A purchase worth just over £135 can cross an important UK customs threshold. For goods sent to Great Britain, non-excise items worth £135 or less normally attract no Customs Duty, while goods above that value may do so. Import VAT can also include postage, insurance and any duty owed—not merely the shop price. That can turn an apparent overseas bargain into an uncomfortable bill. GOV.UK explains the current thresholds and tax base.

Duty calculator apps help you estimate these charges before buying. For UK shoppers, the most useful options are browser-based tools: Wise provides a quick UK estimate, SimplyDuty supports international comparisons, and the official UK Trade Tariff provides the most authoritative rate check.

How duty calculator apps work

An import duty calculator combines information about your purchase with customs and tax rules. Depending on the tool, you may need to enter:

  • The country where the goods originate
  • The destination country
  • The price of the goods
  • Postage, packaging and insurance
  • The product description or commodity code
  • Whether the parcel is a gift, an excise product or an ordinary purchase

The commodity code matters because different products can have different duty rates. Materials, intended use, production method and packaging may all affect classification, according to the UK Trade Tariff guidance.

For a straightforward percentage-based calculation, the process broadly follows this pattern:

  1. Establish the customs value.
  2. Apply the relevant Customs Duty rate.
  3. Calculate import VAT on the value of the goods, postage, packaging, insurance and any duty.
  4. Add any courier clearance, handling or delivery charge.

This is only a budgeting estimate. Some products use duties based on weight or quantity, while trade agreements, rules of origin, quotas and excise duties can change the result.

Understand the £135 rule before calculating

For an ordinary purchase sent to Great Britain:

  • Goods worth £135 or less: The overseas seller should normally include UK VAT at checkout, provided the goods are not excise goods.
  • Goods worth more than £135: Import VAT is normally collected by the delivery company before delivery or collection. Customs Duty may also apply.
  • Genuine gifts: Import VAT relief generally applies only when the gift is worth £39 or less. A purchase sent directly to somebody as a present is not treated as a customs gift.
  • Alcohol and tobacco: Excise Duty can apply regardless of value.

These rules come from HMRC’s guidance for goods sent from abroad and its separate guidance on imported gifts.

Northern Ireland has additional rules. In particular, duty treatment can depend on whether goods are considered “at risk” of entering the EU. A general UK calculator may therefore be less reliable for a Northern Ireland delivery.

Wise UK Import Duty Calculator

Documented functionality: Wise offers a free, browser-based UK Import Duty Calculator. It accepts the shipment origin, goods value, shipping and insurance costs, goods type, valuation method, and either a commodity code or product description. Wise says the tool uses UK Tariff information and returns an estimated duty-free result or an estimated duty rate and amount.

Best suited to: A UK shopper making an occasional overseas purchase and wanting a quick initial estimate.

Pros

  • Specifically designed for imports into the UK
  • Free to access through a web browser
  • Accepts both product descriptions and commodity codes
  • Includes fields for shipping and insurance
  • Distinguishes gifts, excise goods and other shipments
  • Clearly labels its output as an estimate

Cons

  • It only applies to UK imports
  • Wise says it does not determine product origin or applicable rules of origin
  • It does not identify quotas or special procedures that could reduce duty
  • Its page has a strong Wise Business promotional focus
  • A courier’s separate handling charge may still be missing

Assessment: Wise is the simplest starting point for a cost-conscious UK household. However, treat its result as a planning figure rather than a guaranteed final bill. For an expensive order, confirm the selected commodity code and rate through the official tariff service.

SimplyDuty

Documented functionality: The SimplyDuty calculator estimates duty and tax for hundreds of destinations. Its site advertises five free calculations per day and offers HS-code classification and landed-cost tools. The service is therefore broader than a UK-only calculator.

Best suited to: Shoppers comparing deliveries to different countries, or anyone who regularly checks several overseas purchases.

Pros

  • Covers hundreds of international destinations
  • Estimates both import duty and tax
  • Provides a limited number of free daily calculations
  • Includes product-classification tools
  • Useful when comparing the same purchase across different destination countries

Cons

  • The service is aimed partly at commercial importers
  • The free-use and registration wording varies between pages, so check the terms shown when calculating
  • SimplyDuty’s terms say that some content relies on third-party information which may not be accurate or current
  • Its terms also state that submitted data may be used under a broad licence
  • It cannot guarantee that the estimate will match a customs assessment

Assessment: SimplyDuty is useful when international coverage matters more than UK-specific guidance. For a parcel entering England, its result should still be checked against HMRC’s current tariff and thresholds.

UK Trade Tariff

Documented functionality: The government’s UK Trade Tariff service lets you find commodity codes, check duty and VAT rates, and identify suspensions or reductions. It is an official web service rather than a conventional consumer calculator.

Best suited to: Verifying the product classification and duty rate before committing to a high-value purchase.

Pros

  • Official UK government source
  • Shows current commodity codes and tariff measures
  • Covers duty rates, VAT rates, suspensions and reductions
  • Provides information relevant to preferential rates and rules of origin
  • Free and available through a browser

Cons

  • Less beginner-friendly than a one-page calculator
  • Requires a sufficiently detailed product description
  • Does not present every shopping cost as one simple landed-cost total
  • Does not predict a particular courier’s clearance or handling fee

Assessment: This is the strongest source for confirming the tariff rate, but it requires more work. A practical approach is to obtain a quick estimate from Wise or SimplyDuty, then verify the commodity code and rate here.

Which calculator is most useful?

Your situation Most suitable tool Reason
One personal purchase delivered to England Wise Simple UK-focused estimate
Purchases going to several countries SimplyDuty Broad destination coverage
Expensive, unusual or difficult-to-classify goods UK Trade Tariff Official commodity-code and rate information
Delivery to Northern Ireland UK Trade Tariff plus HMRC guidance Additional Northern Ireland rules may apply
Alcohol or tobacco Official HMRC guidance Excise rules can exceed a basic percentage estimate

This comparison reflects documented functionality and service availability checked in August 2026. It does not represent first-hand testing.

How to produce a safer landed-cost estimate

Before relying on any customs duty calculator, collect the figures from the seller rather than guessing:

  • Confirm the full goods value for the complete consignment.
  • Include postage, packaging and insurance where the calculator requests them.
  • Ask for the product’s commodity code and detailed description.
  • Check the actual country of origin, which may differ from the seller’s location.
  • Confirm whether UK VAT or import charges are already included at checkout.
  • Allow for a possible courier handling or clearance charge.
  • Keep a small budget margin for currency conversion and classification differences.

Currency movements can also affect the final assessment. HMRC publishes customs exchange rates for converting foreign-currency values into sterling, and those rates may differ from the card or marketplace rate you saw when ordering. HMRC explains how customs exchange rates are applied.

Goods from a country with a UK trade agreement may qualify for reduced or zero duty, but only when the product meets the relevant rules of origin and the necessary proof is available. The seller’s location alone does not establish origin. HMRC’s preferential-duty guidance explains these conditions.

Common calculator mistakes

Even a well-designed import VAT calculator can produce a misleading figure when the input is wrong. Common problems include:

  • Selecting a broad product category instead of the correct commodity code
  • Leaving shipping or insurance out of the customs value
  • Assuming every item from the EU is automatically duty-free
  • Treating a shop purchase as a customs gift
  • Adding VAT again when the seller has already collected it
  • Forgetting excise duty on alcohol or tobacco
  • Assuming the estimate includes the courier’s own fee

The safest comparison is the total amount leaving your household budget: purchase price, delivery, Customs Duty, import VAT and any handling charge.

Conclusion

Duty calculator apps can expose the real cost of an overseas order before it reaches your door. Wise offers the clearest UK-focused estimate, SimplyDuty is more useful across multiple countries, and the UK Trade Tariff is the authoritative final check. None can guarantee the courier’s bill, but accurate product, origin and shipping details make surprise import fees far less likely.

References