Inventory how-to

How to plan inventory around paid ads spend increases

Before you increase ad spend, work out what daily sales rate the new spend is supposed to produce, then check if your inventory and your suppliers' lead times can actually support that rate.

Short answer: Before you increase ad spend, work out what daily sales rate the new spend is supposed to produce, then check if your inventory and your suppliers' lead times can actually support that rate. If stock cannot arrive in time, either delay the spend increase, order early, or cap the ad budget to what you can fulfill.

Why this matters more than it seems

A sales forecast built on the last 28 days of normal sales will not predict a demand spike from new ad spend. If you turn up ad budget and the forecast has not caught up yet, your order-by dates and suggested quantities will be based on old, lower sales. You will run out of stock exactly when the ads are working.

Work backwards from the ad goal

Start with the number, not the ad budget. If you plan to spend enough to roughly double traffic to a product page, estimate the resulting daily sales rate using your current conversion rate, not a guess. Then check that number against your current days of stock and your supplier's lead time plus safety days. If the reorder point based on the old daily sales has already been reached, you are already late for the higher rate.

Build a buffer before you switch spend on

Treat a planned ad increase like a known future event, similar to a promotion. Place a purchase order sized for the expected higher daily sales before you increase spend, not after you see the first few days of results. Ramp spend gradually where you can, so actual sales data starts confirming or correcting your estimate while there is still time to place a second order.

Watch the first week closely

Once spend is up, compare actual daily sales to your estimate every few days. If sales are running above forecast, reorder early rather than waiting for the normal reorder point, since that point was set using pre-increase numbers. If sales are below the estimate, you can hold off on the next order and avoid overstocking.

Step by step

  1. List the products the ad campaign will push and check current days of stock for each.
  2. Estimate the daily sales rate the new ad spend should produce, based on expected traffic and your normal conversion rate.
  3. Calculate reorder point and order quantity using the estimated higher daily sales, not the current 28-day average.
  4. Place the purchase order early enough to land before the ad spend increase starts, factoring in full lead time plus safety days.
  5. Ramp ad spend in stages if possible, so you can confirm the sales rate before committing to a second order.
  6. Track actual daily sales against your estimate for the first one to two weeks and reorder early if sales run ahead of plan.
  7. Cap or pause spend increases on any SKU where supplier lead time is too long to realistically catch up.

Worked example

A store sells a water bottle at 6 units a day and has 90 units on hand, with a supplier lead time of 14 days and 3 days safety stock. Normal reorder point is 6 x (14 + 3) = 102 units, so they are about to reorder anyway. They plan to double ad spend on this product, estimating it will push daily sales to 12 units a day. Using the higher rate, reorder point becomes 12 x 17 = 204 units, well above the 90 on hand, so they place an order sized for 12 units a day of cover before switching on the extra spend, rather than waiting for the old reorder point to trigger.

How SteadyShelf helps

SteadyShelf forecasts from your actual 28-day sales history, so it will not predict a demand jump from an ad spend increase you have not launched yet. You need to estimate the new daily sales rate yourself and either place an early manual order or temporarily adjust order quantities until the higher sales pattern shows up in the data and the forecast catches up.

$29/month flat, unlimited products and suppliers, 30-day free trial. Run the numbers now with the free reorder point calculator.

SteadyShelf is launching on the Shopify App Store. Join early access to get the install link first.

Related guides

All inventory how-to guides ยท Inventory glossary

FAQ

Will SteadyShelf automatically raise order quantities once ad-driven sales come in?

Yes, once the higher sales show up in the rolling 28-day window, forecasts and suggested order quantities will adjust upward. The issue is the lag before that data accumulates, so for a sudden planned spend increase you should order ahead manually rather than rely on the forecast alone.

Should I increase ad spend and inventory for every SKU at once, or just a few?

Focus on a small number of SKUs where you can confidently estimate demand and where your supplier's lead time is short enough to respond. Spreading a spend increase across many SKUs makes it harder to forecast each one accurately and harder to keep every reorder point correctly adjusted.

Let SteadyShelf do this math for every SKU

Order-by dates per supplier, seasonal forecasts and draft POs for your Shopify store. $29/month after a 30-day free trial.

Get early access