Promote your personal finance articles on PF BuzzThe personal finance social network and news portal.
Using Simple Rules to Predict your Retirement Needs
December 6, 2007 by Pinyo.
In prior posts, I shared some financial math tricks and demonstrated a quick way to calculate your retirement needs. Now I am going to put the two together and use these rules, along with some historical inflation data, to give you a quick estimate of annual income needed for a comfy retirement.

Historical inflation data from InflationData.com
The graph above shows historical inflation rate from 1913 to 2006. Here are some quick factoids:
- From 1913 to 2006 U.S. inflation rate averaged 3.4%
- From 1996 to 2006 U.S. inflation rate averaged 2.5%, slightly lower than the longer term average
- 10 consecutive years with the highest inflation rate was between 1973-1982 at 8.8%
- 10 consecutive years with the lowest inflation rate was between 1924-1933 at -2.6% (period spanning the Great Depression)
Using the Rule of 72 and Rule of 115 and inflation rate of 3.4%, we can estimate that:
- We need 2x our current income to retire in 20 years (72 / 3.4 = 21)
- We need 3x our current income to retire in 30 years (115 / 3.4 = 34)
- We need 4x our current income to retire in 40 years (72 / 3.4, twice)
After reading Chief Family Officer’s comment, I concluded that: A better way to estimate is not to base it off your current income, but off your current estimated annual living expense. The reason is simple, some people make $50,000 a year and could live on $25,000, and some people make over $100,000 but spend more than they earn every year.
Of course, you can apply the 80% rule that said, you only require 80% of your pre-retirement income to live comfortably in your retirement, which will lower your retirement needs by a bit. I will discuss the reasoning behind the 80% rule in a future post.
More about math rules, inflation, and retirement needs:
- Use the Rule of 72 to Understand Compound Interest @ GenerationXFinance
- Retirement Income Rule of Thumb Debunked @ Consumerism Commentary
- 5 Steps to Early Retirement @ Free Money Finance
- 3 Retirement Income Variables to Consider @ Advanced Personal Finance
- A Penny Saved is Worth More Than a Penny Earned @ Cash Money Life
Carnivals:
- This post was featured in the Link Mash-up 13 hosted by TheWildInvestor.com. For more information, please visit the Business/Finance Link Mash-up.
Promote your personal finance articles on PF BuzzThe personal finance social network and news portal.
Related Posts:
Related Tags:
compounding, great depression, inflation, math, Retirement, rule, rule of 115, rule of 72, trick4 Comments
Please share your comment:
5 blogs that link to this article:
If your trackback does not show in 24 hours, please resend to this trackback URI.
- Dec 7, 2007: The Friday Gathering for 12/07/2007 | Gather Little By Little
- Dec 7, 2007: 2007 News Archive | Moolanomy
- Dec 9, 2007: Sunday Money Roundup - Patriots Go For 13 Edition. | My Two Dollars
- Dec 18, 2007: A Deeper Look at the 80% Retirement Rule | Moolanomy
- Feb 4, 2008: January 2008 Site and Net Worth Review (-7.35%) | Moolanomy













Great article! You really bring home some relevant points in an easy to understand manner. I think I’m a little far off for an accurate estimation of my needs, but this is great for a rule of them estimation.
Thanks for including my link as well.
Thanks Patrick. I guess I am beginning to find my sweet spot. Yeah, this is a very rough estimate, but it does show the impact of inflation on your wealth. Scary.
Thanks for including my post!
I like this rule “current estimated annual living expense” I think it is a lot more accurate and reflective of future retirement financial needs