I see a lot of questions about what percentage to contribute to a 401k. Here's the framework I used.

Step 1 is non-negotiable: contribute at least enough to get the full employer match. This is an instant 50-100% return on your money depending on the match structure. There is no better guaranteed return anywhere.

Step 2: evaluate whether you should max it ($23,000 in 2024) or split between 401k and Roth IRA. This depends on your marginal tax rate now vs expected tax rate in retirement. If you're in a high bracket now, more traditional 401k. If in a low bracket now, more Roth.

Step 3: if you can afford to contribute more than the match but not the full max, increase by 1% of salary every 6 months. You'll barely feel it due to wage growth, and after a few years you'll be at 15-20% without a single painful cut.