Most guides stop at that definition. This one keeps going, because the reason variable costs matter is that they decide what you actually keep on each sale. Get them wrong and a "profitable" store quietly loses money on every order.
What is a variable cost?
A variable cost is any business expense that is directly tied to your production or sales volume. When output increases, variable costs rise — when production slows, they fall.
The key trait is that the cost per unit stays roughly the same while the total moves with volume. If each shirt costs you a fixed supplier rate to make, that per-unit figure holds whether you sell ten shirts or a thousand. Your total product cost is what scales.
That is the opposite of a fixed cost, which stays put no matter how much you sell. Rent, your Shopify subscription, and a salaried employee cost the same in a slow month as in a busy one. Fixed costs must be incurred no matter what the activity level of the business may be, while variable costs are only incurred if there is some amount of activity.
For print-on-demand specifically, the cost charged by a fulfillment partner for producing and shipping each item is a textbook variable cost: it's only incurred when a real order comes in, not paid upfront. That structure means your fixed overhead stays lean — but it also means your variable cost per order is the primary profitability lever, since there is no bulk-discount floor to fall back on.
Variable costs vs. fixed costs
The split between variable and fixed is the single most useful distinction in your P&L, because it tells you what happens to your money when volume changes.
| Trait | Variable cost | Fixed cost |
|---|---|---|
| Moves with sales? | Yes, up and down | No, stays flat short-term |
| Cost per extra order | Roughly constant | Falls as you spread it wider |
| Examples | Product, shipping, card fees | Rent, salaries, software |
| Zero if you sell nothing? | Yes | No |
Fixed costs get cheaper per order the more you sell, because you spread the same lump over more units. Variable costs do not — the tenth order and the ten-thousandth order each carry the same variable load.
One caveat: some costs are really "step" costs or semi-variable costs. A second warehouse is a good example: fixed within a range, then it jumps to a new level once you outgrow the first. Treat those as fixed until the step, not as smoothly variable.
Common examples of variable costs
For a typical online or print-on-demand store, the recurring variable costs are:
- Cost of goods sold (COGS) — the blank product plus the print or embroidery service. COGS is one of the biggest costs in POD, covering the blank product plus the printing or embroidery service — and it is variable because pricing depends on the supplier, fulfillment location, and discounts from premium plans. See our Printful cost full breakdown and Printful pricing breakdown for a real-world look at what COGS looks like on a POD order.
- Fulfillment fees — variable costs include shipping expenses, fulfillment fees, and costs associated with making each product. On Printful, for instance, you only pay when a customer places an order in your store — once they place an order and pay your set retail price, Printful charges you for fulfillment and shipping costs.
- Shipping and carrier fees — what it costs to physically move each order. Carrier and fulfillment shipping charges rise with every order you send and fall to zero when you send none, which is the textbook definition of a variable cost. Any flat-rate warehouse rent tied to shipping, however, is fixed. See our Printful free shipping breakdown for how free-shipping thresholds change the economics.
- Payment processing fees — a percentage plus a flat fee on every transaction. The standard online card rate is 2.9% + 30¢ per transaction on Stripe, and most processors sit near that. Note that only the percentage-of-sales portion of card fees is truly variable — any flat monthly fee is fixed.
- Pick, pack, and per-order labor — variable cost per order includes picking cost, packing cost, packaging materials, average carrier fee, handling fees, and an average return provision. Piece-rate or per-shipment labor scales directly with volume and is one of the most purely variable labor costs a business can track.
- Sales commissions — if you pay affiliates or sales staff a percentage of each sale, that commission is entirely variable.
- Ad spend allocated per order — often the largest variable cost for an ecommerce seller, since acquiring each new buyer costs money. Many sellers mentally file marketing as "overhead," but if you spend more to sell more, it behaves like a variable cost — and it usually dwarfs the others. POD sellers must budget for several key areas: platform fees, COGS, design costs, shipping fees, ad spend to drive traffic, and other costs such as domains, fulfillment apps, and transaction fees.
Variable fulfillment cost: the per-order breakdown
Fulfillment is where most POD sellers undercount their variable costs. The true variable fulfillment cost per order is not just the carrier label — it is every touch between the order arriving and the parcel leaving. According to Racklify's logistics encyclopedia, variable cost per order equals picking cost plus packing cost plus packaging materials plus average carrier fee plus handling fees plus an average return provision.
For POD sellers on Printify or Printful, the supplier handles pick, pack, and ship — which bundles most of those lines into the supplier's quoted fulfillment fee. That is convenient, but it also means the number is opaque. Interrogating your order-level data to find the real per-SKU fulfillment cost is the first step to knowing whether a product line is actually viable.
A few fulfillment-specific traps to watch:
- Dimensional weight: not accounting for how carriers charge for volume can lead to surprise costs on lightweight but large packages.
- Return costs: returns can double the variable cost of an order if you are absorbing the inbound label.
- Crude averages: averaging costs across all orders hides expensive outliers — bulky items or high-return SKUs.
- SKU rationalization: identify costly-to-fulfill SKUs and evaluate pricing, bundling, or discontinuation.
The variable cost ratio
A metric worth tracking alongside raw variable costs: the variable cost ratio. It expresses variable costs as a percentage of net sales:
Variable Cost Ratio = (Total Variable Costs ÷ Net Sales) × 100
A lower ratio means more revenue remains after covering variable costs — available for fixed costs and profit. The ratio serves as a useful evaluation metric to determine break-even points, minimum profit margins, profit projections, and the optimal sales price for products. Track it month over month and you can see immediately whether your cost structure is tightening or loosening as you scale.
How to calculate variable costs
The formula is simple:
Total variable cost = variable cost per unit × number of units sold
The work is in getting the per-unit number honest. The table below shows illustrative figures for one example order on a forty-dollar sale. The processing fee uses the published Stripe rate of 2.9% + $0.30; all other lines are example inputs you should replace with your own real numbers.
| Variable cost line | Amount (illustrative) |
|---|---|
| Product (COGS) | $16.00 |
| Shipping | $5.00 |
| Payment processing (2.9% of $40 + $0.30, per Stripe) | $1.46 |
| Pick and pack / fulfillment fee | $1.40 |
| Variable cost before ads | $23.86 |
| Allocated ad spend | $10.00 |
| Total variable cost per order | $33.86 |
Run the arithmetic and the picture is stark. On a forty-dollar order, $40 − $33.86 = $6.14 is left before a single dollar of rent or salary is paid. That $6.14 is the money that has to cover all your fixed costs and, eventually, your profit.
If you sell a thousand of those orders in a month, total variable cost is $33.86 × 1,000 = $33,860. That figure scales with every order — which is exactly why it deserves as much attention as your revenue line.
Average variable cost
Beyond total variable cost, it is worth knowing your average variable cost (AVC) — the variable cost per individual unit at your current volume:
Average variable cost = Total variable cost ÷ Total units produced
AVC matters because it is the floor your price must clear before you contribute anything toward fixed costs. If your AVC rises as you scale — because, for example, you are paying rush shipping or your ad cost-per-order is climbing — that is an early warning that something in your cost structure needs attention. For POD sellers, watching AVC against your supplier's base cost is a quick sanity check; our Printful cost breakdown covers how that floor moves with different product categories.
What is a good variable cost?
There is no universal "good" dollar figure for variable costs, because it only means anything relative to your price. A twenty-four-dollar variable cost is excellent on an eighty-dollar order and fatal on a thirty-dollar one.
The number to judge is your contribution margin — revenue minus all variable costs — expressed as a share of the sale. Prices must be set so that the contribution margin is greater than zero, or else a business will have no opportunity to generate a profit. In the illustrative example above, contribution before ads is $40 − $23.86 = $16.14; after ads it is $6.14.
A healthy target for many product stores is to keep total variable costs low enough that contribution margin after ads stays comfortably positive. If ad spend alone pushes your variable costs past the point where each order still contributes, you are scaling losses, not sales.
So the honest answer to "what is a good variable cost?" is: whatever leaves you a contribution margin you can build a business on. Chase the ratio, not the raw dollar amount.
Why variable costs decide your profit
Variable costs are what set your break-even point — the number of orders you need before fixed costs are covered and profit begins.
The formula is: break-even units = fixed costs ÷ contribution margin per order. Say your fixed costs are four thousand dollars a month and each order contributes $6.14 after variable costs (using the illustrative example above). You need $4,000 ÷ $6.14 ≈ 652 orders just to reach zero. Every order after that is profit; every order before it is you funding the business.
Shave two dollars off your variable cost per order and contribution jumps to $8.14 — dropping break-even to $4,000 ÷ $8.14 ≈ 492 orders. A small cut to variable cost moves your break-even far more than a small bump in price does, because it compounds across every single order.
A business with high variable costs relative to net sales may not yield substantial profits from sales — making it critical to manage these costs actively rather than letting them drift upward with revenue.
The trap is that these costs live in multiple places: your supplier, your carrier, your payment processor, and your ad platforms. Almost no one totals them per order in real time, so "profitable" gets judged on revenue and gross margin alone — and the ad-spend line, the biggest variable cost, gets left out. That is precisely how a growing store can bleed cash.
Variable costs for print-on-demand sellers
POD stores have a variable cost structure that is different from inventory-based merchants — and in some ways more exposed. A business with mostly variable costs can scale up or down with less financial risk than one carrying heavy inventory — but the flip side is that there is no bulk-buy discount to compress your per-unit floor. You pay the supplier's base price, fulfillment, and often international shipping on every single unit.
That means your contribution margin per order is the primary lever on profitability. A few areas to focus on:
- Supplier base cost — compare Printify and Printful across your SKUs. Our Printful cost breakdown and Printful pricing breakdown show where the per-unit floor sits on common products.
- Platform and plan fees — Printify's premium plan changes your per-order cost structure. See our Printify coupons breakdown and Printful Growth Plan pricing guide to decide whether an upgrade improves your unit economics.
- Shipping threshold strategy — offering free shipping above a basket size converts well but shifts shipping cost to your variable stack. Our Printful free shipping breakdown walks through when it helps versus hurts margin.
- Ad cost per order — for POD sellers running paid ads, the ad-spend component of variable cost is often the largest single line. Improving ROAS on Meta directly reduces your variable cost per acquired order. Our guides on Meta seasonal campaign strategy for POD and Shopify Facebook Ads automation for POD cover how to approach that.
- Attribution accuracy — bad attribution data leads to poor bid decisions and inflated effective ad cost per order. Our Shopify + GA4 + Meta Ads setup guide is worth checking if you suspect your numbers are off.
Where PodVector fits
Totaling true variable cost per order by hand is tedious and error-prone, because the numbers sit in separate systems. PodVector connects Shopify, Meta Ads, Google Ads, Printify, Printful, and Klaviyo into a live data warehouse, then computes the per-order economics after every one of those variable costs — product, shipping, fees, fulfillment, and ad spend included.
Victor, PodVector's AI employee, reads that live data, flags where variable costs are eating your margin, and proposes the moves worth making. Victor is not a dashboard you have to interpret; he analyzes the data and, with your approval, takes Shopify-side actions — repricing low-margin SKUs, bulk-updating prices to a target margin, or adjusting your free-shipping threshold. He reads your Meta and Google Ads data to identify cost problems, but all ad account writes are proposed for you to action — Victor never touches your ad accounts directly.
If you want to see your real contribution margin per order instead of guessing, start with PodVector and let the numbers add themselves up.
FAQs
Is labor a variable or fixed cost?
It depends on how you pay for it. Hourly or per-order labor that scales with volume — like pick-and-pack staff paid by the shipment — is variable. A salaried manager who earns the same in a slow month is a fixed cost. Direct labor is frequently not a variable cost, since a minimum number of people are needed to staff a production area, which can make it behave as a fixed cost.
Is shipping a variable cost?
Yes. Carrier and fulfillment shipping charges rise with every order you send and fall to zero when you send none, which is the textbook definition of a variable cost. Any flat-rate warehouse rent tied to shipping, however, is fixed. The variable shipping costs and inconsistent timelines for order delivery can potentially lower profit margins for POD sellers in particular, making carrier selection and shipping zone management worth regular review.
Are variable costs the same as cost of goods sold?
No. COGS is one variable cost — the direct product cost — but variable costs are broader, also including shipping, payment fees, per-order labor, and allocated ad spend. All of COGS is variable, but not all variable costs are COGS.
Is marketing a fixed or variable cost?
Ad spend that you scale up to sell more behaves like a variable cost, because it moves with volume. A fixed annual retainer for an agency or a flat software subscription is a fixed cost. Most sellers underestimate how much of their marketing is truly variable.
Are print-on-demand production costs fixed or variable?
They're variable. A fulfillment partner is only paid when an order is placed and produced, so there's no fixed inventory cost sitting on the books beforehand. This is what makes POD an attractive low-risk model — but it also means every order you send carries its full variable load, with no volume discount compressing that floor.
What is the variable cost ratio?
The variable cost ratio is your total variable costs divided by net sales, expressed as a percentage. A lower ratio means more leftover revenue for fixed costs and profit after the business pays its variable costs. Track it month over month to see whether your unit economics are improving as you scale.
How do I lower my variable costs?
Attack the biggest lines first: negotiate supplier COGS, tighten shipping through better rates or lighter packaging, and — usually the largest lever — improve ad efficiency so acquisition cost per order falls. Even a small per-order cut compounds across every sale, which is why it moves break-even faster than a price increase. Track costs by SKU, channel, and day to catch seasonal spikes and hidden expenses. For POD sellers, also review whether a supplier's premium plan meaningfully reduces your per-unit cost — our Printful Growth Plan pricing breakdown and Printify coupons guide are good starting points.