Short answer
Reorder when stock falls to your reorder point, not when it
looks low. The reorder point is how much you will sell while you wait for the delivery, plus a buffer:
(average daily sales × lead time in
days) + safety stock
Shopify tracks how much stock you have. It does not work out
when that number becomes a problem, because it knows nothing about your supplier’s lead time, minimum order or case
size. That calculation is on you — or on an app.
Why “it looks low” is the wrong trigger
Most small stores reorder on instinct: someone notices a bin is nearly empty and emails the supplier. That works
until two things collide — a product that sells faster than you remember, and a supplier who takes longer than
you remember. Then you are out of stock for three weeks, and the listing that was ranking quietly loses its
position.
The fix is not more diligence. It is deciding, per product, the stock level at which ordering becomes urgent, and
letting that number tell you rather than your memory.
What Shopify gives you
Accurate quantities on hand, per location, and the ability to see what has sold. That is genuinely the hard
part — and it is where the native tooling stops.
What it does not know
Your supplier’s lead time, their minimum order quantity, case sizes, order cutoff days, or how erratic demand
for a given SKU is.
What that means
Shopify can tell you that you have nine left. It cannot tell you that nine is already too late for a product
with a 21-day lead time.
Three ways to run this
| Approach | Rating | Cost | Breaks down when |
|---|---|---|---|
| Shopify admin alone | — | Free | Immediately — it has no lead-time or supplier data |
| Spreadsheet | — | Free, plus your time | Past ~100 SKUs, or a second supplier |
| Reordio | No reviews yet (launched Aug 2026) | $19/mo, 14-day trial | If your lead times are guesses rather than measured |
App details verified against the live App Store listing, 11 August 2026.
The reorder point, worked through properly
Two numbers, then a decision. Both come from data you already have.
Step 1: average daily sales
Take a representative period — 30, 60 or 90 days — and divide units sold by the number of days. Use
a longer window for slow movers and a shorter one for anything trending. If the product is seasonal, use the same
period last year rather than last month.
Step 2: lead time
The days between placing the order and the stock being sellable. Count everything: the supplier’s production or
dispatch time, transit, customs if you import, and your own receiving time. That last one is the most commonly
forgotten — a pallet sitting unbooked in the stockroom is not sellable stock.
Step 3: safety stock
The buffer that absorbs a bad week or a late delivery. A practical formula:
average lead time)
In other words: the difference between your worst realistic case and your typical case. If your sales and your
supplier are both steady, this number is small. If either is volatile, it is not.
Step 4: the reorder point
A worked example
You sell a candle that moves 4 units a day
on average, peaking at 9. Your supplier normally takes 14 days, but has stretched
to 21.
Safety stock = (9 × 21) − (4 × 14) = 189
− 56 = 133 units.
Reorder point = (4 × 14) + 133 = 189 units.
So you reorder at 189 — not at 20, and not when the shelf looks
thin. If that number feels uncomfortably high, the honest read is that your supplier’s variability is expensive,
and the cheaper fix may be a more reliable supplier rather than more capital tied up in stock.
Then reality intervenes
The formula gives you a trigger. It does not give you an order. Three things usually stand between the two, and
they are why spreadsheets get abandoned.
- Minimum order quantity. You need 189 but the supplier sells in units of 500.
- Case size. You need 189 but they ship in cases of 24, so you are ordering 192.
- Order cutoffs and delivery days. Miss Thursday’s cutoff and your 14-day lead time quietly
becomes 18.
A spreadsheet can hold all of this. It just rarely survives contact with a growing catalogue, because every SKU
needs its own maintained lead time and every supplier changes terms occasionally.
Automating it
Reordio is built specifically for this calculation on Shopify. It reads your inventory and sales
and produces a single reorder list: which products need ordering now or within seven days, how much to order, and
why — with the full calculation visible rather than hidden behind a recommendation. It accounts for lead time,
safety stock, case size and minimum order, and for supplier order cutoffs and delivery days. When goods arrive,
Shopify inventory flows back in on the next sync.
One reorder list: what to order now or soon, how much, and the arithmetic behind each suggestion.
Every suggestion exposes its inputs, so you can check the lead time and safety stock it used.
Supplier lead times, cutoffs and delivery days are settings, not assumptions.
The vendor is explicit about what it is not, which is worth respecting: it does not place supplier orders
and it is not an ERP. It tells you what to buy. You still send the purchase order.
Pros ✓
- Shows the complete calculation, so you can sanity-check a suggestion instead of trusting a black box
- Handles the parts that break spreadsheets: case size, minimum order, cutoffs, delivery days
- Rounds suggestions to what you can actually order rather than a theoretical number
- Carries the Built for Shopify badge
- 14-day trial, which is long enough to watch one real ordering cycle
Cons ✗
- Zero public reviews — the listing went live on 7 August 2026, so there is no track
record at all yet - No free plan; $19/month from day one after the trial
- Does not place orders or talk to suppliers — it is a planning tool, not procurement
- English only, and works with Shopify Admin rather than a wide integration list
- Garbage in, garbage out: if your lead times are guesses, so are its recommendations
See Reordio on the App Store →
Partner link · $19/mo · 14-day trial
Try Reordio free for 14 days →Partner link · check its numbers against your own during the trial
Bottom line
Our verdict: do the maths by hand first, on your ten
best-selling products. It takes an afternoon, costs nothing, and prevents most stockouts on its own — because
those ten products are where the money is.
Automate once the spreadsheet stops being maintained, which usually
happens somewhere past a hundred SKUs or a second supplier. If you get there, Reordio is built for
exactly this job and shows its working, which is the right design. Just be clear that at zero reviews you would be
an early adopter, and use the 14-day trial to check its numbers against your own.
Frequently asked questions
How do I know when to reorder stock on Shopify?
Reorder when on-hand stock reaches your reorder point, calculated as (average daily sales × supplier lead
time in days) + safety stock. Shopify tracks your quantities accurately but has no knowledge of supplier lead times,
minimum orders or case sizes, so the trigger level has to be calculated by you or by an inventory planning
app.
What is the reorder point formula?
Reorder point = (average daily sales × lead time in days) + safety stock. A practical way to derive safety
stock is (maximum daily sales × maximum lead time) − (average daily sales × average lead time),
which sizes the buffer to how unpredictable your demand and your supplier actually are.
Does Shopify have low stock alerts?
Shopify shows inventory levels per location and surfaces low quantities in the admin, and some plans and
channels expose additional notifications. What it does not do is calculate a per-product reorder point from your
sales velocity and supplier lead time, which is the number that actually tells you when to act. Confirm what your
own plan includes before relying on it.
How much safety stock should I hold?
Enough to cover the gap between a normal week and a bad one. Use (max daily sales × max lead time) −
(average daily sales × average lead time). If that produces an uncomfortably large number, the underlying
problem is usually supplier variability rather than the formula — and a more reliable supplier is cheaper than
the extra stock.
Do I need an app to plan reorders?
Not at first. A spreadsheet with average daily sales, lead time and safety stock per product handles a small
catalogue perfectly well, and doing it manually teaches you which products are actually volatile. Apps earn their
place when the SKU count or supplier count makes that spreadsheet impossible to keep current — typically past
a hundred products or a second supplier with different terms.
App pricing and details verified against the Shopify App Store on 11 August 2026. Contains a
partner link to Reordio — it never costs you more, and this page recommends doing the calculation yourself
first, which costs nothing at all. Formulas here are standard inventory-management arithmetic, not financial
advice; sense-check them against your own margins and cash position.