Budget Planner
A monthly budget from a pasted list, with annual costs spread into a monthly line and the needs and wants split measured against the 50/30/20 rule.
Take-home a month £3,100.00
Monthly costs £2,403.50 across 11 lines
Annual and irregular costs £2,400.00 a year
as a monthly line £200.00, which is the part most budgets leave out
Total spending £2,603.50
Left over £496.50
as a share of take-home 16%
a year £5,958.00
reading the month balances with something left, which is the only version of a budget that survives contact with a bad month
Where it goes
housing £1,524.50, 49.2% of take-home across 4 lines
food £600.00, 19.4% of take-home across 2 lines
saving £100.00, 3.2% of take-home across 1 line
transport £95.00, 3.1% of take-home across 1 line
fun £62.00, 2% of take-home across 2 lines
bills £22.00, 0.7% of take-home across 1 line
The largest lines
Rent £1,200.00, 38.7% of take-home
Groceries £420.00, 13.5% of take-home
Eating out £180.00, 5.8% of take-home
Council tax £165.00, 5.3% of take-home
Energy £120.00, 3.9% of take-home
Against the 50/30/20 rule
needs £2,241.50, 72.3% against 50%
wants £162.00, 5.2% against 30%
saving £496.50, 16% against 20%
note the sinking fund is counted as spending here, not as saving, because it is already spoken for
reading needs are above half of take-home, which the rule reads as a problem and is often simply what rent costs where you live. The rule is a heuristic from a 2005 book rather than a law.
If the income stopped
savings £6,800.00
months of this spending 2.6
on needs alone 2.8 months
What a change would be worth
5% less spending £130.18 a month, £1,562.10 a year
10% less spending £260.35 a month, £3,124.20 a year
5% more income £155.00 a month before any tax on it
The annual costs are £200.00 a month. That is the line that breaks
budgets: insurance, maintenance, dentistry and birthdays are real and
they do not arrive monthly, so a budget built from monthly bills works
until one of them lands.
There is £496.50 left, which is £5,958.00 a year. A budget that balances
exactly is a budget with no room for a bad month, so the margin is the
point rather than a rounding error.
The largest lines are where the money is. Cutting a third off housing,
transport or food changes more than cutting everything else to zero,
which is why a budget that starts with small luxuries usually fails: the
effort is inversely proportional to the effect.
Needs and wants are decided by the groups you tagged, because the line
between them is a judgement about your life rather than an accounting
fact. A car, a phone contract and childcare all sit on different sides
of it for different people.
50/30/20 comes from Warren and Tyagi's All Your Worth in 2005, and it
was a rule of thumb then. Housing costs in most cities have moved a long
way since, so missing the needs target is frequently a fact about rent
rather than a fact about discipline.
A budget is a forecast, and the useful version is written down and
compared against what happened. The gap between the two is the only part
that teaches anything, and it is the part nearly everybody skips.
Irregular income makes this harder and not impossible. Budget on the
lowest month rather than the average, and treat the difference in a good
month as the sinking fund rather than as income.
Output is valid and updates as you type.
Fix the highlighted fields to update the output.
Two things break most budgets, and neither is discipline.
The first is irregular costs. Insurance, car maintenance, dentistry, birthdays and a holiday are real and annual, and a budget built from monthly bills is short by a twelfth of them every month. It works for four months, then a bill arrives and the whole thing gets written off as unrealistic. Dividing the annual total by twelve and treating it as a monthly line is the entire fix, and on the example it is £200.
The second is the tidy percentage rule. 50/30/20 comes from Warren and Tyagi’s All Your Worth in 2005, and it was a rule of thumb then. In an expensive city rent alone can pass half of take-home, which makes the rule a description of a problem rather than a target. Needs on the example are 72.3 percent, and that is mostly a fact about rent.
How to use
- Put in take-home pay for the month.
- Paste the monthly costs, one a line, as a label and an amount. A group after a pipe is used for the needs and wants split.
- Total your annual and irregular costs for the year and put that in. It is the line that decides whether the budget survives.
Example
£3,100 take-home, eleven monthly lines, £2,400 of annual costs and £6,800 in savings:
Monthly costs £2,403.50 across 11 lines
Annual and irregular costs £2,400.00 a year
as a monthly line £200.00, which is the part most budgets leave out
Total spending £2,603.50
Left over £496.50
as a share of take-home 16%
a year £5,958.00
Where it goes
housing £1,524.50, 49.2% of take-home across 4 lines
food £600.00, 19.4% of take-home across 2 lines
transport £95.00, 3.1% of take-home across 1 line
The largest lines
Rent £1,200.00, 38.7% of take-home
Groceries £420.00, 13.5% of take-home
Against the 50/30/20 rule
needs £2,241.50, 72.3% against 50%
wants £162.00, 5.2% against 30%
saving £496.50, 16% against 20%
note the sinking fund is counted as spending here, not as saving, because it is already spoken for
If the income stopped
months of this spending 2.6
on needs alone 2.8 monthsMissing the needs target by 22 points while still saving 16 percent of take-home is a recognisable situation, and no amount of cutting subscriptions changes it.
Pitfalls
A budget without annual costs is wrong by design. They are the reason budgets fail in month five. Total them once a year and carry a twelfth every month.
The sinking fund is spending, not saving. The money is already allocated. Counting it as savings makes the savings rate look better and the next dentist appointment a surprise.
Cut the largest lines or do not bother. Housing, transport and food are usually the top three. Cutting a third from any of them beats cutting everything else to zero, which is why a budget that starts with small luxuries fails.
Needs and wants is a judgement. A car, a phone contract and childcare sit on different sides of the line for different people, which is why the groups are yours to tag rather than ours to decide.
Missing 50/30/20 is often a fact about rent. Housing costs in most cities have moved a long way since 2005. Read the miss as information about the market rather than a verdict on your choices.
A budget that balances exactly has no room. The surplus is the point. A month with no margin is a month where one repair becomes debt.
Irregular income makes this harder, not impossible. Budget on the lowest month, and treat a good month’s excess as the sinking fund rather than as income.
Compatibility
Arithmetic in the browser: nothing is uploaded and nothing is stored, which matters when the list is pasted from a bank export.
The list is parsed rather than entered field by field, so a spreadsheet paste works. The amount is the last number on a line, which means a label can contain digits (“Zone 1-3 travel card 95”), and a line with no number is treated as a heading rather than counted as a zero, since a silent zero would change every total.
The needs and wants split is driven entirely by the group names you tag as needs. The test suite asserts that changing the tagged list moves money between needs and wants and leaves the totals alone, which is the behaviour that makes the split honest rather than editorial.
Savings give a runway in months, once against total spending and once against needs plus the sinking fund, since those are the two versions of the question worth asking.