https://howlane.com/moneymath/The math behind everyday money decisions, worked out step by step.enMon, 19 Oct 2026 12:00:00 GMThttps://howlane.com/moneymath/how-federal-student-loan-interest-accrues-daily/https://howlane.com/moneymath/how-federal-student-loan-interest-accrues-daily/Mon, 19 Oct 2026 12:00:00 GMTDirect Loans use simple daily interest: balance x rate / 365.25 x days elapsed. Payments cover interest first, and unpaid interest can capitalize.https://howlane.com/moneymath/what-a-health-fsa-really-saves-you/https://howlane.com/moneymath/what-a-health-fsa-really-saves-you/Sun, 18 Oct 2026 12:00:00 GMTA health FSA skips income and payroll tax, up to $3,400 in 2026. At a 22% bracket that saves $1,008, but you must use about 70% of it to come out ahead.https://howlane.com/moneymath/marginal-vs-effective-tax-rate-2026-example/https://howlane.com/moneymath/marginal-vs-effective-tax-rate-2026-example/Sat, 17 Oct 2026 12:00:00 GMTA raise cannot cut take-home pay by crossing a bracket. IRS 2026 rates on $60,000 of taxable income give a 22% marginal and 13.19% effective rate.https://howlane.com/moneymath/cd-early-withdrawal-penalty-what-it-costs/https://howlane.com/moneymath/cd-early-withdrawal-penalty-what-it-costs/Fri, 16 Oct 2026 12:00:00 GMTBanks must disclose how a CD penalty is calculated. Math for a $10,000 CD with a 180-day interest penalty, and when breaking it for a higher rate pays.https://howlane.com/moneymath/dollar-cost-averaging-the-math-behind-average-cost/https://howlane.com/moneymath/dollar-cost-averaging-the-math-behind-average-cost/Wed, 14 Oct 2026 12:00:00 GMTInvesting a fixed amount on a schedule buys more shares when prices dip. See why your average cost lands below the average price, and when it fails.https://howlane.com/moneymath/how-credit-card-interest-is-calculated-average-daily-balance/https://howlane.com/moneymath/how-credit-card-interest-is-calculated-average-daily-balance/Wed, 14 Oct 2026 12:00:00 GMTMost card issuers charge interest daily on your average daily balance. See how the daily rate, balance, and grace period become one dollar figure.https://howlane.com/moneymath/how-fdic-insurance-limits-add-up-with-interest-and-ownership-categories/https://howlane.com/moneymath/how-fdic-insurance-limits-add-up-with-interest-and-ownership-categories/Wed, 14 Oct 2026 12:00:00 GMTFDIC insures $250,000 per depositor, per bank, per ownership category, counting accrued interest. See worked examples for CDs, IRAs, and trusts.https://howlane.com/moneymath/how-loan-amortization-works-car-loan-example/https://howlane.com/moneymath/how-loan-amortization-works-car-loan-example/Wed, 14 Oct 2026 12:00:00 GMTEach loan payment is split between interest and principal, and the split shifts over time. See the numbers for a $28,000 car loan over 60 and 72 months.https://howlane.com/moneymath/how-the-i-bond-interest-rate-is-calculated/https://howlane.com/moneymath/how-the-i-bond-interest-rate-is-calculated/Wed, 14 Oct 2026 12:00:00 GMTThe I bond rate blends a fixed rate and an inflation rate with a set formula. See the formula, the current numbers, and what happens in deflation.https://howlane.com/moneymath/is-a-balance-transfer-worth-the-fee/https://howlane.com/moneymath/is-a-balance-transfer-worth-the-fee/Wed, 14 Oct 2026 12:00:00 GMTA 0% balance transfer still costs a fee up front. See how to weigh that fee against the interest you would otherwise pay, and the traps to avoid.https://howlane.com/moneymath/payday-loan-apr-how-15-per-100-becomes-almost-400-percent/https://howlane.com/moneymath/payday-loan-apr-how-15-per-100-becomes-almost-400-percent/Wed, 14 Oct 2026 12:00:00 GMTA payday loan fee looks small in dollars, but for two weeks it works out to an APR near 400%. See the conversion step by step and what rollovers add.https://howlane.com/moneymath/savings-bond-interest-taxes-report-yearly-or-wait/https://howlane.com/moneymath/savings-bond-interest-taxes-report-yearly-or-wait/Wed, 14 Oct 2026 12:00:00 GMTEE and I bond interest is federal-taxable, never state-taxable, and you choose when to report it. A $1,000, 10-year example compares the two ways.https://howlane.com/moneymath/ee-bond-doubling-guarantee-what-2-40-percent-really-means/https://howlane.com/moneymath/ee-bond-doubling-guarantee-what-2-40-percent-really-means/Wed, 14 Oct 2026 12:00:00 GMTTreasury guarantees an EE bond is worth at least twice its price after 20 years, even at a 2.40% rate. The guarantee implies about 3.53% a year.https://howlane.com/moneymath/treasury-bill-discount-rate-vs-investment-rate/https://howlane.com/moneymath/treasury-bill-discount-rate-vs-investment-rate/Wed, 14 Oct 2026 12:00:00 GMTT-bill auction results show two rates, and the investment rate is always the higher one. See the Treasury's own formulas and what each means in dollars.https://howlane.com/moneymath/what-it-costs-to-cash-a-savings-bond-early/https://howlane.com/moneymath/what-it-costs-to-cash-a-savings-bond-early/Wed, 14 Oct 2026 12:00:00 GMTEE and I bonds can be cashed after 12 months, but before 5 years you lose the last 3 months of interest. Here is the dollar cost on a $1,000 bond.https://howlane.com/moneymath/why-bond-prices-fall-when-interest-rates-rise/https://howlane.com/moneymath/why-bond-prices-fall-when-interest-rates-rise/Wed, 14 Oct 2026 12:00:00 GMTA bond's fixed coupon looks worse when new bonds pay more, so its price drops. See the math on 2, 10, and 30-year bonds when rates move one point.https://howlane.com/moneymath/real-vs-nominal-return-how-to-subtract-inflation/https://howlane.com/moneymath/real-vs-nominal-return-how-to-subtract-inflation/Mon, 12 Oct 2026 12:00:00 GMTA savings rate counts dollars gained; the real return counts what they can buy. Here is the exact formula, worked with current federal data.https://howlane.com/moneymath/apr-vs-apy-what-the-difference-means-in-dollars/https://howlane.com/moneymath/apr-vs-apy-what-the-difference-means-in-dollars/Sun, 11 Oct 2026 12:00:00 GMTAPR and APY sound alike but answer different questions. See how each is defined in federal rules and what the gap is worth on savings and card balances.https://howlane.com/moneymath/how-investment-fees-compound-over-time/https://howlane.com/moneymath/how-investment-fees-compound-over-time/Sun, 11 Oct 2026 12:00:00 GMTA 1% fee sounds tiny, but it is charged every year on a growing balance. Here is how ongoing fees reduce long-term results, using federal examples.https://howlane.com/moneymath/inflation-explained-with-a-grocery-receipt/https://howlane.com/moneymath/inflation-explained-with-a-grocery-receipt/Fri, 09 Oct 2026 12:00:00 GMTThe BLS Consumer Price Index tracks a weighted basket of prices each month. See it with a $150 grocery cart and an illustrative 3% yearly inflation rate.https://howlane.com/moneymath/the-rule-of-72-and-where-it-fails/https://howlane.com/moneymath/the-rule-of-72-and-where-it-fails/Fri, 09 Oct 2026 12:00:00 GMTDivide 72 by the rate to estimate doubling time. Compare it with the exact ln(2)/ln(1+r) formula and see how far off the shortcut gets at higher rates.https://howlane.com/moneymath/what-a-credit-cards-minimum-payment-really-costs-you/https://howlane.com/moneymath/what-a-credit-cards-minimum-payment-really-costs-you/Fri, 09 Oct 2026 12:00:00 GMTThe federal rule behind the minimum payment warning on your statement, and a worked example showing how much extra time and interest it adds.https://howlane.com/moneymath/what-saving-100-a-month-really-adds-up-to/https://howlane.com/moneymath/what-saving-100-a-month-really-adds-up-to/Fri, 09 Oct 2026 12:00:00 GMTSaving $100 a month at an assumed 7% return, compounded monthly, shown for 10, 20, 30 and 40 years, with the assumption stated up front.