Loan Simulator

See how prepayments, rate changes, and extra payments affect your loan.

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Your Loan

EMI

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Total Interest

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Payoff

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Try a Change

Balance Over Time

Payment Breakdown

Principal—
Interest—
Interest is 0% of principal

Schedule

# Date Payment Principal Interest Balance

What Is a Loan Simulator?

A loan simulator goes beyond basic mortgage calculators. While a standard calculator shows your fixed monthly payment, a simulator lets you run what-if scenarios — testing how prepayments, rate changes, and payment increases affect your loan's total cost and payoff timeline. Think of it as a sandbox for your mortgage strategy.

Most US homeowners carry a 30-year fixed-rate mortgage. On a $300,000 loan at 7%, total interest over three decades exceeds $418,000 — more than the loan itself. That's where simulation becomes powerful. By modeling scenarios like extra monthly payments, lump-sum prepayments from a bonus or inheritance, refinancing to a lower rate, or gradually increasing payments as income grows, you can uncover strategies that save $50,000 to $150,000+ in interest and cut years off your mortgage.

How Simuloan Works

Enter your loan details — amount, interest rate, term, and start date. The engine instantly calculates your monthly payment, total interest, and payoff date using the standard amortization formula. Then add what-if events to your loan timeline. Each event recalculates the entire schedule, showing the exact impact in dollars and months saved.

Stack multiple events together and they compound — a rate drop plus extra payments often saves more than either change alone. The before/after comparison table shows exactly what changes: your EMI, end date, total tenure, and lifetime interest.

Scenarios You Can Simulate

  • Extra monthly payments — Even $100-200/month cuts years off a 30-year mortgage
  • Lump-sum prepayments — Model a bonus, inheritance, or tax refund applied to principal
  • Interest rate changes — Simulate refinancing or ARM adjustments
  • Payment increases — Model raising your EMI as salary grows over time

Why Simulate Instead of Calculate?

A calculator gives one answer. A simulator gives the range of possibilities. Real-life mortgages aren't static — rates change, bonuses happen, income grows. Simuloan models your loan as it actually evolves over time, not as a frozen snapshot from day one. You can toggle between reducing tenure (pay off early) or reducing EMI (lower monthly burden) to find the strategy that fits your life.

Simuloan is completely free, requires no signup, and runs entirely in your browser. No data is sent to any server — your financial information stays private on your device. Works for mortgages, car loans, personal loans, student loans, and any amortizing debt.

Who Uses Simuloan?

First-time homebuyers understanding what they're signing up for. Existing homeowners planning prepayment strategies. People considering refinancing who want to compare scenarios. Anyone managing multiple loans who wants to know which to pay down first. Financial advisors showing clients the math behind different payoff strategies versus investing the difference.

Frequently Asked Questions

How much does $100 extra a month save on a 30-year mortgage?▾
On a $300,000 mortgage at 6.5%, an extra $100 per month saves approximately $58,000 in total interest and cuts about 5 years off your 30-year term. At 7%, the savings jump to roughly $77,000 and nearly 6 years off. The key is that early extra payments have the most impact because they reduce the balance that future interest is calculated on.
What happens when you make an extra principal payment on a mortgage?▾
Extra principal payments reduce your loan balance directly. Since interest is calculated monthly on the remaining balance, a lower balance means less interest accrues each month. This creates a compounding effect — every dollar of extra principal saves several dollars of interest over the remaining life of the loan. Your required monthly payment stays the same, but the loan ends sooner.
Should I pay off my mortgage early or invest the extra money?▾
It depends on your mortgage rate versus expected investment returns. Prepaying gives a guaranteed, risk-free return equal to your rate — if you have a 7% mortgage, prepaying is like earning 7% risk-free. Stock markets historically return 8-12% but with significant volatility. If your rate is above 6%, prepaying is often the better risk-adjusted choice. Below 4%, investing typically wins. Many financial planners recommend splitting the difference.
How to pay off a 30-year mortgage in 15 years?▾
To cut your 30-year mortgage in half, you need to roughly double your principal payment. On a $300,000 loan at 7%, your standard payment is about $1,996. To pay it off in 15 years, you'd need to pay approximately $2,696 — about $700 extra per month. Alternatively, you can start smaller and increase annually: adding 10% more each year as income grows gets you close to the same result with less upfront strain.
Does one extra mortgage payment a year make a difference?▾
Yes — a significant one. Making one extra payment per year (equivalent to your regular monthly amount) on a 30-year mortgage typically cuts 4 to 5 years off the term and saves tens of thousands in interest. On a $300,000 loan at 7%, one extra annual payment saves approximately $65,000 and pays off the loan in about 25 years instead of 30. The biweekly payment strategy achieves the same effect automatically.
Do extra mortgage payments go to principal or interest?▾
Extra payments should go entirely to principal, but you must explicitly tell your lender. Most lenders have an "additional principal" field on their payment form. If you don't specify, some servicers may apply it toward the next month's regular payment (covering both interest and principal), which reduces the benefit. Always confirm with your servicer that extra amounts are applied directly to principal.
What is a mortgage recast and is it worth it?▾
A mortgage recast is when you make a large lump-sum payment toward principal and your lender recalculates your monthly payment based on the new lower balance — keeping your interest rate and remaining term the same. It typically costs $150-$500 versus $2,000-$6,000 for a refinance. It's worth it when you want lower monthly payments without changing your rate (especially if your current rate is good). Use this simulator's lump sum feature with "Reduce EMI" mode to preview recast savings.
Is it worth paying extra on a mortgage with a low interest rate?▾
If your rate is below 4%, the math often favors investing extra cash instead — especially in a diversified stock portfolio with a long time horizon. You'd likely earn more than 4% over 10-20 years. However, the psychological benefit of being debt-free is real and can't be measured in spreadsheets. Above 5-6%, prepaying almost always wins on a risk-adjusted basis because matching that return risk-free is difficult.
What is the fastest way to pay off a mortgage?▾
The fastest strategies, in order of impact: (1) Large lump-sum prepayments when you get bonuses, tax refunds, or windfalls — applied early in the loan. (2) Increase your payment every year by 5-10% as income grows. (3) Switch to biweekly payments (26 half-payments = 13 full payments per year). (4) Refinance to a shorter term if rates are lower. Combining multiple strategies produces the best results — use this simulator to stack them and see the combined effect.
How much interest do you save by paying biweekly instead of monthly?▾
Biweekly payments result in 26 half-payments per year, which equals 13 full monthly payments instead of 12. That one extra payment per year typically saves $50,000-$90,000 in interest on a $300,000-$400,000 mortgage and cuts 4-6 years off the term. The exact savings depend on your rate and balance. Not all lenders offer true biweekly processing — some hold biweekly payments and apply them monthly, which eliminates the benefit.