Buy Now Pay Later Calculator (True Cost)

Why "interest-free" still costs people money

Pay-in-4 splits a purchase into four biweekly installments at 0% — genuinely free when paid on time and used singly. The damage comes from the design: each plan feels small, plans stack invisibly across apps (Klarna + Afterpay + Affirm share no dashboard), and installments hit on a different rhythm than monthly budgets. The default example: three modest purchases = $490 committed, $122 every two weeks — 7% of a $3,800 take-home before rent exists.

Stacking, not interest, is the BNPL trap

The failure modes, priced

• Late fees: $7–10 per missed installment per plan; a bad two weeks with three plans ≈ $24–30, an effective APR in the hundreds on small purchases.
• Overdrafts: auto-debits landing before payday convert a free plan into a $35 bank fee.
• Credit reporting arrived: BNPL now increasingly reports to bureaus — missed installments damage scores like any missed loan payment.
• Spending inflation: retailers offer BNPL because baskets grow 20–40% at checkout when the price shows as "4 × $60".

The two-question rule before any plan

Could I buy this outright today? (If no — the plan is debt disguise, skip.) Do I have 2 or more plans already running? (If yes — finish one first.) BNPL used within those lines is a fine cash-flow tool; outside them it is a payday loan with better branding.