Writing your product warranty: what to promise, what to exclude, and example wording

Three sentences decide most warranty outcomes: what's covered, for how long, and what you'll do when it fails. Get those three precise and the rest of the document is scaffolding. Leave them vague and you'll spend a month disputing a $24 bike light with a customer who read your silence as an open-ended promise. This article lays out the parts a warranty needs, the exclusions that earn their place, the cost math for choosing a duration, and wording blocks you can adapt — general commercial drafting practice, not legal advice, and worth a counsel review before you publish.

Writing the document is half the job. What happens when a claim actually arrives — how it's routed against ordinary returns, inspected, and recorded — is the other half, covered in routing warranty claims against returns.

The three parts every warranty needs

• Scope. Which products, which defects, and whose purchases the promise covers. Narrow and specific beats broad and fuzzy: "defects in materials and workmanship" is a promise you can evaluate; "any problems" is a dispute generator.
• Duration. From what date, measured how. Delivery date per the order confirmation is the cleanest anchor, and it should be stated, not implied.
• Remedy. What you actually do — replace, repair, or refund, and in what order. The remedy is the sentence customers remember.

A fourth element is usually missing: the claim process — where to write, what to include, and how fast you'll respond. A promise without an intake route produces exactly the mis-routed requests that make warranty data useless.

Full vs limited warranty: what the labels commit you to

In the US, federal warranty law requires that written warranty terms be available to buyers before sale, and it reserves the label "full" for warranties meeting minimum standards — free repair or replacement within a reasonable time, without unreasonable conditions (FTC, A Business Guide to Federal Warranty Law, accessed November 2026). Anything short of that is a "limited" warranty, which is perfectly legitimate as long as it is labeled and disclosed.

For a catalog of 100–5,000 SKUs, a clearly written limited warranty — twelve months, replace-first remedy, explicit exclusions — is the pragmatic middle. Also worth knowing: implied warranties, such as merchantability, exist by default in much of the US and can be limited in writing in many states, but the rules vary by jurisdiction, so treat any disclaimer sentence as something for counsel to review rather than a template to copy.

Exclusions that earn their place

• Normal wear. Padding compresses, finishes scuff, straps fray with use. Saying so explicitly is what stops a two-year-old product from becoming a claim.
• Misuse and accidents. Drops, crashes, chewed corners — real-world damage the product was never rated to survive.
• Unauthorized modification or repair. A third-party fix that preceded the failure voids coverage; otherwise you are warranting someone else's work.
• Consumables. Batteries, straps, filters, seals — parts designed to be replaced. Name them individually; "consumables" alone invites arguments about what counts.
• Environment beyond rating. Water past the IP rating, months of UV exposure, road salt, freezer temperatures — use the product's stated limits as the boundary.
• Transferred ownership. Coverage follows the original purchaser unless you explicitly say otherwise; second-hand units carry a history you can't see.
• Cosmetic issues that don't affect function. A scuff that still performs is not a defect, and saying so prevents the most subjective claims.
• Loss or theft. A warranty covers how the product performs, not whether it stays in your possession.

One caution: exclusions should trim the promise, not swallow it. An exclusion list longer than the coverage reads as fine print, invites disputes, and can collide with the disclosure rules above. Separately, safety-adjacent defects are not only warranty events — a component that fails in a way that could injure someone can carry reporting obligations of its own (U.S. Consumer Product Safety Commission guidance, accessed November 2026); route those out of the ordinary claims queue immediately.

Choosing the duration: the cost math

Duration is a cost decision, and it has arithmetic. Illustrative setup: LIGHT-TR-02, a rechargeable bike light with a $9.20 unit cost and an estimated $4.50 to ship a replacement. From your defect ledger — thin as it may be — assume 1.5% of units fail within 12 months and 4% within 24. Set those rates from your own data; the numbers below show the method, not a benchmark.

• 12-month coverage: 0.015 × ($9.20 + $4.50) = 0.015 × $13.70 = $0.21 per unit sold (illustrative)
• 24-month coverage: 0.04 × $13.70 = $0.55 per unit sold (illustrative)

The difference is $0.34 a unit — under 1.5% of a $24 retail price. On a reliable product, doubling the duration is cheap, which is why long warranties on well-made goods are rational. The danger isn't the average; it's the bad batch. One weak component lot pushing the 12-month failure rate to 15% turns the same math into 0.15 × $13.70 = $2.06 per unit — 8.6% of retail, gone, across everything sold in that window. Two mitigations: prefer a replace-first remedy, which bounds the cost per claim at one unit plus shipping; and set the duration from your own ledger even when the data is thin — a duration chosen without any defect data is a guess wearing a number.

The remedy ladder

Replace-first is usually right at small scale: the cost per claim is bounded, the customer is made whole in days, and every claim returns a failed unit you can inspect — which is also the raw material for the defect ledger that sets your duration.

Example wording blocks you can adapt

Fill the brackets, delete what doesn't apply, and keep the numbers consistent with your return policy:

Scope. "This warranty covers defects in materials and workmanship in [product name] purchased new from [store name] or an authorized retailer."

Duration. "Coverage lasts 12 months from the delivery date shown on your order confirmation."

Remedy. "If the product fails due to a covered defect, we will replace it at no charge. If a replacement is unavailable, we will repair it or refund the purchase price."

Exclusions. "This warranty does not cover damage from misuse, accidents, unauthorized modifications, normal wear, consumable parts such as batteries and straps, or use beyond the product's stated limits."

Claim process. "To make a claim, email [support address] with your order number and a photo or short video of the issue. We reply within 2 business days; approved claims ship a replacement within 5 business days."

Two drafting habits: write the numbers in terms a customer can quote back at you, and publish the document somewhere findable — Shopify supports custom policy pages you can link from your footer and product descriptions (Shopify Help Center, accessed November 2026). A warranty nobody can find protects nobody.

Keep it consistent with your return window

Customers read the return policy and the warranty as one system, so the ladder should be clean: the return window handles remorse, the warranty starts where the window ends, and neither contradicts the other. A 30-day return window inside a 12-month warranty is coherent; a "no returns after 7 days" policy beside a 24-month warranty invites the exact dispute the warranty was meant to prevent. How to set the window itself — length, fees, and what a longer window costs you — is covered in choosing a return window length.

Common questions

What's the difference between a warranty and a return policy? A return policy governs the short window after purchase when a customer can send back an unwanted product for a refund; a warranty is a longer promise that you will repair or replace a product that fails through a covered defect. The return policy handles changed minds; the warranty handles failures.

What makes a warranty "limited"? Anything less than the full-warranty standard — duration caps, exclusions, customer-paid shipping, or a remedy limited to replacement rather than refund. There is nothing wrong with limited; most small-catalog warranties are. The obligation is disclosure — label it limited and disclose the terms before the sale (FTC, accessed November 2026).

Can I exclude implied warranties? In many US states, a written, conspicuous disclaimer can limit implied warranties like merchantability, but wording and enforceability rules vary by state, and some jurisdictions restrict disclaimers more than others. Check current FTC guidance and local law, and have counsel review the exact sentence before relying on it.

How long should a product warranty last? Set it from defect economics, not generosity: expected cost = failure rate within the period × (unit cost + replacement shipping). In the illustrative example above, 12-month coverage costs about $0.21 per unit sold versus $0.55 for 24 months. Pick the longest duration whose per-unit cost stays trivial against your retail price.

Do warranties transfer to a second owner? Only if your document says so. The default in most merchant warranties is coverage for the original purchaser, which is why "purchased new from you or an authorized retailer" appears in the scope sentence. If you want transferable coverage — a genuine selling point for durable goods — state it explicitly.

Next step

Draft your three-sentence core today — scope, duration, remedy — using the blocks above, then publish it as a policy page and link it from your footer. If the document exists but claims have no intake route yet, set up the routing described in routing warranty claims against returns, and align the return window that precedes the warranty with the return window guide.