Cost of Trade Credit Calculator and Formula

A cost of trade credit calculator estimates the annualized cost of giving up a supplier’s early-payment discount in exchange for paying later. Enter the discount, the net payment period, and the discount deadline; the calculator returns the implied annual percentage rate (APR) and the dollar discount forgone on an invoice.

Formula

The calculator uses the standard simple annualized-cost formula for trade credit terms written as “d% discount if paid by day e; otherwise the full amount is due by day n.” The buyer effectively pays the discount amount to keep the money for the additional days between the early-payment deadline and the net due date.

Implied annual cost (%) = [d ÷ (100 − d)] × [365 ÷ (n − e)] × 100

• d is the discount rate as a percentage of the invoice.
• n is the net payment period, in days after the invoice date.
• e is the early-payment deadline, in days after the invoice date.
• n − e is the extra time for which payment is deferred by declining the discount.
• Invoice amount is the dollar value used to calculate the discount forgone; it does not affect the APR result.

The fraction d ÷ (100 − d) compares the discount surrendered with the cash payment that would have secured it. Multiplying by 365 ÷ (n − e) scales that short-period cost to a simple annualized rate. The formula assumes a 365-day year and does not compound the cost repeatedly.

Worked Example

Using the calculator’s default values—2% discount, payment due in 30 days, discount deadline at 10 days, and a $10,000 invoice—the buyer has 20 extra days of payment time by declining the discount.

1. Calculate the discount as a share of the discounted payment: 2 ÷ (100 − 2) = 2 ÷ 98 = 0.020408.
2. Annualize the 20-day period: 365 ÷ (30 − 10) = 365 ÷ 20 = 18.25.
3. Multiply and express as a percentage: 0.020408 × 18.25 × 100 = 37.2449%, or 37.24% implied annual cost.
4. Find the discount forgone: $10,000 × 2 ÷ 100 = $200.

The result means that, under this simplified comparison, declining the $200 discount to hold the invoice cash for 20 more days implies a simple annualized financing cost of 37.24%. It is not an interest charge that the supplier necessarily bills, nor does it mean the invoice grows by 37.24%.

Assumptions

• The discount applies to the full invoice amount entered, with no excluded items or partial-payment rules.
• The invoice date starts both day counts, and the additional credit period is net days minus discount days.
• The annualization uses 365 days and simple proportional scaling; it does not compound.
• The comparison excludes late-payment charges, taxes, transaction fees, cash-management effects, and any other contract terms.

How Trade Credit Cost Works

Trade credit is a supplier’s agreement to let a business receive goods or services before paying the invoice. Terms such as “2/10, net 30” commonly mean a 2% discount is available if the invoice is paid within 10 days; otherwise, the full invoice is due within 30 days. The exact meaning depends on the supplier’s written terms, so confirm the dates and conditions rather than relying on shorthand alone.

Choosing the later due date preserves cash temporarily, but forgoing a discount has an economic cost. In the example, paying $9,800 on day 10 obtains the discount; paying $10,000 on day 30 retains the $9,800 for 20 more days but gives up $200. The calculator expresses that trade-off as an annualized rate to make it easier to compare with other financing costs. Annualization is a comparison convention, not a prediction of what the business will pay over a year.

How to Use and Interpret the Result

• Read the supplier’s terms and enter the actual discount percentage and the two applicable day counts.
• Enter the invoice amount to estimate the dollar value of the discount you would forgo. If only part of the invoice qualifies, use the eligible amount instead.
• Check that the discount deadline is earlier than the net due date. The inputs must produce a positive difference; otherwise, there is no meaningful extra credit period for this formula.
• Compare the annualized result with a relevant, known cost of funding only after accounting for differences in fees, timing, and terms. The calculator does not supply or verify those comparison figures.

A larger discount usually raises the calculated cost of declining it, while a longer gap between the early deadline and final due date lowers the annualized figure for the same discount. The invoice amount changes the dollar discount, not the percentage cost. A percentage result can therefore look high even when the actual dollar amount is modest; use both outputs to understand the scale.

Limits and Common Mistakes

This estimate does not model the business’s cash-flow needs, the value of retaining cash, supplier relationships, changing invoice balances, or the consequences of paying late. It assumes the buyer can pay on the early date and receive the stated discount. If payment is delayed beyond net terms, the formula is not a late-payment-cost calculator.

• Confusing the two periods: use the difference between the net due date and discount deadline, not the full net period. For 2/10, net 30, the relevant extra period is 20 days.
• Entering a decimal instead of a percent: enter 2 for a 2% discount, not 0.02.
• Ignoring eligibility: verify whether the discount applies to the whole invoice, freight, taxes, or only certain items under the supplier’s terms.
• Treating APR as a bill: the annualized rate is an analytical comparison, not necessarily a contractual interest rate charged by the supplier.
• Overlooking day-count conventions: the calculator uses 365 days. A supplier or other comparison may use different dates or conventions, which can change the result slightly.

Frequently Asked Questions

What is the cost of trade credit?
The cost is the economic value of the benefit surrendered to pay later, often measured as the discount forgone. For discount terms, a common method annualizes that short-term cost as a percentage.

How do I calculate the cost of 2/10, net 30?
Subtract 10 from 30 to get a 20-day extension, then calculate (2 ÷ 98) × (365 ÷ 20) × 100. The result is about 37.24% using a 365-day year and simple annualization.

Does the invoice amount affect the trade credit APR?
No. Under this formula, the discount percentage and the number of extra days determine the annualized rate. The invoice amount determines the dollar value of the discount forgone.

Is the calculated trade credit cost the same as interest?
No. It is an implied annualized cost of declining a discount, useful for analysis. The supplier may not charge interest if the invoice is paid by its stated net due date.

What if there is no early-payment discount?
This discount-based formula does not apply when the discount is zero. Other costs of supplier credit, such as explicit financing charges or late fees, require their own terms and calculations.

This result is an estimate for education; the supplier’s invoice and written terms determine the actual amounts and deadlines.

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in d | Discount rate | % | 2 | 0.01 | 99
in n | Net payment period | days | 30 | 1 | 365
in e | Early-payment period | days | 10 | 0 | 364
in a | Invoice amount | $ | 10000 | 0 | 100000000
out apr | Implied annual cost | % | (d / (100 - d)) * (365 / (n - e)) * 100 | 2
out loss | Discount forgone | $ | a * d / 100 | 2