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You've decided to dollar cost average. Good. Now the next question: should you invest every week, every two weeks, or once a month? People spend way too much time on this. Here's the short answer: it barely matters. But let's look at the numbers so you can stop worrying about it.
Let's compare two investors, both putting $6,000/year into the S&P 500 at a 10% average annual return:
After 20 years with identical annual contributions:
The difference? About $1,700 over 20 years. That's less than 0.5% of the total portfolio. On a $6,000/year contribution, the frequency simply doesn't move the needle much.
Why does weekly edge out monthly at all? Because your money enters the market slightly sooner on average. Each week, a small amount starts compounding a few days earlier than it would if you waited until month's end.
Compare weekly vs monthly DCA with your exact numbers — free, no signup
Open the Free DCA Calculator →Some people take this to the extreme: invest a tiny amount every single trading day. The math says it's marginally better than weekly. In practice, the difference is so small it rounds to zero.
Daily DCA investing $6,000/year means about $23.81 per trading day (252 trading days/year). After 20 years at 10%, you'd have roughly $379,900. That's about $200 more than weekly and $1,900 more than monthly.
Not worth optimizing for. Especially when you factor in the extra tax paperwork. In a taxable account, daily investing means 252 tax lots per year per fund. When you sell, tracking cost basis becomes a headache. In a Roth IRA or 401(k), taxes aren't an issue, but the practical benefit is still close to zero.
Since the math difference is trivial, pick based on what's practical:
Choose monthly if:
Choose biweekly if:
Choose weekly if:
Frequency doesn't matter much. Consistency does. Someone who invests $500/month every single month for 20 years will crush someone who invests $125/week for 8 months, takes a break, starts again, stops again.
The biggest returns destroyer isn't picking the wrong frequency. It's stopping. People stop when the market drops. They stop when an unexpected expense hits. They stop when they get bored.
Pick the frequency that you'll actually maintain for years. That's the optimal frequency.
The best DCA schedule matches your income. Here's why: if you invest the same day you get paid, the money goes straight from your bank to your brokerage before you have a chance to spend it. It's the financial equivalent of "pay yourself first."
Set it up once with auto-invest and never think about it again. Use our budget calculator to figure out exactly how much you can invest per paycheck after covering your expenses.
Model any DCA frequency — weekly, biweekly, or monthly — and compare results
Try the DCA Calculator Now →Is it better to DCA weekly or monthly?
The difference is tiny, typically less than 0.1% per year. Weekly investing gets your money into the market slightly sooner on average, but the practical impact over 10-30 years is negligible. Choose the frequency that matches your paycheck and is easiest to automate.
Should I DCA daily?
Daily DCA offers almost zero advantage over weekly. The extra frequency doesn't meaningfully improve your average cost. It also creates more transactions, which can be a headache at tax time in taxable accounts. Weekly or biweekly is the sweet spot for most people.
When is the best day of the month to invest?
There's no consistently best day. Studies have looked at every day of the month over decades, and the differences are statistically insignificant. The best day to invest is the day you actually do it. Pick the day after payday and automate it.