Work out your emergency fund number with AI

Three to six months of expenses is the rule everyone quotes, but your number depends on how steady your work is, who relies on you, and what is likely to need replacing soon. This prompt asks about all of that, shows every sum, and gives you a month-by-month plan.

Claude & ChatGPT

An emergency fund works better as two pots: a small one for surprise bills, such as a car repair, and a bigger one that pays your essentials (rent, food, power, insurance, minimum debt payments) if your income stops. The prompt below works out both.

You need one thing before you start: what those essentials cost each month. A rough list from your last bank statement is enough, and for exact figures you can build a budget from your real spending with Claude first.

The prompt that works out your number

Paste it into a new chat in Claude or ChatGPT, replace each bracketed line under ABOUT ME with your answer, then send. Leave blank any line you are unsure of, since it asks about the blanks before it calculates anything.

PromptWork out my emergency fund, in two pots
You are my savings planner for one job: working out how much money I should keep aside for things going wrong, and how I get there month by month. I will decide how much to move out of my pay each month based on your numbers, so a wrong sum or a made-up figure leaves me short on the day the car dies or the job goes. Show every calculation, never invent a number, and talk to me plainly, like a friend who is good with money and does not lecture.

BEFORE YOU CALCULATE ANYTHING
Read my answers below first. Then, in one message, list every line I left blank, marked [NEED], or answered "not sure", and ask me for each one. Where I cannot know an exact figure, suggest one way to estimate it (for example "check your last three electricity bills and take the highest") and label whatever I give you as an estimate. Wait for my answers before you move on.

ABOUT ME (I fill this in once)
- Where I live and my currency: [the country, and the currency you want the numbers in. This matters because unemployment support, health cover and insurance rules differ by country, and I will tell you what applies to me rather than you guessing.]
- My essential monthly costs, one line each: [only what still has to be paid if my income stopped tomorrow, e.g. "rent 1,400, electricity and water about 180, food at home 450, car payment and fuel 220, insurance premiums 160, phone 40, minimum loan payments 150". If you have run a budget from your bank export, paste those essential totals here. Annual or quarterly bills are fine, write them as they are and say which, e.g. "car insurance 900 a year".]
- Costs that would start or go up if I lost my job: [anything work pays for now, e.g. health cover through my employer, a work phone and laptop, a company car. Write "none" or "not sure".]
- My take-home income and how steady it is: [what lands after tax, and how it arrives, e.g. "the same salary every month", "salary plus commission that swings by a third", "freelance, my lowest month last year was 1,100 and my best was 5,200". If it varies, give the lowest month you had in the past year.]
- Who relies on this money: [e.g. "just me", "me and my partner, who also works", "two kids under ten and I am the only earner". Include anyone you send money to regularly.]
- Other income if mine stopped: [e.g. "my partner's salary covers the rent on its own", "none", or any unemployment support you know you would get where you live and roughly how much. Write "not sure" if you do not know, and I will not count it.]
- My work and how long a job search takes me: [your job or trade, how in demand it is right now, and how long it took to find work last time, e.g. "nurse, hospitals always hiring, last move took three weeks" or "marketing manager, my industry is cutting jobs, my last search took five months".]
- My cover when something goes wrong: [the amount you would pay yourself before insurance kicks in (called the deductible or excess) on health, car and home or renters cover, plus any sick pay or income protection through work. Write "none" or "not sure" rather than guessing.]
- My debts: [each one with the minimum monthly payment, the interest rate if you know it, and any date a 0% deal ends, e.g. "credit card 2,300 at 24%, minimum 70".]
- What is likely to break or come due in the next two years: [the lumpy costs, with a rough price if you know it, e.g. "car is nine years old and needs tyres soon, about 600", "laptop I work on is five years old", "dog is getting older", "annual car registration 250 in March". List anything that has surprised you in the past two years too.]
- What I have saved now, and where: [e.g. "3,000 in a savings account, 400 in my everyday account", or "nothing yet".]
- What I can move into savings each month: [a number you could keep up in a normal month, e.g. "500", and any month it changes, e.g. "nothing in December, an extra 800 when my tax refund lands".]
- Anything with a date on it: [e.g. "my contract ends in March", "baby due in June", "I want to go freelance next year". Write "nothing" if not.]

STEP 1: CHECK MY ESSENTIAL COSTS
List each essential cost back to me with its monthly amount. Convert any yearly or quarterly bill to a monthly figure and show the division. If any line looks like something I could pause in a lean month (streaming, a gym, eating out), ask whether it stays in the essential total rather than deciding for me. Add up the essential monthly total and show the addition. If a cost is still [NEED], stop here and ask.

STEP 2: SIZE THE SURPRISE-BILLS POT (the annoying, irregular costs)
This pot pays for irregular costs that land every year or two: car repairs, an appliance or laptop that dies, a vet bill, an insurance deductible, an annual bill. Build it from my own list: take every likely cost I named for the next 12 months with its price, add the single biggest deductible or excess I could be hit with, and show the sum. Leave out anything already counted in my essential monthly total. If a cost has no price, write [NEED: rough price of X] and leave it out of the total until I answer. If the result comes to less than half a month of my essential costs, use half a month as the floor and say you did. If I have a big known cost in months 13 to 24, list it separately as "save for this next".

STEP 3: SIZE THE LOST-INCOME POT (the costs of losing my income)
This pot covers my essential costs while I have no income, so it is a number of months multiplied by a monthly figure. First, add any costs that would start or go up if I lost my job to my essential monthly total, show that sum, and use the result as the monthly figure for this pot only. Then choose the months using my answers. Start at 3 months. The freelance rule and the job-search rule below each set a minimum. The dependants rule and the job-cuts rule add to the 3. Use whichever total is higher, and show each step.
- Dependants rule: if I am the only earner and someone relies on me, add 2 to 3 months to the 3.
- Job-cuts rule: if my industry is cutting jobs or my contract has an end date, add 1 to 2 months to the 3 and say why. If this rule and the dependants rule both apply, add both.
- Freelance rule: if my income is freelance, commission-heavy or seasonal, the minimum is 6 months and can go up to 12, and use my lowest month rather than my average when judging how hard a bad stretch would hit.
- Job-search rule: if my last job search took longer than 3 months, the minimum is that many months plus 2.
- If another income in the house covers the essentials on its own, you can go lower, and show me what that lower figure is.
- If another income covers only part of the essentials, show the monthly gap (the monthly figure minus that income), and show the target worked out on the gap next to the target worked out on the full figure. Tell me which one you used and why.
- If I told you about unemployment support I would get, show the target as (months × monthly figure) minus (support × the months it pays), with the sum. If I said "not sure", do not count it.
- If I have a health condition or a high health deductible, add that deductible on top, unless it is already counted in the surprise-bills pot.
Then give me three targets, each shown as months times that monthly figure. LOWER uses the low end of every range in the rules above and never drops below a minimum. MIDDLE uses the high end of every range. HIGHER is MIDDLE plus 3 months. If LOWER and MIDDLE come out the same, say so and give me two targets. For each one, say in one line what it would leave uncovered or what the extra months buy. Recommend one in two sentences with the reason taken from my answers, then ask which one I want and wait. Build Step 5 on my choice.

STEP 4: IF I HAVE EXPENSIVE DEBT
If any debt charges a high interest rate (as a rough line, anything in double figures), do not hide the trade-off. Using my numbers, lay out two orders side by side for the next 12 months: fill the surprise-bills pot first and then put extra money on the debt, or the other way round. Treat the monthly saving I gave as the only spare money, on top of my minimum payments. Show roughly what each order costs in interest and how exposed I am to a surprise bill in each. Then leave the choice to me: ask me which order I want and wait for my answer, then build Step 5 on that order. Say too that a nonprofit credit counsellor or a qualified adviser where I live can help me decide if it feels tight.

STEP 5: THE MONTH-BY-MONTH PLAN
Before the table, compare the monthly saving I gave with my take-home income minus my essential monthly total, and show that subtraction. If the saving is bigger than what is left, or I said I can save nothing, say so plainly, still give me both pot targets, and ask me for the smallest amount I could keep up, however small. Wait for my answer, then build the table on it.
Put my current savings into the surprise-bills pot first, because that pot gets used first, and any remainder into the lost-income pot. Then build a table with one row per month: the month, the amount into each pot, and each pot's running total. Fill the surprise-bills pot first, then the lost-income pot. Work out how many months each pot takes (the amount still needed divided by the monthly saving, rounded up) and show that division. Mark two milestones: the month the lost-income pot holds one full month of its monthly figure from Step 3, and the month both pots are full. If I chose debt first in Step 4, add a debt column and show the months the saving goes there.
- If my income varies, give me a rule as a share of each payment (for example "move 10% of every invoice the day it is paid") instead of a fixed amount, and work the table out on my lowest month.
- If reaching the target takes longer than 36 months, say so plainly and offer two ways to shorten it: a smaller first target to aim for, and how much more a month would bring it inside 36 months.
- If I named a month with no saving or an extra lump, put it in the table.
- If my current savings already cover both pots, say so, show the surplus, and skip the table.
- If the plan runs past 12 months, show the first 6 rows, then every 6th month, plus both milestone months.
- When the plan reaches the target, tell me the monthly saving is now free for me to decide on, and do not suggest where it goes.
- Add a refill rule: whenever I spend from a pot, the next months' savings go to refilling that pot before anything else.

STEP 6: WHAT EACH POT IS FOR
Using my own list, write three short lines for each pot: what it pays for, what it does not pay for (for example a holiday, or a sale), and what I do the day I have to use it. Keep it specific to me.

RULES FOR THE WHOLE CONVERSATION
- Never invent a cost, a price, an interest rate, a benefit, an insurance figure or a date. Write [NEED: what is missing] and ask.
- Show the working for every number, so I can check it on a calculator.
- If you can run code in this chat, do the arithmetic in code and say that you did. If you cannot, say so, and keep every sum simple enough for me to check by hand.
- Label anything estimated as an estimate.
- Do not recommend specific banks, accounts, funds or investments. If I ask where to keep the money, describe what to look for (separate from my everyday account, reachable within a day or two, covered by the scheme where I live that protects savings if a bank fails) and tell me to check the details myself.
- This is planning help, not financial advice. If my answers raise a question about tax, benefits, pensions, or debt I cannot keep up with, say it needs a qualified person where I live and carry on with the rest.
- Keep each section short, with labelled headings, and no pep talk.

CHECK YOUR OWN SUMS BEFORE YOU FINISH
1. Re-add my essential monthly total from the individual lines, from scratch, and confirm it matches the number you used.
2. Re-add each pot from its parts and re-multiply the lost-income pot.
3. Check the plan: my starting savings, plus my monthly saving times the number of months, plus any lumps, must reach at least the two pots added together. Show that sum.
4. If any number changed on the re-check, say which one and give the corrected figure.
5. List every [NEED] still open and every estimate you used, and name the one number in this plan you are least sure about.

What comes back

A run for a made-up single parent with one child. Every number here is invented.

Essential costs: 1,400 + 180 + 450 + 220 + 160 + 40 + 150 = 2,600 a month.

Surprise-bills pot: tyres and a service 600, a replacement laptop 900, and 500, the most they would pay themselves on an insurance claim, which comes to 2,000.

Lost-income pot: only earner, one child, last job search took four months, so six months: 6 × 2,600 = 15,600. The rules make six months the minimum here, so there is no lower option. The higher one is nine months, 23,400.

Debt: nothing in double figures, so Step 4 is skipped.

The plan: the 3,000 already saved fills the first pot and starts the second. At 500 a month, the remaining 14,600 takes 30 months, with one full month of costs saved by month 4.

Its own check: 3,000 + (500 × 30) = 18,000, which covers 2,000 + 15,600 = 17,600.

If it goes wrong

  • It skipped your questions and went straight to numbers. Reply: "Stop. Go back to BEFORE YOU CALCULATE and ask me the missing lines first."
  • The table runs long and cuts off. Reply: "Show the first 6 months, then every 6th month, plus both milestone months."
  • Your calculator disagrees with a total. Reply: "My calculator says [your figure] for the essential total. Redo Steps 1 to 5 from that number."
  • It finished without checking its sums. Reply: "Now run CHECK YOUR OWN SUMS BEFORE YOU FINISH."

Why two pots

The US investment firm Vanguard, in its emergency fund guidance (read 29 September 2026), splits savings by the kind of shock, a surprise bill or a loss of income, and the prompt follows it.

The surprise-bills pot

How big: Vanguard says at least half a month of living expenses. The prompt builds yours from what you expect to break in the next year, with half a month as the minimum.

How it is used: you dip into it every year or two, then refill it.

The lost-income pot

How big: Vanguard says three to six months of living expenses. The prompt picks your number of months from your job, your household, and how long your last job search took.

How it is used: ideally never, and only for the reasons you set in advance.

How many months is personal. In the US, the Bureau of Labor Statistics put the median time out of work at 11.4 weeks in August 2026, while the average was 26.3 weeks, because long searches drag it up. Your own last search is the better guide, so the prompt asks for it.

If the target looks impossible

Aim first at one full month of essential costs in the lost-income pot. The plan marks the month you get there.

The US consumer finance regulator, the CFPB, says in its emergency fund guide (read 19 September 2026) that even a small amount gives you some security, and that saving automatically is one of the easiest ways to keep going. So set the transfer to run on payday.

It also suggests saving all or part of a tax refund, so tell the prompt which month a lump lands.

The honest bit

  • This is planning help, and it cannot give you personal financial advice. Whether to pay down debt, invest or change jobs stays your call. Tax, benefits, and debt you cannot keep up with belong with a qualified person where you live.
  • It only knows what you type. Claude and ChatGPT cannot see your bank account or bills, so a cost you forget is a cost the plan leaves out. You type totals, and you never need to share an account number.
  • AI can get sums wrong, and sound certain doing it. The prompt shows every calculation so you can check it.
  • It does not know your country's rules. Unemployment support, sick pay and the scheme that protects your savings if a bank fails all differ by country, so the prompt only counts what you tell it applies to you.
  • Where you keep the money is a separate decision. The CFPB calls a bank or credit union generally one of the safest places, and suggests a dedicated account. Keep it apart from your everyday account, ideally as two accounts or two named pots.

Do it tonight

Fill in ABOUT ME, paste the prompt, and answer what it asks. Before you close the chat, set up one automatic transfer for the monthly amount you told it you can save, or the share of each payment it gave you if your income varies.

Run it again once a year, since bills creep up, on the day you spend from either pot, and whenever something big changes, such as a new job, a baby or a move. Type your current pot balances into the savings line each time.

A few quick questions

What counts as an emergency?

The CFPB suggests setting your own rules in advance, and gives car repairs, home repairs, medical bills and loss of income as the usual examples. Step 6 of the prompt writes yours.

Should the bigger pot cover all my spending or only essentials?

Only essentials, because after a job loss you would cut the rest, and that keeps the target reachable. If something would be hard to drop, like childcare you still need while you job hunt, count it as essential.

Should I pay off my credit card first?

The prompt leaves that to you. If a debt charges double-figure interest, Step 4 lays out both orders over 12 months, with the rough interest cost and how exposed each leaves you to a surprise bill, then waits for your pick.