On-time total
$1,040.00
Debt & Credit
BNPL Stacking & True Cost Calculator
Compare multiple BNPL plans in one cashflow view and see stacking risk, peak payment windows, and late-fee impact.
Stacking Output
One-late total
$1,073.00
Repeated-late total
$1,098.00
Late-Fee Exposure
One missed cycle can materially increase total BNPL cost.
On-time total
$1,040.00
One-late total
$1,073.00
Repeated-late total
$1,098.00
Peak 7-day burden
$583.33
Cashflow Pressure Timeline
Compare due amounts under on-time vs late outcomes.
2026-022026-042026-05
On-time due
$113.33
One-late due
$121.33
Repeated-late due
$121.33
Stacking index (7-day burden / monthly income)0.05x
Peak period: 2026-03 ($583.33)
Cashflow Timeline
| Period | On time | One late | Repeated late | Installments |
|---|---|---|---|---|
| 2026-02 | $55.00 | $62.00 | $62.00 | 1 |
| 2026-03 | $583.33 | $593.33 | $608.33 | 7 |
| 2026-04 | $288.33 | $296.33 | $306.33 | 4 |
| 2026-05 | $113.33 | $121.33 | $121.33 | 2 |
Risk Flags
- Multiple installments cluster in single pay periods. Check due-date alignment.
How to use it
- Enter every active BNPL plan with amount, installment count, and start date, then add monthly take-home pay, fixed expenses, and paycheck dates. Due-date clustering matters more than the advertised 0% rate.
- Read the stacking index, peak payment month, and the on-time versus late-fee outcome. If BNPL payments plus fixed expenses leave less than about 10% of take-home as free cash, the setup is fragile.
- Several small installment plans can behave like a hidden debt payment even when each one feels manageable. A high stacking index means timing risk and cash-flow compression are the real problem.
- Pause new BNPL purchases until the peak month passes, or collapse the same spending into one payoff target in your budget. If revolving debt is also competing for cash, use the debt payoff strategy planner on those balances next.
- Re-run whenever you add a plan, change pay frequency, or miss an installment. Track peak-month obligations, number of overlapping plans, and the share of take-home already committed to installments.
AI Integrations
Contract, discovery endpoints, and developer notes for agent use.
Always available for agents
AI Integrations
Contract, discovery endpoints, and developer notes for agent use.
Tool contract JSON
https://aifinhub.io/contracts/bnpl-stacking-true-cost-calculator.jsonStable input and output contract for this exact tool.
Human review
People can use the browser page to sense-check outputs and charts, but agents should still execute against the contract and discovery endpoints.
- /agent-tools.json - machine-readable tool index.
- /llms.txt - human-readable model discovery guide.
- /.well-known/webmcp.json - WebMCP capabilities manifest.
- /.well-known/ai-plugin.json - plugin-style discovery manifest.
{
"tool": "bnpl_stack_true_cost",
"plans": [
{
"amount": 220,
"installment_count": 4,
"frequency_days": 14,
"start_date": "2026-02-28",
"late_fee": 7,
"grace_days": 2
}
],
"monthly_take_home": 4300,
"fixed_monthly_expenses": 2800,
"paycheck_dates": [
"2026-03-01",
"2026-03-15"
]
} Expand developer notes
Agent playbook
- Resolve BNPL Stacking & True Cost Calculator from /agent-tools.json and open its contract before execution.
- Validate inputs against the contract schema instead of scraping labels from the page UI.
- Open the browser page only when a person wants to review charts, assumptions, or related tools.
Agent FAQ
Should ChatGPT, Claude, or another agent click through the UI?
No. Start with /agent-tools.json, then follow the tool's contract URL. The page UI is for human review, not parameter discovery.
When do tools show Quick and Advanced?
Every tool opens in Quick Start first. Advanced Controls keeps the same scenario, reveals more assumptions or diagnostics, and every tool keeps AI integrations inline below the instructions.
When should an agent still open the browser page?
Open it when a human wants to sense-check the output, review the chart, or keep exploring related tools after the calculation finishes.
Questions people usually ask
Is BNPL really interest-free?
Not always in practice. Even when headline APR is 0%, missed or late payments can raise effective cost materially.
What does stacking index mean?
It measures the largest seven-day installment concentration relative to monthly take-home pay. Higher values indicate tighter cashflow windows.
Why include paycheck dates?
Due dates that cluster before paycheck dates increase default risk even when monthly totals seem manageable.
Is this professional advice?
No. Outputs are planning estimates only — not financial, tax, or investment advice.
Related Resources
Learn the decision before you act
Every link here is tied directly to BNPL Stacking & True Cost Calculator. Use the explanation, formula, examples, and benchmarks to pressure-test the calculator output from first principles.
How To Use
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