Restock forecasting for brands that run on spreadsheets
Know exactly when to reorder every SKU
Try it right here — this is the real calculator, prefilled with example numbers. Swap in yours and the date updates instantly.
- Days you have left to order
- 2 days
- Projected stockout date (if you never reorder)
- Thu, Aug 27, 2026
- Total runway at current sales speed
- 30 days
Runs entirely in your browser — nothing you type is sent anywhere.
Want this for every SKU, without the tab-juggling?
The bulk forecaster is in development — one CSV upload will return this date for your whole catalog, plus an email before each one comes due. Join the waitlist and the first 50 members lock founding pricing at $19/mo.
Stockouts bleed rankings; overstock buries cash. ShelfOwl turns sales speed, supplier lead time and safety stock into the one number spreadsheets never surface — the last calendar day you can safely place each purchase order.
Free forever for single-SKU math. No store connection, no plugin, no signup — results compute in your browser and every formula is published.
The spreadsheet tells you what you sold. It doesn’t tell you when to reorder.
Reorders run on gut feel
“Looks low, better order” is how stockouts and overstock both happen. The math behind a correct reorder — daily sales × lead time + buffer — is simple, but nobody runs it weekly for 60 SKUs by hand. That is what restock forecasting automates.
Margins are guesses
Fees, ads, returns and packaging hide between the supplier invoice and the payout. Sellers routinely overestimate margin — and then reorder the wrong SKUs. True COGS comes first; restock timing second.
Existing tools miss the middle
Enterprise inventory planners want a sales call and a four-week onboarding. Plugin tools lock you into one platform’s ecosystem. The middle — self-serve, CSV-in, answer-out — is where ShelfOwl sits.
This is what a restock forecast looks like
Waitlist open — not yet buyableExample data, showing the format the bulk forecaster will return. One CSV of sales, stock and lead times in — this table out: every SKU’s remaining runway and the last safe day to place its purchase order, riskiest first. The two amber rows are the whole point: they are the orders you would have discovered too late. Notice the hoop earrings — 27 days of runway sounds relaxed until a 35-day supplier lead time turns it into an order that is already overdue. Runway alone is a comfortable lie; runway minus lead time is the truth.
- Linen shirt — navy / MAug 746d runway
5.2/day · 240 on hand · 28d lead time
- Candle — cedar 8ozAug 1136d runway
11.4/day · 420 on hand · 14d lead time
- Ethiopia beans 12ozJul 14 — order now14d runway
8.8/day · 130 on hand · 21d lead time
- Hoop earrings — goldJul 12 — order now27d runway
2.1/day · 58 on hand · 35d lead time
- Whey vanilla 2lbAug 1358d runway
6.5/day · 380 on hand · 30d lead time
The math behind each row is the same published formula as the free calculator above. The bulk version that runs it across your whole catalog is still in development, gated on real demand signals rather than a roadmap fantasy — which is why this page offers a waitlist instead of a checkout. Planned pricing is $29/mo with a 14-day trial and no card. See the plan
Free calculators that answer real restock questions
Each tool is a full worked answer: the calculator, the formula spelled out, a worked example and an FAQ. Use them in any order — they chain together into a restock forecasting workflow.
- True COGS CalculatorCalculate your true COGS per unit — landed cost, marketplace fees, payment fees, ad spend, returns and packaging — and see your real gross margin per order.Open calculator →
- Reorder Point CalculatorWork out the exact inventory level that should trigger your next purchase order: daily sales × supplier lead time + safety stock. Free reorder point calculator, no signup.Open calculator →
- Safety Stock CalculatorCalculate how many buffer units protect you from demand spikes and late suppliers, using the max-sales × max-lead-time method. Free safety stock calculator, no signup.Open calculator →
- Latest Order Date CalculatorThe one question no dashboard answers: the last calendar day you can place a PO before this SKU stocks out. Current stock, sales speed, lead time in — a date out.Open calculator →
- Etsy Profit CalculatorSee your real profit per Etsy order after transaction, listing, payment processing and Offsite Ads fees — 2026 rates with sources.Open calculator →
- Inventory Turnover CalculatorInventory turnover ratio and days of inventory on hand from your annual COGS and average inventory value. See if your cash is moving or parked on shelves.Open calculator →
How restock forecasting works — four numbers, one date
There is no machine learning here and no black box. Restock forecasting for a small catalog is four honest calculations chained together — each one is a free calculator on this site, each formula is spelled out on the methodology page, and every formula ships with automated test fixtures so the published math and the running code cannot quietly drift apart.
- STEP 1
Measure sales velocity
Units sold over the last 30–90 days ÷ days in the window, per SKU. Exclude out-of-stock days or the number lies to you.
- STEP 2
Size the safety buffer
Worst observed demand × worst observed lead time, minus the averages — the safety stock calculator does it from four inputs.
- STEP 3
Set the trigger level
Daily sales × supplier lead time + safety stock = the reorder point: the stock level that should fire a purchase order.
- STEP 4
Get the date
Convert it to a calendar day: today + (stock − safety stock) ÷ daily sales − lead time. That is the latest order date — the number the hero calculator just showed you.
Built to be checked, not believed
Every formula is public
The exact arithmetic behind every calculator — reorder points, safety stock, latest order dates, true COGS — is documented on the methodology page. If you disagree with a formula, you can see precisely what to disagree with.
Fee rates carry receipts
Prefilled marketplace rates link to the official pricing page they came from, with the date we verified them — all on the sources page, with changes logged on rate updates. And every rate stays editable.
Your data stays yours
Free calculators run entirely in your browser: zero network requests to produce a result — open your browser’s network tab and watch nothing happen. No store OAuth, ever. The only thing we store is an email address, and only if you choose to join the waitlist.
Made for the brands spreadsheets were failing
ShelfOwl is for SMB ecommerce operators with tens to a few hundred SKUs and no ERP — the exact zone where restock forecasting matters most and tooling is thinnest. If your inventory truth lives in a spreadsheet and reorders get decided by scrolling it, you are exactly who this site was built for.
- Apparel brands juggling size/color variants and seasonal buys — forecasting guide
- Coffee roasters timing green-bean orders around roast schedules — restock alerts guide
- Handmade & jewelry sellers balancing materials and made-to-order queues — order management guide
- Marketplace sellers on Etsy, Amazon or TikTok Shop who need fee-true margins — start with fees
Why not an inventory platform or a store plugin?
Versus enterprise planners
Full inventory platforms are excellent at multi-warehouse planning — behind a quote-based sales process and weeks of onboarding. If you manage a few hundred SKUs in Google Sheets, you do not need an implementation project; you need answers this afternoon. ShelfOwl is self-serve by design: calculators now, one CSV upload when you outgrow them.
Versus single-platform plugins
Plugin forecasters read one store’s API — great until your inventory lives across Shopify, Etsy, wholesale and a 3PL. ShelfOwl works from a CSV precisely so it works for everyone: multi-channel sellers, pre-launch brands, even wholesale-only operators. No integration to break, nothing to uninstall.
Start free today. The bulk version is still being built.
Run any calculator free, forever — no account, no usage cap, no email wall, and nothing you type ever leaves your browser. The bulk forecaster for people juggling more SKUs than browser tabs is not built yet: it will be $29/mo (or $290/yr) with a 14-day trial and no card, and the first 50 waitlist members will lock founding pricing at $19/mo. Joining the waitlist costs nothing, commits you to nothing, and tells us which parts to build first.
Or see what’s in the paid plan.