large, so would appreciate if someone checks my math....

I realize there are other factors, such as if TP continues to work or not past 64, taxes, etc. Can we not bring all that into account right now and just focus on if the numbers are correct?