3 Ways to Forecast Sales for Q4 (and Other Busy Seasons) in Your Small Business

Most small business owners don’t start their business because they love numbers and spreadsheets. But forecasting your sales is one of the most powerful tools you can use to make sure you stay profitable and in control.

It helps you figure out:

• How much stock you need to order
• Whether your cash flow will cover expenses
• What actions you need to take to actually hit your target

And that’s especially important for big sales periods like Christmas, Black Friday, or generally the final quarter (Q4).

Lucky for you, I’m a Stock and Profit Specialist with 20 years’ experience working with both big brands and small businesses, and I’m passionate about making numbers feel simple, clear, and (dare I say it) fun.

Remember, your forecast doesn’t have to be perfect. You’ll never get it 100% accurate (none of us have a crystal ball), but each time you do it, you’ll understand your business better. And with that knowledge, you can make calmer, clearer decisions to increase sales, manage your stock, and keep more profit.

So, here are three simple ways to forecast your Q4 sales which are methods you can use for your total business, a specific category, or even individual products.

1. The Quick & Easy Way: Average Monthly Sales + Seasonal Uplift

If you’re new to forecasting (or just want a fast method), this is the simplest place to start.

Take your average monthly sales for the year so far, then multiply by a “seasonal uplift” to reflect that Q4 is rarely average,  it’s usually busier.

Formula:
Average Monthly Sales × Seasonal Uplift × 3 (months in Q4)

Example:
Average monthly sales = £2,000
Seasonal uplift = 1.5 (50% increase for Q4)

£2,000 × 1.5 × 3 = £9,000 forecasted Q4 sales

If you’re not sure what uplift to use, try one of these:

• Compare last year’s Q4 to your monthly average.
• Use industry benchmarks (many retailers see 20–50% higher sales in Q4).

If you’re brand new, start conservatively with +25% and adjust next year.

This method gives you a realistic ballpark figure — no complicated spreadsheets required.

2. The Year-to-Date (YTD) Method

If you’ve got at least a full year of sales data, this method builds on what’s already happened in your business.

Many retailers find that Q4 accounts for 30–40% (or more) of their total annual sales. If your products are particularly giftable or seasonal, it might be even higher.

Formula
YTD Sales ÷ (100 – % of forecasted Q4) = Total Year Forecast
Total Year Forecast – YTD Sales = Q4 Forecast

Example
YTD Sales = £600
You expect your Q4 sales will make up 40% of the year.

£600 ÷ 60% (100 – 40%) = £1,000 Total Year Forecast
£1,000 – £600 = £400 Q4 Forecasted Sales

This method is great if you already have a year’s worth of numbers to lean on and it’s especially useful for forecasting at product level so you can plan how much stock to order.

3. The Detailed Method: Using Your Key Metrics

If you prefer a more precise, data-driven approach, this method is for you. It uses your three core metrics to build a forecast based on how your business actually performs:

• Sessions/Footfall (how many people visit)
• Conversion Rate (how many of them buy)
• Average Order Value (AOV) (how much they spend per order)

Formula
Revenue Forecast = (Sessions × Conversion Rate × AOV) ÷ (1 + VAT)

Example (based on last year’s data):
1,000 sessions × 1% conversion = 10 orders
10 orders × £12 AOV = £120 Gross Revenue
£120 ÷ 1.2 (VAT at 20%) = £100 Net Revenue

If your traffic or sales have been trending up this year, adjust the numbers:

Example (adding growth):
Last year’s sessions = 1,000
This year you’ve seen a 10% increase → 1,100 sessions

1,100 sessions × 2% conversion = 22 orders
22 orders × £15 AOV = £330 Gross Revenue
£330 ÷ 1.2 = £275 Net Revenue

This method not only gives you a more accurate forecast but also shows you where to focus if you want to hit your goals:

• Low on traffic? → Work on SEO, PR, emails, or ads.
• Low conversion rate? → Improve product pages, checkout flow, or attract warmer traffic (from Google search and email marketing).
• Low AOV? → Try bundles, upsells, or free shipping thresholds.

By breaking your forecast down into these building blocks, you’ll start to see how small changes, a slightly higher conversion rate or a modest boost in AOV, can make a big difference to your overall sales and profit.

How to Split Your Forecast by Week or Month

Now that you’ve got your overall Q4 sales forecast, you might want a more detailed view, breaking it down by month or week to help with stock planning, marketing, or cash flow.

If you have last year’s sales data, start there. Look at what percentage each week contributed to your total Q4 sales, and apply that same mix to this year’s forecast.

Formula:
(Last Year Week 1 Sales ÷ Last Year Q4 Sales) × 100 = Week 1 Sales Mix %

Example:
Last Year Week 1 Sales = £10
Last Year Q4 Sales = £100
→ Week 1 Sales = 10% of Q4

If this year’s Q4 forecast is £400:
£400 × 10% = £40 This Year Week 1 Forecasted Sales

This approach gives you a realistic week-by-week view that reflects your own business patterns.

If you don’t have last year’s data to go on, don’t worry, you can take an educated guess.

Here’s a suggested starting point based on typical small retail and e-commerce patterns (you can adjust it depending on your last posting dates, delivery cut-offs, and Black Friday/Cyber Monday offers):

Week	Key Period	Suggested % of Q4 Sales
1	Early October	4%
2		4%
3		5%
4	Half-Term / Halloween	6%
5		6%
6	Early Gifting Starts	8%
7	Pre–Black Friday Build Up	10%
8	Black Friday Week	15%
9	Cyber Monday / Early Dec Rush	10%
10	Main Christmas Shopping Peak	18%
11	Final Christmas Orders	10%
12	Post-Christmas / New Year	4%

💡 Tip: Once you’ve tracked your actual Q4 results this year, save your data! Next year, you can use your real sales mix instead of estimates.

Forecasting Doesn’t Have to Be Complicated

Whether you use the quick and easy average, the YTD approach, or the detailed data method, the most important thing is simply to start forecasting.

It’s not about getting it perfect,  it’s about getting clear. Clear on what’s realistic, where to focus your time and money, and how to prepare your business for a busy season.

The more often you do it, the better you’ll understand your numbers, your patterns, and your potential. And before long, forecasting will feel less like a guessing game and more like your secret weapon for calmer, smarter growth.