How Much Extra Should You Pay on Debt? (Calculator With Examples)

You have $100 extra this month. Should it go to debt or savings? If your debt charges more than 7-8% interest, the answer is almost always debt. But how much difference does $100 actually make? More than you think.

The Impact of Extra Payments

Here is a $10,000 credit card at 24% APR, $300 minimum payment:

Extra/month	Total monthly	Payoff time	Total interest	Interest saved	Time saved
$0	$300	4y 4mo	$5,600	--	--
$50	$350	3y 2mo	$3,900	$1,700	1y 2mo
$100	$400	2y 7mo	$3,000	$2,600	1y 9mo
$200	$500	1y 11mo	$2,200	$3,400	2y 5mo
$300	$600	1y 6mo	$1,700	$3,900	2y 10mo
$500	$800	1y 1mo	$1,200	$4,400	3y 3mo

Look at the $100 extra column: $2,600 saved in interest. That means every $1 of extra payment returns $2.17 over the life of the debt. No savings account gives you that return.

The Same Math on Different Debt Types

Student loan ($25,000 at 5.5%, $265 minimum):

Extra/month	Payoff time	Total interest	Interest saved
$0	10 years	$6,900	--
$100	6.8 years	$4,300	$2,600
$200	5.2 years	$3,100	$3,800
$500	3 years	$1,600	$5,300

Car loan ($15,000 at 7%, $300 minimum):

Extra/month	Payoff time	Total interest	Interest saved
$0	5 years	$2,800	--
$100	3.8 years	$2,000	$800
$200	3 years	$1,600	$1,200
$500	1.8 years	$900	$1,900

Pattern: higher interest rates benefit more from extra payments. $100 extra on a 24% credit card saves $2,600. The same $100 on a 7% car loan saves $800. If you have both, put the extra toward the credit card first (avalanche method).

Where to Find Extra Money

You don't need to find $500. Finding $50-$100 is enough to change the math. Realistic sources:

• Cancel unused subscriptions: audit your credit card statement for recurring charges. Most people find $30-$80/month in things they forgot about.
• Reduce one meal out per week: $15-$25 saved per meal = $60-$100/month
• Switch phone plans: prepaid carriers charge $15-$30/month vs $70-$90 for major carriers
• Sell one thing per month: clothes, electronics, furniture. Even $50 from selling something you don't use goes straight to principal.

Use the budget calculator to split your income and find the extra. The 20% savings portion of the 50/30/20 rule should target high-interest debt before regular savings.

Lump Sum vs Monthly Extra

Got a tax refund, bonus, or gift? A one-time lump sum payment can be even more effective than monthly extras because it reduces principal immediately.

Example: $3,000 tax refund applied to a $10,000 credit card at 24%:

• Before lump sum: 4.3 years to payoff, $5,600 total interest
• After $3,000 lump sum: 2.3 years to payoff, $2,100 total interest
• Interest saved: $3,500

That $3,000 lump sum effectively earned you a $3,500 return. Try getting that from a savings account.

When NOT to Pay Extra on Debt

There are a few situations where extra debt payments aren't the best use of money:

• No emergency fund at all: build $1,000-$2,000 first, then attack debt
• Employer 401k match: if your employer matches 401k contributions, get the full match first. That is a 50-100% instant return.
• Very low interest debt (under 4%): a mortgage at 3.5% costs less than index fund returns (~10% historical average). Minimum payments may be the mathematically correct choice.