In addition to learning what percentage you should be saving, serious consideration should be given to the asset allocation in your 401k. You have a very long time horizon, which suggests that at least 80% of your investment assets should be in equities, both domestic and international. The remainder could be spread among alternatives, such as real estate, commodities, currencies, and short-term fixed income securities. This, of course, will depend upon the options available to you through your 401k plan.