20, 25 or 30 year mortgages: payments, interest and flexibility
Understand duration while holding principal and rate constant, then connect payments with your budget.
Read guide →Simuily / Learn and calculate
Emergency fund
Your scenario, explained
Change the inputs and explore the result over time. Figures are estimates under the assumptions you enter.
How it changes over time
Every year, in view
Year-by-year evolution
What the result can tell you
Understand before deciding
Emergency fund: setting a target and building your reserve
An emergency fund is money reserved for an important unexpected expense or a disruption to income. Its main purpose is to create room to respond. Start with the bills that would still need paying if less money arrived for a while: housing, food, utilities, necessary transport and other commitments. You do not need to predict the future precisely. You need to identify payments that are difficult to delay, resources you could draw on and the time you might reasonably need to adjust spending or restore income. That makes the target a practical planning decision rather than an impressive round number.
Calculate essential spending, not just income
Review several months of transactions and distinguish essential expenses from purchases that can wait. Include annual bills divided by twelve while retaining their actual due dates. If essential spending is 1,400 per month, three months of coverage would be 4,200 and six months would be 8,400. These illustrate coverage, rather than prescribing a universal rule. A suitable target depends on income stability, dependants, insurance, commitments and other support. Someone with seasonal earnings may need a different cash calendar from someone receiving a predictable monthly salary. The same reserve amount can therefore provide very different protection to different households.
Separate emergencies from predictable bills
A known annual bill does not become an emergency simply because it arrives infrequently. Create a separate provision for insurance, maintenance or tuition and contribute to it monthly. Otherwise, the emergency fund may appear to grow for months before disappearing into an expense that was already expected. It also helps to write a household definition of an emergency: which situations justify using the reserve and which belong in another budget category. The rule can be simple, but people sharing the money should agree on it before a stressful event forces a rushed decision.
Build the reserve in stages
A modest first milestone can cover urgent expenses without requiring the entire target immediately. If you can set aside 100 each month, reaching 600 takes six deposits without growth. You can then expand the target according to your risks and capacity. An automatic transfer after income arrives may support consistency, provided enough remains for immediate bills. With variable earnings, a cautious minimum contribution plus additional deposits when there is a surplus may be more realistic than a large fixed transfer that you repeatedly reverse. A reserve built gradually still provides useful protection during the building process.
One example, three possibilities
This is a hypothetical case. Compare effort, outcomes and timing without treating rates as forecasts. The figures use the same engine as the interactive calculator.
Scenario A
Essential monthly expenses: 1,280 · Months to cover: 6 · Available savings: 20,000 · Monthly contribution: 190 · Term in years: 10
- Reserve target: 7,680 EUR
- Reserve shortfall: 0 EUR
- Current months covered: 15.62
Scenario B
Essential monthly expenses: 1,280 · Months to cover: 6 · Available savings: 20,000 · Monthly contribution: 240 · Term in years: 10
- Reserve target: 7,680 EUR
- Reserve shortfall: 0 EUR
- Current months covered: 15.62
Scenario C
Essential monthly expenses: 1,280 · Months to cover: 6 · Available savings: 20,000 · Monthly contribution: 190 · Term in years: 15
- Reserve target: 7,680 EUR
- Reserve shortfall: 0 EUR
- Current months covered: 15.62
Questions that help explain your figures
What is starting capital?
It is the amount at the start of the calculation: an assigned savings balance or the stated loan principal, depending on the tool.
What is a recurring contribution?
It is new money added each period, separate from any growth generated by the balance.
How do simple and compound interest differ?
Simple interest does not include past interest in its calculation base. Compound interest allows previous interest to participate in later periods.
What is an effective annual rate?
It represents an equivalent one-year change under the stated convention. Its monthly equivalent is (1 + annual rate) raised to 1/12, minus 1.
Is the entered return guaranteed?
No. It is a model assumption, not a determination that a real product will provide that result.
Can I calculate at zero interest?
Yes. Savings become starting capital plus contributions, while a repayment loan divides principal by the number of payments.
Are contributions made at the beginning or end of the month?
These tools use contributions at the end of each month. A different timing convention can produce a different result from the same amounts.
What is a value in today’s money?
It adjusts a future balance using assumed inflation. It helps interpret purchasing power and does not automatically deduct taxes or fees.
Does switching currency convert my money?
No. It changes the displayed unit here. Actual conversion needs an exchange rate and its date.
Must language and country match?
No. You can read in English about a Spanish transaction or use Spanish for another market. Location determines local context.
Does the mortgage payment include all housing costs?
No. Principal and interest are separate from recurring costs you enter. Initial purchase expenses form another cost group.
What does repaying principal mean?
It means returning some of the borrowed money. Interest is a separate cost and does not itself reduce principal.
What is an amortisation schedule?
It breaks down payments, interest, principal repaid and remaining balance, under stated rate and timing assumptions.
What is LTV?
It is the loan divided by a reference property value. Simuily’s purchase model uses the price you enter, not a lender’s appraisal.
Can I use APR or TAE as the payment interest rate?
Do not automatically substitute them for the contractual rate. They are locally defined cost measures that can include more than periodic interest.
Is a longer term always better?
With principal and rate held constant, it usually lowers payments and raises total interest. Both effects should be shown.
What happens if the interest rate changes?
A constant-rate schedule no longer describes the whole contract. Model the reset and recalculate from the balance at that date.
Do lower payments and a shorter term save the same interest?
Not necessarily. In a comparable fixed-rate model, keeping payments and shortening the term normally saves more interest; lower payments release monthly cash.
What are closing or purchase costs?
They are expenses associated with completing a purchase or financing in a market. Separate them and check the country, region and transaction.
Are taxes calculated automatically when I select a country?
Not in these tools. Costs are manual. Entered costs should correspond to your local transaction.
Why can two calculators disagree?
Check nominal versus effective rates, contribution timing, payment frequency, rounding and included costs. Match conventions before comparing.
What is a scenario?
It is a set of assumptions. Comparing scenarios shows how results change, not the probability of each outcome.
What does the CSV download contain?
It includes the yearly table, entered values, currency, country context and calculation assumptions. Amounts are exported to two decimal places for review.
Do I need an account?
No. The tools, guides and CSV downloads are public and do not require an account.
Guides to understand each decision
A savings budget: turning income into sustainable contributions
Organise spending, annual bills and monthly headroom to find a contribution you can sustain.
Read guide →Amortization schedules: reading principal, interest and outstanding debt
Check each column and understand why a payment’s principal and interest components change over time.
Read guide →Compound interest with monthly contributions: how to read your results
Understand contributions, compounding conventions, inflation and scenario comparisons before relying on a projected balance.
Read guide →Useful terms on this page
Principal
The starting savings balance or loan amount used by the model.
Contribution
New money added to a balance.
Inflation
A change in the price level; its future value in a model is an assumption.
Payment
A recurring payment whose included components must be stated.
Amortisation
Repayment of loan principal.
Liquidity
The availability of money for use.
Term
The duration of a plan or loan.
Nominal interest
A rate quoted under a frequency and convention that must be stated.
Effective rate
An equivalent rate reflecting compounding over the stated period.
LTV
Loan divided by the specified reference property value.
Down payment
Money paid towards the purchase price, separate from other expenses.
Scenario
A set of assumptions used to compare outcomes.
Emergency fund
Money reserved for unexpected needs or an income interruption. Its size and access should reflect your expenses and circumstances.
Sinking fund
Money allocated to an expected expense with an approximate date, separate from an emergency reserve.
Nominal balance
An amount expressed in the currency and date of the calculation, without adjusting purchasing power for inflation.
Real balance
A balance adjusted by a price factor to express purchasing power at a reference date, not a separate bank account.
Percentage point
The difference between percentages: moving from a 3% rate to 4% is a one percentage point increase.
Fixed charge
A cost expressed as a money amount, distinct from a percentage of assets or a contribution.
Semiannual compounding
A nominal rate convention with compounding twice a year. Its monthly equivalent is (1 + annual rate/2) raised to 1/6, minus 1.
Outstanding balance
Principal still owed on a particular date. It differs from the sum of future payments, which may also contain interest.