How to Compare Voucher Codes by Real Saving: A UK Discount Terms Checklist

Overview

When several promo codes appear at checkout, it is tempting to choose the one with the largest headline discount. That can be misleading. A 20% code may have a strict maximum saving, while a smaller discount could apply to more of your basket. A free delivery code may also beat a percentage discount if the order is small or delivery is expensive.

The most useful comparison is the final cost of the order, not the wording used to promote the code. Before choosing between voucher codes, write down the basket total, delivery charge, any cashback or loyalty reward, and the conditions attached to each offer. Then compare the likely final saving on the items you actually want to buy.

This approach works for retailer vouchers, online discount codes, free delivery codes and targeted offers such as a student discount or NHS discount. Eligibility-based offers should only be used if you meet the stated requirements, and retailer terms should always take priority over a description on a voucher page.

For a quick calculation, you can use the Voucher Savings Calculator to compare an instant discount, cashback offer and sale price using the same basket.

Checklist by scenario

When comparing percentage discounts

• Check the maximum saving. A code such as “20% off” may only reduce the price up to a stated cap. Apply the percentage to the eligible part of your basket, then compare the result with the cap.
• Check what counts as eligible. Some codes exclude selected brands, products, categories, gift cards, subscriptions or items already reduced. Remove excluded products from your calculation.
• Check the minimum spend. Confirm whether the threshold is measured before or after other discounts, and whether delivery charges count towards it. Do not add unwanted items simply to qualify for a code.
• Compare the discount with the basket size. A fixed-value code may save more than a percentage code on a smaller order, while a percentage code may become more useful on a larger eligible basket.

When comparing fixed-value codes

• Calculate the effective percentage. Divide the fixed saving by the eligible product total. This makes a £10 discount on a £60 basket easier to compare with a percentage offer.
• Look for a minimum spend and expiry date. A fixed-value code may look generous but be unavailable for your order or no longer valid when you are ready to pay.
• Check whether the saving is applied before delivery. A code that reduces the product total may still leave the full delivery fee payable.

When comparing free delivery codes

• Record the normal delivery charge. The value of the code is usually the delivery cost it removes, subject to the retailer’s terms.
• Check the delivery method. A code may cover standard delivery but not express, timed or premium services.
• Check the order threshold. If free delivery already applies above a certain basket value, a free delivery code may add no extra saving.
• Compare the complete total. For guidance on thresholds and delivery conditions, see our guide to free delivery codes in the UK.

When comparing sale prices and voucher codes

• Test the code against the reduced price. A voucher may exclude sale items, or it may apply only to the original price in the retailer’s wording rather than the current checkout price.
• Check whether another offer replaces the code. Retailers often limit customers to one promotional code per order. A sale price may therefore be the better option even when a code appears on the product page.
• Consider timing. If you do not need the item immediately, review relevant sale periods and seasonal promotions without assuming that a future discount is guaranteed. Our UK sale dates and voucher calendar can help with planning.

When comparing cashback, loyalty and targeted offers

• Separate immediate and later value. An instant voucher reduces the checkout total, while cashback or loyalty rewards may be credited later and may have separate redemption conditions.
• Check whether offers can be combined. Do not assume that a voucher code, cashback offer and loyalty reward will all track together. Review the retailer and reward-provider terms before activating an offer.
• Confirm eligibility. Student, NHS and key worker discounts may require verification and can have exclusions. More guidance is available in our guide to student, NHS and key worker discounts.

What to double-check before checkout

Use this short terms checklist for every code you are considering:

1. Expiry: Is the code valid at the exact time you plan to place the order? If only a date is shown, check whether the offer ends at the start or end of that day.
2. Minimum spend: Does your eligible product total meet the threshold after exclusions and other discounts?
3. Maximum discount: Is the advertised percentage limited to a fixed amount?
4. Excluded products: Are sale items, premium brands, new releases, gift cards or marketplace products excluded?
5. Delivery: Does the code reduce postage, and does it cover the delivery service you selected?
6. New-customer rules: Is the offer limited to a first order, a new account, a particular email address or a specified payment method?
7. One-use limits: Can the code be used once per customer, household or account?
8. Stacking: Can it be combined with another code, a sale price, cashback or loyalty points?
9. Returns: Could returning part of the order remove the discount or cause the remaining basket to fall below the minimum spend?

At checkout, confirm that the code has been accepted and that the saving appears in the order summary before paying. Save a screenshot or note of the terms if the offer is important, particularly when the discount is linked to a time-limited campaign.

Common mistakes when comparing voucher codes

Choosing the largest headline percentage

A headline percentage does not show the final saving if there is a cap, an excluded product or a high minimum spend. Calculate the discount on the eligible portion of the basket instead.

Ignoring delivery charges

A product discount can be offset by delivery, especially on a small order. Always compare the delivered total rather than the product subtotal alone.

Adding unnecessary items to unlock a code

Reaching a threshold is only worthwhile if the extra item is useful and the total saving exceeds the additional cost. Otherwise, the code can encourage overspending rather than reducing it.

Assuming codes stack

Many checkout systems accept only one code, and some retailers may exclude orders using other promotions. Test combinations only where the terms allow it. See our guide to stacking vouchers, cashback and loyalty rewards for a structured way to check.

Continuing with a failed code without checking the reason

A voucher code not working may be expired, mistyped, restricted to certain products or limited to eligible customers. Check the message shown at checkout and review the retailer’s terms rather than repeatedly trying random codes. Our voucher code troubleshooting guide covers the main checks.

When to revisit this checklist

Return to this checklist whenever you have two or more offers to compare, especially before a large purchase, a seasonal sale or an order with delivery charges. Retailer terms can change when a promotion is extended, replaced or restricted, so an old description should not be treated as proof that a code still works.

For editorial use, voucher pages should be checked before major seasonal planning periods and reviewed at least twice a year. Refresh examples when minimum spends, discount caps, eligible brands, delivery rules or expiry wording changes. Shoppers should repeat the calculation whenever the basket changes, because adding or removing one product can alter eligibility.

Action plan: list each code, calculate its saving on your eligible basket, add delivery, check the terms, apply the strongest valid option and confirm the final total at checkout. The best voucher code is the one that produces the lowest genuine cost for the order you intended to place—not necessarily the one with the most impressive headline.