Discount / Sale Price + Tax Calculator
We stack percent and flat discounts, then apply sales tax to reveal the real checkout price. See savings by item and for your whole basket.
Your deal (updates live)
Checkout breakdown
Results interpretation: who benefits
- Big percent off? We apply percent discounts first so stacked percents compound (e.g., 20% then 10% ⇒ 28% off the original, not 30%).
- Flat coupon per basket vs per item: Toggle “per item” to reflect $X off each unit (useful for grocery and apparel promos).
- Tax rules vary: We apply sales tax to the discounted subtotal, which is the most common retail practice.
- Unit economics: Per-item results help compare multi-pack deals or sizes quickly.
Use cases & examples
Example 1 — Stacked percent + flat: $80 item, qty 2, 20% off, extra $10 coupon (basket), 8.5% tax. We take 20% off the $160 subtotal ⇒ $128, then minus $10 ⇒ $118. Tax = $10.03; final ≈ $128.03.
Example 2 — Per-item coupon: Same as above but $5 per item coupon. After 20%, $160 → $128, then −$10 per item (×2) ⇒ $108. Tax 8.5% ⇒ $117.18.
Example 3 — Percent-only doorbuster: $49.99 item, qty 1, 35% off, 7% tax. Discounted subtotal = $32.49; tax ≈ $2.27.
How our discount calculator works
Formula, order of operations & assumptions
1) Subtotal: listSubtotal = price × quantity.
2) Primary discount: If percent, we compute listSubtotal × d1%. If flat, we subtract up to the subtotal.
3) Extra coupon (stacked): If percent, we apply to the post-discount amount. If flat, we subtract either once per basket or once per item (your toggle).
4) Sales tax: tax = discountedSubtotal × tax%. Final total = discountedSubtotal + tax.
You save is calculated versus “list + tax,” which reflects the price you’d pay without discounts.
We don’t model state-specific tax quirks (e.g., clothing exemptions or “tax on pre- or post-coupon” edge cases). Treat outputs as planning estimates.
Smart discount shopping: our guide to stacking coupons, sale prices, and tax
We built our discount calculator to answer a surprisingly tricky question: “What will we really pay at the register?” Every shop runs promotions differently—percent off the tag, flat coupons, buy-more-save-more, in-cart markdowns, and layered promo codes. Add sales tax and multi-unit baskets and it’s easy to misjudge the deal. Our goal is to give you a truthful, transparent out-the-door total and the savings behind it.
Start with the true baseline. List price times quantity is the anchor. When a retailer markets “30% off + extra $10,” it’s tempting to mental-math the result, but the order of operations matters: percent discounts compound, and flat coupons may be per basket or per item. We expose both so the calculation mirrors the store’s rules.
Understand compounding percent discounts. If you see “20% off plus 10% off,” that’s not 30% off the original. It’s sequential: the second 10% applies to the already-discounted price. Equivalent combined discount = 1 − (1 − .20) × (1 − .10) = 28%. Our engine follows that convention because that’s how checkout systems work.
Flat coupons are powerful in low-price items. Ten dollars off a $20 item is a 50% cut; on a $200 item it’s only 5%. If your coupon is “per item,” a multi-pack can be a bigger win than one large item. We include a per-item toggle so your basket math is honest.
Sales tax is a real cost. Most jurisdictions tax the discounted subtotal, not the list. A few edge cases tax before coupons or exempt categories like groceries or kids clothing. Our design assumes the widely used “tax after discounts” model so results match typical receipts.
Compare unit economics. The “per item before/after tax” outputs make it easy to evaluate unit-price stickers, warehouse-club bundles, and “buy two get one” promotions. If the per-item after-tax cost is lower for one option, that’s the better deal—even when the headline percent off looks smaller.
When stacking promos, watch for caps. Some coupons cap maximum dollars off or exclude certain brands. If your real checkout differs, the POS probably applied a cap or changed the order of operations. Adjust the inputs or split your basket to reflect those rules.
Deal-day strategy. On big sale days, combine retailer percent offs with fixed-value manufacturer coupons. Because our model applies percents first, a fixed coupon pulls from a smaller subtotal—so stacking percent then flat tends to save more than the reverse.
Make it shareable. Use “Copy link with inputs” to save your scenario for later or share it with a friend who’s hunting the same promo. We encode the entire basket state in the URL.
Whether you’re planning a seasonal haul or checking a single line item, our calculator is designed to replace guesswork with clean math. You’ll know the real total, the real savings, and the per-item value—before you tap “Place order.”
FAQ: discounts, coupons, and sales tax
Do percent discounts add or multiply?
They multiply (compound). 20% off plus 10% off equals 28% total off the original, not 30%.
Is sales tax applied before or after discounts?
Most retailers tax the discounted subtotal. A few jurisdictions have special rules; our outputs assume tax after discounts.
What does “per item coupon” mean?
A flat coupon that applies to each unit (e.g., $5 off each shirt). If unchecked, the flat amount is taken once per basket.
How do you compute 'You save'?
We compare your final total against 'list price + tax'—the amount you’d pay without discounts.
Can I stack multiple extra coupons?
Enter the combined percent as one value or a single flat amount that reflects the best coupon you can apply. Many stores allow only one extra code per order.
Why doesn’t my receipt match exactly?
Some POS systems round at the line level or enforce brand/category exclusions and caps. Mirror those rules with the per-item toggle or by adjusting values.