Monthly Home Budget Planner

Most people who say they have a budget have a list of bills. What the list rarely shows is the one number that decides whether the month works: how much of your take-home pay each line eats. The Monthly Home Budget Planner puts that share beside every amount you type and sorts each line into one of three buckets, Needs, Wants or Savings.

Then it holds the totals up against the 50/30/20 rule. Half of income to needs, 30% to wants, a fifth to savings and extra debt payoff. Nothing you enter leaves the page, so real salary figures are fine to use.

The page opens on a US household earning 4800 a month with eleven lines, starting with Rent at 1450. It lands where a lot of real budgets land: needs at $2,700 (56.3%), wants at $700 (14.6%), savings at $880 (18.3%), and $520 that nobody has given a job. Load Sample then cycles through a euro, a pound and a rupee budget, and the pound one overspends by £125.

Getting Your Month onto the Page

1. Type your monthly take-home income, after tax, and pick a Currency. Ten are listed, and JPY formats without decimals.
2. Add one line per expense. Give it a name, an amount and a bucket; the bucket menu is colour-coded so a misfiled line stands out.
3. Press Enter in the last amount field to add a new line in the same bucket, with the cursor already in its name box. You can type a whole month without touching the mouse.
4. Read the comparison table, then the blue note under it. It tells you the smallest move that fixes the plan.
5. Copy Summary exports the bucket totals and every line as plain text for a notes app or a message to a partner.

How the Math Splits 50/30/20

Each bucket total is divided by income, not by total spending. That choice matters. Against spending, the sample's needs would look like 63%; against income they are 56.3%, because the $520 left over still belongs to you. Targets are income × 0.5, 0.3 and 0.2, so $2,400, $1,440 and $960 here.

• Needs come out $300 over their $2,400 target.
• Wants sit $740 under, which is headroom rather than a problem.
• Savings are $80 short of 20%.

So the note reads “Moving $80 of the $520 left over into savings reaches the 20% target.” When planned spending passes income, the bar rescales to spending and a red line marks where your pay runs out. The second card switches from Left over to Shortfall.

What This Rounds and What It Assumes

Totals are rounded to the cent after summing, which keeps 0.1 + 0.2 float noise off the screen. Shares show one decimal. Amounts may contain commas or spaces, so 1,450 reads as 1450, and a blank amount is skipped rather than counted as zero. A letter or a minus sign stops the calculation with a message naming the line, such as “Line 3 ("Groceries"): amounts cannot be negative.” An income of zero or below returns “Income must be a number greater than 0.”

A plan holds up to 40 lines. The 50/30/20 split is a rule of thumb from Elizabeth Warren's All Your Worth, not a law. In a high-rent city, needs above 50% can be unavoidable, and the useful reading is how far over you are, not whether.