The Cost of Changing Suppliers: Why a Lower FOB Is Not the Whole Price
A new quotation arrives £0.70 per unit below the incumbent FOB on a hoodie that sells 12,000 units a season, and the costing review wants to know whether that saving survives contact with reality. The honest answer depends on the cost of changing suppliers, which sits outside the quotation: development, onboarding, failed samples, extra inspection, different freight, late-delivery exposure and the hours your own team spends chasing and correcting.
Supplier switching cost is the total of one-off and recurring costs you carry only because the programme moved, measured against what you would have spent with the incumbent. FOB is a price at the port of loading, so it ignores most of this. Landed cost is closer, because it adds freight, insurance, duty, inland costs and fees, but even landed cost leaves out the transition work and the risk of missing the selling window.
Every figure above comes from a hypothetical model built later in this guide, not from market data. The point is the method: list every cost the switch creates, estimate each one with stated assumptions, and compare incumbent and challenger over a full season rather than per unit at the port.
What Is Included in the Cost of Changing Suppliers?
The cost of changing suppliers has two layers. One-off costs happen once, when you qualify and develop with a new factory. Recurring costs continue each season until the new supplier has proved itself, and they often shrink with a good track record. Separating the two lets you see whether a saving is permanent or only starts to pay back after the transition is complete.
Components of supplier switching cost
| Cost component | One-off or recurring | How to estimate it | Where it appears |
|---|---|---|---|
| Re-development and sampling | One-off | Number of extra sample rounds multiplied by sample, courier and test cost | Development budget |
| Supplier onboarding and compliance review | One-off | Hours for document review, audit acceptance and system set-up at your loaded rate, plus any visit or third-party fees | Sourcing or compliance budget |
| Failed samples and retests | One-off, then falling | Expected failures multiplied by the cost of each repeat round | Development budget |
| Extra inspection | Recurring until trusted | Added inspection visits multiplied by the fee per visit | Quality budget |
| Freight, insurance, duty and inland | Recurring | Landed cost build-up from the new origin and port; confirm duty with the UK Trade Tariff or a customs broker | Landed cost |
| Late-delivery and markdown exposure | Recurring, probability-weighted | Units at risk multiplied by assumed cost per late unit | Gross profit |
| Internal chasing and correction time | Recurring until stable | Hours per week multiplied by weeks in programme multiplied by loaded hourly rate | Overhead, often unrecorded |
A structure for the cost of changing suppliers. Which budget carries each line varies by company, so agree with finance where each cost is booked.
The right-hand column matters politically. Development and compliance costs often sit in a different budget from product cost, so a sourcing saving can be reported in one place while its price is paid in another. A switching model that shows both on one page stops that happening.
Step 1: Estimate Development and Onboarding Cost
Start with what has to be rebuilt. The incumbent already holds your patterns, graded size set, approved fabric and wash standards, trim library and test history. A new supplier needs most of this recreated or re-validated, so assume the garment returns to development even if the design is unchanged. Fit approval, fabric and colour approval, wash or decoration approval and lab testing each need their own sign-off, and each can need more than one round.
Onboarding is separate work. It covers checking compliance documents and audit status, agreeing quality and inspection protocols, setting up payment terms, sharing the tech pack standard and confirming who owns approvals. For a first order, put the hours on a sheet at your loaded internal rate, and add any third-party audit or travel fees. Our vetting checklist is a useful prompt for what to verify before work begins.
In the worked example later, three development rounds are assumed at £320 each, including sample cost, courier and test fees, which gives £960. Onboarding is assumed at £1,800 in internal time and review costs. Both figures are hypothetical. Replace them with your own sample invoices and timesheets.
Step 2: Include Failed Samples, Inspection and Freight
Failed samples are the line most often left out. A new supplier will not match the incumbent on first-time-right, and each failed fit sample or repeated lab test carries a sample charge, courier, a retest fee and, more expensively, calendar days. Count failures as expected cost, not as bad luck. A defensible method is to use the incumbent first-time-right history as a floor and assume the new supplier needs at least one more round per critical approval.
Inspection works the same way. An established supplier may need one final inspection per order, while a new supplier usually justifies an inline or mid-production check as well until a track record exists. Use your AQL inspection plan to define what each visit covers, and price each added visit at the fee you actually pay.
Freight and landed cost differ by origin, port, consolidation and mode. Build a landed cost for each supplier from FOB plus freight, insurance, duty, import VAT handling where it affects cash flow, inland transport and fees. Check duty with the UK Trade Tariff or a customs broker and confirm Incoterms rules with the ICC publication rather than relying on assumption. Our guide to what FOB price includes shows where the boundary lies.
How predictable is each cost before you switch?
1 dot = low, 5 dots = high
| Predictability before switching | Size of swing if wrong | |
|---|---|---|
| Sample and development cost | ●●●●● | ●●●●● |
| Onboarding and compliance review | ●●●●● | ●●●●● |
| Failed samples and retests | ●●●●● | ●●●●● |
| Extra inspection | ●●●●● | ●●●●● |
| Freight and landed cost differences | ●●●●● | ●●●●● |
| Late delivery and markdown exposure | ●●●●● | ●●●●● |
| Internal chasing and correction time | ●●●●● | ●●●●● |
Indicative 1-5 ratings to show where to spend estimating effort, not measured data. Your own history will differ.
The pattern is useful. The costs you can quote with confidence, such as samples and inspections, are rarely the ones that decide the case. Late delivery and internal time are the hardest to predict and the most damaging when wrong, so they deserve the most careful assumptions.
Step 3: Model Late-Delivery and Markdown Exposure
Late-delivery exposure is the expected cost of units arriving after the planned selling window. It is a probability-weighted figure, not a prediction of failure: late units equal units ordered multiplied by the share expected to arrive late, and exposure equals late units multiplied by the cost per late unit. The cost per late unit combines lost full-price sales, the markdown needed to clear the units later and any expedite freight or air cost used to recover.
For the incumbent, use its actual record, measured as the share of order lines or units delivered after the agreed date. For a new supplier there is no record, so use a stated assumption that is higher than the incumbent for the first season and falls only if on-time performance is demonstrated. This is a risk-reduction approach, not a forecast. Delay on a seasonal hoodie matters more at the start of a cold-weather window than the end of it, so adjust the cost per late unit by when the delivery is due. Our guide to preventing garment production delays covers the milestones that create late shipments.
Keep this line visible even when it is uncertain. Excluding it sets the cost of lateness at zero, which is the least likely assumption of all. A range, such as best case and cautious case, is better than a single figure.
Step 4: Measure Internal Chasing and Correction Time
Internal time is the cost of changing suppliers that nobody invoices. Buying, technical and quality teams spend hours on status requests, repeated clarifications, re-sent files, re-checking measurements and correcting purchase orders. With an established supplier much of that effort has become routine, so it is easy to undervalue when comparing a challenger that needs more attention.
Measure it rather than guess. Ask the team to log hours spent on the incumbent over a representative month, in categories such as chasing updates, clarifying specification and fixing errors, then apply the same categories to the new programme. Multiply hours per week by weeks in the programme and by a loaded hourly rate that includes salary and overheads. Some finance teams book this below gross profit; the model should still show it so the decision is made on the full picture.
The same log gives you a chase rate, meaning the number of supplier follow-ups needed per milestone. A falling chase rate is one of the earliest signs that a new supplier is stabilising, and our guide on how to stop chasing suppliers after the PO explains how to set up the reporting that reduces it.
How to Build a Supplier Switching Cost Model in Five Steps
A switching model is a short spreadsheet, not a project. The sequence below keeps it consistent between styles, so two suppliers or two seasons can be compared on the same basis.
Five steps to a switching cost model
- 1Fix the comparison basisSame style, specification, volume, delivery window and test requirements for both suppliers, so any difference is real.
- 2Build total landed costFOB plus freight, insurance, duty, inland and fees for each supplier, from dated quotes and a broker check.
- 3Add one-off switching costsRe-development, onboarding, failed samples and retests, entered with explicit assumptions.
- 4Add recurring risk and timeExtra inspection, late-delivery exposure and internal hours for the first season and a stabilised second season.
- 5Find break-evenDivide fixed switching costs by the net saving per unit, then test the result against optimistic and cautious cases.
A generic method. Replace every input with your own dated quotations, invoices and timesheets.
For the first step, a like-for-like basis is the same discipline used when you compare supplier quotations. Without it, any difference you find may be a specification gap, not a supplier difference.
Worked Illustration: Incumbent vs New Supplier Over a Full Season
The following example is hypothetical and exists to show the arithmetic. It does not represent any real supplier, cost structure or result. We compare one hoodie programme of 12,000 units across a season with an incumbent and a new supplier whose FOB is £0.70 lower. Seasons two and three are shown on the assumption that the new supplier stabilises.
Illustrative assumptions (all hypothetical)
| Input | Incumbent | New supplier, season 1 | New supplier, season 2 |
|---|---|---|---|
| Units for the season | 12,000 | 12,000 | 12,000 |
| Selling price excluding VAT per unit | £28.00 | £28.00 | £28.00 |
| FOB per unit | £8.00 | £7.30 | £7.30 |
| Freight, insurance, duty and inland per unit | £1.80 | £1.90 | £1.90 |
| Share of units delivered late | 5 per cent (600 units) | 12 per cent (1,440 units) | 7 per cent (840 units) |
| Cost per late unit (markdown, lost sales, expedite) | £4.00 | £4.00 | £4.00 |
| Inspection visits at £300 each | 1 | 3 | 2 |
| Internal hours chasing and correcting, over 20 weeks | 80 (4 per week) | 200 (10 per week) | 100 (5 per week) |
| Internal loaded rate per hour | £35 | £35 | £35 |
| One-off: 3 development rounds at £320 | None | £960 | None |
| One-off: failed samples and retests (2 fit samples at £320, 2 retests at £280) | None | £1,200 | None |
| One-off: onboarding and compliance review | None | £1,800 | None |
Every input is an assumption for illustration. Replace with your own dated figures; duty and freight must come from the UK Trade Tariff, a customs broker and your forwarder.
The first three rows set the commercial frame. The late-delivery and internal-hours rows carry the main judgement, because they are the least predictable costs and the ones a plain FOB comparison leaves out. With the assumptions fixed, the season model below adds each line and shows total cost, gross profit and margin.
Illustrative season model: incumbent vs new supplier
| Line | Incumbent | New, season 1 | New, season 2 |
|---|---|---|---|
| Landed cost (units multiplied by landed cost per unit) | £117,600 (at £9.80) | £110,400 (at £9.20) | £110,400 (at £9.20) |
| Late-delivery cost | £2,400 | £5,760 | £3,360 |
| Inspection | £300 | £900 | £600 |
| Internal chasing and correction time | £2,800 | £7,000 | £3,500 |
| One-off development, failed samples and onboarding | £0 | £3,960 | £0 |
| Total season cost | £123,100 | £128,020 | £117,860 |
| Total cost per unit sold | £10.26 | £10.67 | £9.82 |
| Sales at £28.00 ex VAT | £336,000 | £336,000 | £336,000 |
| Gross profit after switching costs | £212,900 | £207,980 | £218,140 |
| Gross margin | 63.4 per cent | 61.9 per cent | 64.9 per cent |
| Result vs incumbent | – | £4,920 worse | £5,240 better |
Illustrative arithmetic only. Gross margin is (selling price excluding VAT minus cost) divided by selling price excluding VAT, here applied to the whole season.
On these assumptions the cheaper supplier loses £4,920 in the first season despite a £0.70 lower FOB, and gains £5,240 in a second season in which late deliveries and internal hours fall. Cumulatively the switch is £320 ahead only part-way through season two. The next chart shows where the FOB saving of £8,400 goes in season one.
Where the illustrative £8,400 FOB saving goes in season one
£ per season, hypothetical
Illustrative values from the worked example. The five cost bars total £13,320; less the £8,400 saving, the net season-one result is minus £4,920.
Internal time and one-off costs together account for most of the added cost, which is typical of a switch where the product itself is well specified. The composition below groups the same £13,320 into four parts.
Illustrative mix of the £13,320 in season-one switching costs
Share of added cost
Rounded shares of the worked example above, which sum to 100. They are not industry proportions.
Break-Even: When Does the Cost of Changing Suppliers Pay Back?
Break-even for a supplier switch is the volume or time at which cumulative savings equal cumulative switching costs. For one season, the formula is fixed switching costs divided by the net saving per unit. In the example, fixed switching costs in season one are £8,760: £3,960 of one-off costs, £600 of extra inspection and £4,200 of extra internal time. The net saving per unit is the £0.60 landed saving less £0.28 of extra expected late cost per unit, which is £0.32.
Dividing £8,760 by £0.32 gives 27,375 units, more than twice the season volume. A single-season payback is therefore out of reach unless the quote is lower, the volume larger or the transition cheaper. From season two the fixed cost drops to £1,000 and the net saving per unit rises to £0.52, so break-even falls to about 1,923 units, which is why cumulative results turn positive in the second season.
Illustrative season-one net result by late-delivery share and volume
| Late share, new supplier | 6,000 units | 12,000 units | 24,000 units |
|---|---|---|---|
| 5 per cent (same as incumbent) | –£5,160 | –£1,560 | +£5,640 |
| 8 per cent | –£5,880 | –£3,000 | +£2,760 |
| 12 per cent (worked example) | –£6,840 | –£4,920 | –£1,080 |
| 16 per cent | –£7,800 | –£6,840 | –£4,920 |
Illustrative: net result of new supplier versus incumbent in season one, with fixed switching costs unchanged and all other assumptions as in the worked example. Positive means the switch wins.
Two readings follow. Even with no extra lateness, a 12,000-unit season does not recover the transition in season one. And with 24,000 units, a switch only wins if lateness stays close to the incumbent. To make season one break-even at 12,000 units with the example lateness, the new FOB would have to be about £1.11 below the incumbent instead of £0.70.
If the break-even point lies beyond the volume you can credibly commit, treat the first order as a paid trial, not as a saving. Record the expected net cost of that trial in the sourcing plan.
KPIs: Total Landed Cost, Delays and Gross Profit
Three measures carry this decision. Define each before the comparison starts, because definitions vary between companies and a switch that looks good on one definition may not on another.
KPIs for judging a supplier switch
| KPI | Definition and formula | What it tells you | Watch for |
|---|---|---|---|
| Total landed cost | FOB plus freight, insurance, duty, import VAT handling where it affects cash flow, inland costs and fees. A switching-adjusted version adds one-off and recurring switching costs, then divides by units sold | Whether the saving survives the full cost of getting goods to your warehouse | Quotes on different Incoterms, duty assumptions out of date, switching costs left out |
| Delays | Share of order lines or units delivered after the agreed date, plus days late. State whether you measure at the line or unit level; OTIF combines on time and in full | How much selling window is lost, and the basis for late-delivery cost | Measuring against a date the supplier never agreed, hiding partial shipments |
| Gross profit | Sales excluding VAT minus cost of goods and attributable switching costs. Gross margin equals gross profit divided by sales excluding VAT; markup equals profit divided by cost | The result after markdown and switching are charged to the programme | Confusing margin with markup, booking internal time below the line without disclosing it |
Definitions vary by retailer and finance team. Agree them in writing before comparing suppliers.
In the worked example, the switching-adjusted cost per unit sold is £10.26 for the incumbent, £10.67 for the new supplier in season one and £9.82 in season two. Late units fall from 1,440 to 840 between the seasons, and gross profit after switching costs moves from £207,980 to £218,140. Track all three each season, using the supplier scorecard to hold the on-time and quality records.
Decision: Switch, Stage or Stay?
The model gives three options. Switch fully when break-even is within a volume and time you can credibly commit and the assumptions have evidence behind them. Stage the move when the case is positive only if reliability is proven: place a small controlled order first, as described in our guide to testing a new hoodie supplier without risking the core programme, and keep the incumbent on core volume. Stay when the break-even is beyond any realistic commitment, or when the saving relies on a lateness assumption you cannot support.
Evidence that should change the decision
- Dated quotations from both suppliers on the same Incoterm, specification and test requirements
- Incumbent delivery and first-time-right history for the last two seasons
- A written lateness assumption for the new supplier, with the evidence behind it
- Sample invoices and timesheets behind every one-off switching cost
- Landed cost checked with the UK Trade Tariff or a customs broker, not assumed
- A named owner for the model and a date when assumptions are reviewed against actuals
Use this as a pre-approval gate. If an item cannot be filled, state the assumption openly.
Not every switch is about price. Capacity limits, a product the incumbent cannot make, or concentration risk can justify a move even when the first season costs more, and our guide to building a backup supply chain covers that case. What matters is that the cost is known and chosen, not discovered after the purchase order.
Which single assumption in your own switching model, whether the lateness share, the internal hours or the volume, would have to be wrong by the smallest amount to reverse the decision, and who has the evidence to test it?
How Ruhrose Approaches Supplier Transitions
Ruhrose is a Bangladesh-based manufacturer of hoodies, jersey, denim and woven casualwear with UK buyer support, so we are often the new supplier in this comparison and have an interest in the answer. Our practice is to sample before bulk, agree the specification and test requirements in writing, and encourage buyers to start with a controlled order rather than moving core volume. The test-and-scale model is a risk-reduction approach, not a risk-free one, and a test quantity such as 500 pieces per style and colour is a proposed starting point where it is commercially and technically feasible. It is not a guaranteed minimum. If the switching maths does not favour a move, we would rather you stay with the incumbent.