Free Student Loan Payment Planner: Compare SAVE vs IBR Monthly Payments

A free student loan payment planner answers one question that servicer statements never answer directly: if I switch plans, what will I actually pay every month? For most federal borrowers the real decision is SAVE versus IBR, because those are the two income-driven plans with the widest eligibility. The catch is that the two plans do not use the same arithmetic, so the same salary can produce two very different monthly numbers — and the gap widens or narrows depending on your family size, your loan balance, and whether any of your debt is from graduate school.

This guide walks through the exact math the planner runs, then works a full example so you can sanity-check any number a calculator hands you.

What "Income-Driven" Actually Means

Both SAVE and IBR start from the same idea: a slice of your income is treated as untouchable, and you pay a percentage of what is left. That untouchable slice is called the protection allowance, and it is built from the federal poverty line for your family size.

The planner uses the 2024 HHS poverty guidelines for the 48 contiguous states: $15,060 for a household of one, plus $5,380 for each additional person. Then it multiplies that figure by a plan-specific factor.

That table is the whole game. Everything else is multiplication and division.

Step 1 — Find Your Discretionary Income

Discretionary income is your adjusted gross income minus the protection allowance. If the result is negative, it is treated as zero, which means your required payment is zero.

For a single borrower earning $55,000:

• SAVE allowance: $15,060 × 2.25 = $33,885 → discretionary income = $55,000 − $33,885 = $21,115
• IBR allowance: $15,060 × 1.50 = $22,590 → discretionary income = $55,000 − $22,590 = $32,410

Same salary, same loans, but IBR sees $11,295 more of your income as spendable. That single difference is why the IBR payment comes out higher.

Step 2 — Apply the Payment Rate

Divide the discretionary figure by twelve to get a monthly base, then apply the plan's percentage.

For the borrower above, with $35,000 of undergraduate debt at 6.8%:

• SAVE: $21,115 × 5% ÷ 12 = $87.98 per month
• IBR: $32,410 × 10% ÷ 12 = $270.08 per month
• Standard 10-year plan: $402.78 per month

The planner prints all three side by side because the comparison is the point. SAVE is roughly a third of the IBR payment here, and about a fifth of the standard payment.

Step 3 — Check the Cap Before You Trust the IBR Number

IBR has a feature SAVE does not: a ceiling. Under the new-borrower version of IBR, your calculated payment can never exceed what you would have paid on a standard 10-year plan. Above that line, your "income-driven" payment stops tracking income altogether.

That cap flips the ranking at higher balances. Take the same $55,000 salary with a larger loan:

• $35,000 balance → 10-year cap is $402.78, raw IBR payment is $270.08, so the cap does not bind and you pay $270.08
• $60,000 balance → cap rises to $690.48, raw payment is still $561.75, cap still does not bind
• $100,000 balance → cap rises to $1,150.80, but you still pay $561.75 because IBR tracks income, not balance

Read that third row twice. Doubling the balance from $60,000 to $100,000 leaves the IBR payment unchanged. Only the term and the eventual forgiven balance move. SAVE behaves the same way, but with no cap at all — its payment can, in theory, exceed the standard payment if your income is high enough relative to a small balance.

Why Family Size Moves SAVE More Than IBR

Because SAVE multiplies the poverty line by 2.25 and IBR by 1.50, each additional household member is worth more to a SAVE borrower. Holding the $55,000 salary and $35,000 balance constant:

At three dependents the SAVE payment reaches zero on this salary, because the protection allowance of $58,095 now exceeds the income that counts. On IBR, with the smaller 150% factor, that same household would still owe a payment. If your household size is the thing that changes most often in your life, the planner is worth re-running every time it does.

Step 4 — Watch the Graduate Share Field

SAVE charges 5% of discretionary income on undergraduate loans and 10% on graduate loans, blended by how much of your balance came from grad school. This is not a rounding detail.

• All undergraduate: 5% rate, payment $87.98, forgiveness after 20 years
• Half graduate: 7.5% blended rate, payment $131.97, forgiveness after 25 years
• All graduate: 10% rate, payment $175.96, forgiveness after 25 years

The term change matters as much as the payment change. Five extra years of payments is sixty extra months, and it also means five more years of balance growth to be forgiven.

Step 5 — Understand What "Forgiveness" Means in the Output

The planner projects your balance forward at your loan's interest rate while subtracting your fixed payment. When the payment is smaller than the monthly interest, the balance grows, and the projected end balance is reported as the forgiven amount.

For the $35,000 / 6.8% / $87.98 SAVE case, that projection returns a forgiven balance of about $91,111 after twenty years, with $21,115 paid along the way. Treat that as a directional estimate, not a promise, for three reasons:

• The model assumes your income never changes for twenty years. Every real borrower's income changes, and each year's payment is recalculated from the newest tax return.
• The model does not apply an interest subsidy. Real SAVE cancels unpaid interest that your payment does not cover, so the true forgiven balance is typically smaller than the projection.
• Forgiveness under current law is excluded from federal income tax through 2025; after that the tax treatment depends on legislation that has not been settled.

A planner that told you a single confident forgiveness number would be lying to you. The honest output is a range, and the useful part of the tool is the monthly payment, which is knowable today.

What the Planner Deliberately Leaves Out

Every calculator draws a boundary. This one draws it around the federal rules that are stable and arithmetic, and leaves out the parts that are procedural:

• Annual recertification. The payment is only valid for twelve months. Miss the recertification deadline and your servicer can reset you to a standard payment.
• Married filing separately. The planner takes one AGI. Filing separately can exclude a spouse's income, which changes discretionary income substantially and is not modeled.
• PSLF interaction. If you work for a qualifying employer, forgiveness may arrive after 120 payments instead of 240 or 300, which changes the entire calculation.
• Private loans. These plans are federal-only. The tool disables the income-driven section and points you to refinancing instead, which is the honest answer.
• Interest capitalization events. Consolidation, leaving a plan, and certain deferments can add unpaid interest to principal. The projection assumes a smooth path.

How to Use the Planner in Five Minutes

Start with the four numbers you can read off your servicer statement and last tax return: balance, interest rate, remaining term, and loan type. Set the loan type to federal, or the income-driven panel will correctly disable itself.

Then enter your AGI and your household size. If you have any graduate loans, set the graduate share field rather than leaving it at zero — a half-graduate borrower on this example pays $43.99 more per month than the calculator shows at a zero graduate share, and carries five extra years before forgiveness.

Finally, read the comparison table rather than a single number. The decision you are making is not "which plan is cheapest this month" but "which trade-off between a low payment and a long term do I want." SAVE on this example costs $21,115 over twenty years with a large projected forgiveness balance and a real risk that the projection shrinks. IBR costs $63,470 over the same twenty years with nothing left to forgive. The standard plan costs $48,334 and ends in ten years with no uncertainty at all.

None of those three answers is wrong. The planner's job is to put all three in front of you with the same inputs, so you are choosing between plans rather than between marketing pages. Run your own numbers, write down the monthly figure, and re-run it every time your AGI or your household size changes — those two fields drive everything else in the output.