If you’ve ever tried to stick to a budget that splits your money into 10 different categories—groceries, gas, dining, personal care, entertainment, subscriptions, and so on—you probably found out the hard way: it’s a lot to track. For many people, this complexity turns budgeting into something they start with enthusiasm but abandon quickly.
That’s where the “one-number” method comes in. Instead of juggling multiple spending limits, this approach simplifies everything down to one question: How much can I spend this week—total? No breakdowns. No spreadsheets. Just a single number to guide your everyday spending decisions.
It’s a method that works because it’s easy to remember, flexible to adjust, and based on the actual money you have—not idealized budgets you hope to follow.
How the One-Number Method Works
At its core, the one-number method is about subtracting your fixed obligations—like bills and savings—from your income, and then dividing what’s left by the number of weeks in the month. That weekly number becomes your all-in guide for flexible spending. Groceries, takeout, errands, coffee, random Amazon buys—they all come from that number.
The reason this approach is so helpful is because it eliminates the need to track categories individually. You’re still managing your money—you’re just doing it in a way that’s more intuitive and realistic for how most of us actually spend.
Step One: Know What You Have to Spend
To get started, look at your monthly take-home income (after taxes). Then subtract the things you’re committed to paying each month, including:
Rent or mortgage
Utilities
Insurance
Minimum loan payments
Subscriptions
Your target savings amount
What’s left is your total for flexible spending—this is the money you control day to day. Divide that leftover amount by the number of weeks in your month (usually four or five), and that’s your “one number.”
For example:
Monthly income: $3,000
Fixed bills and savings: $2,200
Leftover flexible spending: $800
Divided by 4 weeks = $200 per week to spend
That $200 is your weekly budget. You don’t need to split it up into 15 different buckets. Just stay within that number, and you’ll stay on track.
Why Weekly Works Better Than Monthly
Most people find that a monthly spending limit is too abstract. It’s hard to remember how much you’ve spent, and even harder to course-correct if you blow half your budget in the first 10 days.
Weekly limits, on the other hand, are easier to manage because they reset regularly. If you overspend a little one week, you don’t have to wait a month to try again. There’s a new window every seven days to make smarter choices—and that’s motivating.
It also matches more closely with how people actually shop and live. You might grocery shop once a week, grab takeout once or twice, or run errands on the weekend. A weekly number gives you permission and structure without turning budgeting into a full-time job.
Use One Account (or Card) to Track It All
To make the one-number method work even better, try using a separate checking account or debit card for your weekly spending. Move only your one-number amount into that account each week and use it for all your day-to-day purchases.
This creates a natural boundary. When the money’s gone, you know you’ve hit your limit—without needing to check your main account or worry about overspending bill money.
Many people find this “digital envelope” approach helpful because it adds clarity without requiring detailed expense tracking. You still get the benefit of being intentional, but with way less friction.
How to Adjust Your One Number When Life Happens
Life is unpredictable, and one of the strengths of the one-number method is how easy it is to adjust. If your income changes or you have a heavier month (like during the holidays or a busy season for kids), simply re-calculate your number based on that month’s reality.
It’s also helpful to set aside a little buffer in your overall budget for things that fall outside your normal spending—car repairs, gifts, or unexpected fees. That way, your weekly spending number doesn’t take the hit when surprises pop up.
If you want to get even more flexible, you can “roll over” part of your weekly spending if you don’t use it. For example, if your number is $200 but you only spent $150 this week, you can start next week with $250. Just be careful not to treat rollovers as a reason to binge—they’re better used for bigger purchases you’ve planned for.
Things to Watch For With This Method
The one-number method is simple, but not foolproof. Some people may struggle to stay within their limit if they’re used to using credit cards or have inconsistent income. If that’s the case, you might need to pair this method with a couple of guardrails.
A few tips to stay on track:
Don’t forget to update your fixed expenses if anything changes
Recalculate your number monthly—not just once and forget it
Check your account a few times a week to stay aware of where you stand
Consider automating your weekly transfers so the money shows up without effort
Use a simple note app or spreadsheet to jot down your weekly spending if needed
Ultimately, this method works best when you stay a little bit involved—not micromanaging, but not fully hands-off either.
Where It Leads
Budgeting doesn’t have to mean tracking every latte or feeling guilty every time you order takeout. The one-number method keeps things simple. You know your bills are covered. You’re putting money toward your goals. And you have one clear, flexible number that keeps your spending in check without all the stress.
If traditional budgeting hasn’t worked for you—or you’re just tired of trying to manage ten categories at once—this might be the approach that sticks. Give it a few weeks, see how it feels, and adjust as needed. Sometimes the best money strategy is the simplest one.
