Low Stock Alerts

Overview

Low stock alerts notify you when inventory drops below a threshold so you can reorder before running out. Every major platform has this built in — Shopify, WooCommerce, and BigCommerce all send email notifications when stock falls below a configured level. For more advanced needs like demand-based thresholds, supplier PO automation, or team notifications in Slack, dedicated apps add those capabilities without custom code.

When to Use This Skill

• When products are unexpectedly running out of stock and missing sales
• When the current inventory workflow relies on manual checks rather than automated alerts
• When you want demand-based reorder points rather than fixed thresholds
• When the store has supplier lead times that need to be factored into when to reorder

Core Instructions

Step 1: Determine platform and choose the right tool

Platform	Built-in Alerts	Recommended Extension
Shopify	Shopify sends an email notification when stock hits zero; very limited threshold control	Stocky (free, by Shopify) for configurable thresholds and PO automation; Back in Stock for customer notifications
WooCommerce	WooCommerce emails the store admin when stock drops below the configured low-stock threshold	ATUM Inventory Management for per-product thresholds, supplier emails, and reorder suggestions
BigCommerce	Built-in low stock notifications per product with configurable threshold	Multi-Location Inventory app for location-specific alerts
Custom / Headless	Build a background job that checks levels against reorder points	Required when platform has no native alerting or you need supplier email automation

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Step 2: Platform-specific setup

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Shopify

Built-in low stock notification:

Shopify sends an email to the store admin when inventory hits zero, but doesn't support configurable thresholds natively.

1. Go to Settings → Notifications → Scroll to Staff order notifications
2. Ensure the admin email is set — Shopify will notify this address when stock reaches 0

Setting per-variant thresholds with Stocky:

1. Install Stocky from the Shopify App Store (free)
2. Open Stocky and go to Products
3. For each product, set the Reorder point (the stock level that triggers an alert)
4. Set the Reorder quantity (how many units to order when the alert fires)
5. Stocky will flag products below their reorder point in the dashboard and can generate draft purchase orders automatically

Customer "back in stock" notifications:

• Install Back In Stock (paid) or Klaviyo from the App Store
• These apps show a "Notify me when available" button on out-of-stock products
• Automatically email opted-in customers when stock is replenished

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WooCommerce

Configure global low-stock threshold:

1. Go to WooCommerce → Settings → Products → Inventory
2. Enter a value in Low stock threshold (e.g., 10)
3. Enter your notification email in Notification recipient(s) — comma-separate multiple emails
4. WooCommerce sends an email when any product drops to or below this threshold

Set per-product thresholds:

1. Go to WooCommerce → Products → [Product] → Inventory tab
2. Enable Manage stock?
3. Enter a Low stock threshold specific to this product (overrides the global setting)

Advanced alerting with ATUM:

1. Install ATUM Inventory Management for WooCommerce (free)
2. ATUM's dashboard shows all products at or below their reorder point in one view
3. Per-product reorder point configuration under ATUM → Product Settings
4. ATUM can also email your supplier directly when a product needs reordering (paid feature)

Demand-based thresholds:

• Install Inventory Planner (Shopify/WooCommerce) for sales velocity-based reorder suggestions
• Inventory Planner analyzes your sales history and suggests reorder points based on lead time × daily velocity + safety stock

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BigCommerce

Set per-product low stock threshold:

1. Go to Products → [Product] → Inventory tab
2. Set the Low stock level field
3. BigCommerce sends an automatic email notification to the store admin when stock crosses this threshold

Configure who receives alerts:

1. Go to Store Setup → Store Settings → Miscellaneous
2. Set Low stock email address to your purchasing team's email

For location-specific alerts:

• Install the Multi-Location Inventory app
• Set thresholds per location — useful when you stock the same SKU at multiple warehouses

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Custom / Headless

For custom platforms, implement a background job that checks inventory levels against configured reorder points:

// jobs/checkStockLevels.ts — run every 15-30 minutes via cron
export async function checkStockLevels() {
  const levels = await db.inventoryLevels.findMany({
    include: { reorderConfig: true, variant: { include: { product: true } }, location: true },
    where: { reorderConfig: { isNot: null } },
  });

  const newAlerts = [];

  for (const level of levels) {
    const config = level.reorderConfig!;
    const available = level.onHand - level.reserved;

    // Dynamic reorder point based on sales velocity and lead time
    let reorderPoint = config.reorderPoint;
    if (config.useDynamicReorderPoint) {
      const velocity = await calculateDailySalesVelocity(level.variantId, 30); // 30-day rolling average
      reorderPoint = Math.ceil(velocity * config.leadTimeDays * 1.2); // 20% safety stock buffer
    }

    const alertType = available === 0 ? 'out_of_stock' : available <= reorderPoint ? 'low_stock' : null;
    if (!alertType) continue;

    // Only create a new alert if the previous one is resolved
    const existingAlert = await db.stockAlerts.findFirst({
      where: { variantId: level.variantId, locationId: level.locationId, alertType, resolvedAt: null },
    });

    if (!existingAlert) {
      newAlerts.push({ level, config, available, reorderPoint, alertType });
      await db.stockAlerts.create({ data: {
        variantId: level.variantId, locationId: level.locationId,
        alertType, triggeredAt: new Date(), availableAtTrigger: available,
      }});
    }
  }

  if (newAlerts.length > 0) await sendAlertNotifications(newAlerts);
}

// Calculate daily sales velocity from order history
async function calculateDailySalesVelocity(variantId: string, windowDays: number) {
  const since = new Date(Date.now() - windowDays * 86400000);
  const result = await db.orderLineItems.aggregate({
    where: { variantId, order: { createdAt: { gte: since }, status: { in: ['completed', 'shipped'] } } },
    _sum: { quantity: true },
  });
  return (result._sum.quantity ?? 0) / windowDays;
}

// Send consolidated alerts — group by supplier to avoid email spam
async function sendAlertNotifications(alerts: Alert[]) {
  const bySupplier: Record<string, Alert[]> = {};
  for (const alert of alerts) {
    const key = alert.config.supplierId ?? 'merchant';
    if (!bySupplier[key]) bySupplier[key] = [];
    bySupplier[key].push(alert);
  }

  for (const [supplierId, supplierAlerts] of Object.entries(bySupplier)) {
    const to = supplierId === 'merchant' ? process.env.MERCHANT_ALERT_EMAIL : (await db.suppliers.findById(supplierId))?.email;
    if (!to) continue;
    await emailService.send({ to, template: 'low-stock-alert', data: { alerts: supplierAlerts } });
  }
}

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Step 3: Calculate dynamic reorder points (optional)

Fixed thresholds (e.g., "alert at 10 units") are simple but can be wrong — a product that sells 50 units per day needs a much higher threshold than one that sells 2 per week.

Formula:

Reorder Point = (Daily Sales Velocity × Lead Time Days) × 1.2 (20% safety buffer)

Example: Product sells 5 units/day, supplier lead time is 7 days

• Demand during lead time: 5 × 7 = 35 units
• Reorder point with safety buffer: 35 × 1.2 = 42 units

For Shopify: Use Inventory Planner app — it computes velocity-based reorder points automatically from your sales history.

For WooCommerce: ATUM Inventory Management can be configured with supplier lead times and suggests reorder points based on sales velocity.

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Step 4: Automate reorder notifications to suppliers

Once an alert fires, you want to notify your purchasing team or supplier automatically.

Shopify + Stocky: Stocky generates draft purchase orders when stock falls below the reorder point. Your team reviews and sends the PO to the supplier from within Stocky.

WooCommerce + ATUM (paid): ATUM can email the configured supplier directly when a product needs reordering, including the suggested quantity.

Email workflow (any platform): Set the low-stock notification email directly to your supplier's ordering inbox — include the SKU, product name, and suggested reorder quantity in the notification template.

Best Practices

• Set reorder points based on lead time and sales velocity — a fixed threshold of 10 units may be fine for slow movers but dangerously low for fast sellers; use the formula above as a starting point
• De-duplicate alerts — platforms and custom solutions should only send one alert per SKU per incident, not an alert on every inventory decrement; resolve old alerts when stock is replenished
• Consolidate supplier emails — one email with 5 low-stock SKUs from the same supplier is far less noisy than 5 separate emails
• Set thresholds at the variant level, not just the product level — a shirt with 3 remaining in XL and 50 in M should alert only for XL
• Review and update thresholds seasonally — a product that sells 2/day normally may sell 20/day during peak season; adjust thresholds before high-demand periods

Common Pitfalls

Problem	Solution
Alert fires repeatedly for the same SKU	Ensure the platform only sends one alert per incident until stock is replenished; Shopify and WooCommerce do this correctly by default; custom builds need a resolvedAt guard
Dynamic reorder point too high during off-season	Use a rolling 30-day window for velocity calculations; consider separate seasonal configurations for products with strong seasonality
Supplier emails go to spam	Use an authenticated sending domain (SPF, DKIM, DMARC) for your alert emails; transactional email providers (SendGrid, Postmark) improve deliverability
Alert threshold too low — too many false alarms	Start with a threshold at 2× your typical order quantity from the supplier, then tune based on how often you're actually running out before the reorder arrives

Related Skills

• @inventory-tracking
• @multi-warehouse
• @catalog-import-export