Interactive growth suite

Free Amazon calculators and unit-economics tools.

Work out your break-even ACoS, your true profit per unit and your TACoS ratio, so ad spend scales the brand instead of eating the margin. Every figure is an estimate built from the numbers you type in — nothing is stored, nothing is sent anywhere, and none of it is a reading of your account.

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01Advertising ceiling

Break-even ACoS

The highest ACoS you can run before an ad-driven sale starts costing you money. Most break-even calculators forget the Amazon referral fee and overstate your ceiling by the whole referral rate — this one charges it.

Selling price (£)

Cost of goods (£)

FBA fulfilment fee (£)

Amazon referral fee (%)

Returns allowance (%)

The ACoS you are running now (%)

Referral fee is 15% in most Amazon categories but runs from 8% upwards — check your own category rather than trusting the default. Returns allowance is the share of revenue you write off to refunds; leave it at zero if you would rather not guess.

Your break-even ACoS

42.2%

Contribution per unit, before advertising £10.55

Headroom against the ACoS you run now +20.2pp

Highly profitable ad-driven sales.

How this is worked out

Referral fee = selling price times referral rate, divided by 100. Returns allowance is charged the same way.
Contribution per unit = selling price minus cost of goods, minus FBA fee, minus referral fee, minus returns allowance.
Break-even ACoS = contribution per unit divided by selling price, times 100, never less than zero. Spend all of your contribution on advertising and the sale makes you nothing.
Headroom = break-even ACoS minus the ACoS you run now, in percentage points.

These figures recalculate with JavaScript switched on. Without it nothing you type changes them: what is shown is the worked example at the default inputs above, not an answer about your product. The four lines above are the whole model, so you can run your own numbers on paper in a minute.

Not counted: storage and long-term storage fees, inbound freight, VAT, and any per-unit overhead. Each of those routinely moves break-even by two to five percentage points, so treat this as your ceiling on a good day.

02Unit economics

FBA unit profit and ROI

What one unit actually earns once Amazon has taken its cut, and what that is as a return on the cash you have tied up in it.

Selling price (£)

Cost of goods (£)

Inbound freight per unit (£)

Amazon referral fee (%)

Pick and pack fee (£)

Storage per unit (£)

Advertising cost per unit sold (£)

Storage and advertising start at zero. Leave them there and the profit figure is contribution before advertising, which is what most FBA calculators quietly report as "net profit". Fill them in and it becomes a number you can bank.

Profit per unit

£11.50

Total Amazon fees per unit £9.00

Return on the cash tied up in each unit 121%

Net margin on the selling price 38.3%

How this is worked out

Total fees = selling price times referral rate divided by 100, plus pick and pack, plus storage per unit.
Landed cost = cost of goods plus inbound freight. That is the cash you have tied up in the unit before you sell it.
Profit per unit = selling price minus landed cost, minus total fees, minus advertising per unit. It is allowed to go negative, because sometimes it is.
Return on cash = profit divided by landed cost, times 100. Net margin = profit divided by selling price, times 100.

Not counted: long-term storage surcharges, removal and disposal fees, returns processing, and VAT. If you sell across several marketplaces the referral rate and the fulfilment fee change per marketplace, so run it once per market.

03Whole-account view

TACoS health ratio

ACoS only sees the sales advertising caused. TACoS measures total ad spend against everything the store sold, which is the number that tells you whether advertising is buying organic rank or renting it.

Total monthly ad spend (£)

Total monthly revenue, advertising and organic (£)

Use total ad spend across every campaign type, including Sponsored Brands and Sponsored Display, against total marketplace revenue for the same month.

Your TACoS ratio

16.7%

Aggressive launch or growth, 15% to 22%.

These bands are Ecom Enable benchmarks for private-label brands, not a universal standard. TACoS health depends on your gross margin: the same ratio can be comfortable for a high-margin brand and ruinous for a thin-margin one. Run the break-even calculator above first, then read this against it.

How this is worked out

TACoS = total monthly ad spend divided by total monthly revenue, times 100.
The band is read from the rounded figure you can see, not from an unrounded one behind it, so the label can never contradict the number beside it.
A falling TACoS at flat spend means organic is carrying more of the load. A rising TACoS at flat spend means it is carrying less.

This ratio recalculates with JavaScript switched on. Without it nothing you type changes it: what is shown is the worked example at the default inputs above, not an answer about your account. The three lines above are the whole model, so you can run your own numbers on paper in a minute.

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