UK postage research belongs in a dated operating record, not permanent product copy. Measure the closed and protected parcel, choose the exact service and purchasing channel, then verify dimensions, weight, price and terms from the carrier’s official source. A label such as “standard shipping” is too vague for product design or margin planning.
Royal Mail format reference checked 11 July 2026
The following external dimensions were recorded from Royal Mail official material on 11 July 2026. They are a design reference, not a guarantee of a future service. Recheck before freezing geometry, publishing a delivery option or buying postage.
| Format and service context | Maximum external dimensions recorded | Maximum weight recorded |
|---|---|---|
| Large Letter — standard 1st or 2nd Class context | 35.3 × 25 × 2.5 cm | 750 g |
| Large Letter — Royal Mail Tracked context | 35.3 × 25 × 2.5 cm | 1 kg |
| Small Parcel | 45 × 35 × 16 cm | 2 kg |
| Medium Parcel | 61 × 46 × 46 cm | 20 kg |
The Large Letter weight distinction matters. Do not combine the 750 g limit associated with standard 1st/2nd Class formats and the 1 kg Tracked Large Letter context into one universal category. The service offered to a seller’s account may also depend on channel, destination and current terms.
No postage prices are reproduced here. Rates can change, differ between online, Post Office counter and business-account purchasing, and depend on weight step and service features. Use the official current table at the time of the decision.
Build a carrier evidence row
For every service being considered, record:
- carrier and exact service name;
- domestic or international destination scope;
- purchasing channel and account type;
- maximum length, width, depth and weight;
- applicable weight step for the measured parcel;
- tracking, signature, delivery aim and compensation terms;
- exclusions, surcharges or acceptance conditions relevant to the product;
- official source URL, published/effective date if shown and checked date;
- price including any applicable tax treatment as presented for that channel;
- person responsible for checking it and the next review date.
Store this volatile information outside the CNC drawing. The drawing can reference a packed-size target and evidence record ID. That prevents a carrier price from masquerading as an enduring design fact.
Leave margin below a boundary
A product designed to equal the maximum format dimensions before packing does not fit. Protection, seams, closure tape and bulges add external size. Sheet material and finishes vary. Manual packing varies. Measurement equipment also has limits.
Choose an internal target with enough clearance for the real process, then sample multiple finished parcels. Do not compress a flexible mailer during measurement to force it into a band. If one dimension sits close to a threshold, investigate whether the product function permits a change or whether the next service is the honest plan.
Example threshold decision
A long personalised key rack can be thinner than a target parcel depth while bare, then exceed it once mounting hardware and corner protection create local bulges. Measure the first closed pack at its thickest points rather than relying on average thickness. Current postage prices and service eligibility still need checking for the actual parcel.
The seller considers removing the hardware, but customer convenience and the risk of incorrect substitutes matter. A recessed hardware pocket might help, yet it changes wall clearance and requires a new prototype. The seller compares that design route with an honest parcel service using current official prices and compensation. The decision is made from total cost, buyer experience and risk—not from forcing a favoured label category.
Record standard and tracked options separately, including the checked date and purchasing channel. Base listing postage charges on your current dispatch data rather than assuming this article contains a permanent rate.
CNC and product-design handoff
Tell Wood to Spec the functional maximum product envelope and the target protected envelope. Identify dimensions open to adjustment, removable components and any joint proposed for flat packing. Provide the official-source record that motivated the constraint.
The workshop can review whether a geometric change appears machinable and quote the confirmed scope. It cannot warrant the final seller-packed dimensions, carrier acceptance, price, delivery time or compensation. The seller must assemble, finish, pack, measure and verify the completed item.
Common rate-research errors
Using 1 kg for every Large Letter service. Service context changes the recorded maximum; standard 1st/2nd Class and Tracked information must stay distinct.
Comparing an online price with a counter purchase. Label every rate with channel and account type.
Checking only dimensions. Weight step, compensation, tracking, destination and prohibited contents may change suitability.
Publishing an undated price in a guide. Link to the current official source or display a dated managed dataset with a review process.
Designing exactly to a limit. Add protection and process allowance, then measure repeated closed examples.
Optimising postage while damaging the product. Preserve buyer function and protection; compare the next service honestly.
Carrier-research checklist
- The completed parcel has been measured and weighed.
- The exact service, destination and channel are identified.
- Large Letter weight context is not merged incorrectly.
- Every size and weight fact has an official source and checked date.
- The relevant weight step is used, not only the maximum.
- Tracking, compensation and delivery aims are reviewed.
- Product exclusions and surcharges have been checked.
- Product design leaves practical clearance below any threshold.
- More than one packed example is checked where variation matters.
- Listing and costing data names who checks it and the next review date.
- Carrier acceptance is not promised by the CNC supplier.
Questions about carrier bands and rate checks
What is the current UK postage price?
It depends on carrier, service, channel, weight step, destination and date. Use Royal Mail current postage prices or the chosen carrier’s equivalent official table when buying or reviewing costs.
Are the dimensions above guaranteed to remain current?
No. They are explicitly a record checked on 11 July 2026. Reconfirm them using Royal Mail UK sending services and its current measuring guidance.
Should I reduce my product to fit Large Letter?
Only if the finished pack can fit with sensible margin and the change preserves usefulness, safety, presentation and margin. Model the alternative parcel rather than treating one band as mandatory.
Do business rates match online consumer prices?
Not necessarily. Use Royal Mail business prices and the current terms for the actual account, while keeping counter, online and contract data separate.
Use current carrier data at every review
Primary sources for this reference include current postage prices, UK sending services, weighing and measuring guidance and business prices. Carrier rules supersede this page. Review before design freeze and dispatch, and whenever the service, channel, product or pack changes.
Send the packed design with dimensions, weight, source date and the product changes you are willing to consider.