Everyone knows the more they spend now, the less they will have later. Almost all financial advice available encourages more saving. I don\u2019t disagree, but there should be a balance.\r\nDue to diminishing marginal returns, most people can maximize the usefulness of their money if they are able to generally smooth consumption over their lifetimes. It is ok to spend a bit more now than later, but don\u2019t assume you won\u2019t want the money just as much when you are older. You will.\r\nTo make intelligent tradeoffs such as one nice vacation now or two later, it is helpful to understand and quantify how much saving now actually increases future consumption. Let\u2019s try.\r\nReal Growth Rates\r\nMost financial advice about saving tells you something like, \u201cIf you invest $X, in Y years you will have $Z\u201d, where Z is usually a lot of money.\r\n\r\nThe point is correct, but there are two problems. First, it ignores taxes and inflation. This makes a big difference. Second, we know the assumptions will be wrong, but we don\u2019t know how wrong. Will Z be off by 20% or 80%?\r\n\r\nLet\u2019s try to think about it correctly.\r\n\r\nThe following tables show how much money $1 saved will be worth, after taxes and inflation, for given time periods. It uses an 85% stock and 15% bond portfolio, and assumes 8% returns for stocks, 4.5% for bonds, and 3% inflation.\r\n\r\nFor those who are still working, the tables below also give an estimate for how much can be withdrawn each year in retirement as a result of the extra dollar saved. For this, they use a fairly standard 5% withdrawal rate. This is also inflation adjusted.\r\n\r\nObviously, real world results will be different, but this gives us a good general framework to better understand saving. \u201cReal Value\u201d means inflation adjusted back into today\u2019s dollars. The 5% annual withdrawal is also inflation adjusted into today\u2019s dollars.\r\n\r\n\r\n\r\nFor example, $1 saved now and held 20 years results in about $2 of extra savings after inflation, and an extra $0.10 per year in retirement spending.\r\n\r\nOr, using the table on the right, saving $1 every year for 20 years should result in about $29 of extra savings after inflation, and an extra $1.43 per year in available retirement spending.\r\n\r\nIf we think about this in percentage terms, saving $10 percent of income every year for 20 years may lead to an extra 14.3% of current income to spend in retirement. So it turns out saving 10% every year is unlikely to lead to a dream retirement, though you will also have Social Security and possibly other income to help.\r\n\r\nAgain, these are only estimates. But the tables provide a good framework for understanding what to expect when devising a savings plan.\r\nTarget the Median\r\nThe numbers above represent the median expected value. In real life, results will be different. Assuming you own stocks, which you should, you will probably end up with a lot more or a lot less.\r\n\r\nAs a very, very rough estimate, with an 85% stock portfolio, after twenty years you should expect one standard deviation of the final value to equal about half of the total expected value.\r\n\r\nThis means about a third of the time your estimate will be off by more than 50%. If you expect to have $1 million, there is a 32% chance you will have less than $500K or more than $1.5 million. There is a 68% chance you will have between $500K and $1.5 million. Dispersion gets even bigger if the time horizon is longer.\r\n\r\nBecause most people are more concerned with the bad scenario, in very rough terms, assume about a 15% chance of having less than half of the expected amount.\r\n\r\nStill, for planning purposes, it is generally best to target the median with the expectation that the final value will likely come in somewhere between 50% and 150% of what you expect. Luckily, with saving, you can adjust as you go along.\r\nConclusions\r\nA few of you, may be thinking, \u201cHey, this all sounds great\u201d, but most of you are thinking, \u201cThat\u2019s it?\u201d and \u201cThis stinks\u201d.\r\n\r\nWell, yes. Investing helps, but most likely we will have to save most of the money we ultimately spend. We may get another period like the 1980\u2019s \u2013 1990\u2019s with huge returns, but we can\u2019t count on it.\r\n\r\nBefore you give up on saving, consider that in the real world the money you save will be used in one of two scenarios.\r\n\r\n \tIf investment results turn out worse than expectations, you may need this extra money to maintain your basic living expenditures, in which case you will be really glad you have it.\r\n \tIf investment results are better than expected, the extra amount will grow to be larger than projected, and you can spend this surplus more aggressively.\r\n\r\nPlease don\u2019t use this information to decide that saving is not that important. Along with making a lot of money, saving is the best way to ensure financial success.\r\n\r\nIt is possible to save too much, but most people end up wishing they had saved more, not less.\r\n\r\nIf you think you won\u2019t care as much if you don\u2019t have money when you are older, the experience of millions of others before you says you are wrong (unless you die before you get there).