GP percentage calculator for pubs

Last updated: 26 June 2026

Most pub licensees have no idea whether their gross profit is actually 70% or 65% until the accountant tells them in January. You’re running the pub on a hunch, checking stock once a month if you’re lucky, and hoping the till is honest. Here’s the thing: you can calculate your GP percentage every single week in under 10 minutes once you know what to measure. You have that data already — you just don’t know how to connect it. A 1% swing in wet GP costs or saves you roughly £3,000–£5,000 a year in a typical pub. That matters. This article shows you exactly how to build a pub GP percentage calculator that actually works, why it beats spreadsheets, and what numbers you should be watching that your brewery stocktaker won’t tell you.

The GP Percentage Formula That Works

GP percentage = ((Total Revenue − Cost of Goods Sold) ÷ Total Revenue) × 100. That’s it. Simple. But most pubs calculate this once a month or once a quarter and by then the loss is already baked into your bank account.

Here’s what you actually need to do: calculate it weekly, and calculate it by product line. Spirits. Draught. Cider. Soft drinks. Wine. Bottled beer. Each one. Because your draught GP might be solid at 78% while spirits is bleeding at 62%, and a single headline figure of 71% tells you nothing useful.

The formula looks like this in practice:

• Revenue: add up everything your till says you sold this week in spirits (cash + card)
• Cost of Goods Sold: weight the bottles you opened at the start of the week, weight them at the end, work out how many measures you poured, divide by what you sold on the till
• The difference is your variance — it should be tight (within 1–2%), not loose

Most GP calculators you’ll find online assume you have perfect inventory data. You don’t. You have a till that tells you what sold, and you have bottles and casks that tell you what was poured, and the two never quite match because of measurement error, wastage you forgot to log, and over-pouring that happens behind every bar in the country.

Why Line-by-Line Tracking Beats a Single Headline Figure

A headline GP of 72% sounds healthy. But if your spirits — which make up 35% of your wet sales — are running at 58%, you’re losing money on your most profitable product and you won’t know until the year-end audit.

The number that actually matters is wet GP by line because spirits hide losses in over-pouring (a free-poured 25ml is often 32–35ml), draught hides it in poor cellar temperature and bad line cleaning waste, and most stock “theft” is actually measurement error and forgotten wastage. When you track by line, you see the real picture:

• Spirits variance usually points to over-pouring or measuring jugs that are off
• Draught variance usually points to temperature, line cleanliness, or bad pours going down the drain
• Wine variance usually points to undercharging or staff pouring unmeasured free glasses

A single pub-wide GP figure hides all of these. You need to see them separately.

At my own pub I was running stock on a tangle of spreadsheets and still losing track of partial kegs and spirit measures. The variance bounced between 68% and 76% week to week, which told me nothing except that my counting was rubbish. I built a simple routine: weigh every open spirit bottle the same day I dip every cask, reconcile against till data that afternoon, log it in a basic tracker. Within a fortnight the weekly variance sat at 71–72% consistently. I could then see that the actual problem was one member of staff consistently pouring larger spirits. Fixed that, reclaimed 1.5 GP points, and it stayed there.

How to Build Your Weekly GP Calculator

You don’t need software, but you do need discipline. Here’s what a working routine looks like:

Step 1: Collect Till Revenue By Line

Your EPOS or till should split revenue by category. If it doesn’t, ask your provider how to get this report. You need:

• Total spirit sales (£)
• Total draught sales (£)
• Total wine sales (£)
• Total soft drink sales (£)
• Everything else

Print this out on the same day you do your count. Don’t wait.

Step 2: Measure What You Poured

This is where most pubs fail because they estimate stock. You need actual weights:

• Spirits: Weigh every open bottle at the start of the week (keep them in the same spot). Weigh them again at the end. The difference is what you poured. Divide by your standard measure (25ml, 35ml, 50ml — whatever you use). That’s your pours count.
• Draught: Dip every cask and partial keg using a dipstick. Record the inches. Multiply by your cask’s yield per inch (your brewery rep should give you this). The difference between opening and closing dips is what flowed.
• Wine and bottles: Count empties. This is less accurate but it’s better than guessing.

Do this once a week, same day, same time. A Tuesday morning count takes 15 minutes once you build the habit.

Step 3: Calculate Cost of Goods Sold

Multiply your pours count by your cost per measure. If your spirits cost £12 a bottle and a bottle yields 25 measures, your cost per measure is 48p. If you poured 280 measures, your COGS is £134.40.

Do this for every line.

Step 4: Calculate GP for Each Line

For spirits: if you sold £680 worth and your COGS was £134.40, your GP is ((680 − 134.40) ÷ 680) × 100 = 80.2%.

If that’s a surprise, it means your measurement was off or your till wasn’t ringing drinks properly. Find out which.

Common Mistakes That Hide Losses

Mistake 1: Weighing bottles that sit next to a hot till or radiator. Spirit bottles evaporate. A 70cl bottle can lose 10–15ml a week if it’s warm. Move your scales to a cool spot. This accounts for more “variance” than you’d think.

Mistake 2: Not counting staff drinks, comps, or waste separately. If your staff drank 12 spirits this week, write it down. If you comped 6 bottles of wine, log it. If you poured a pint down the sink because the temperature was off, record it. Your till doesn’t see these — your counting does. Your GP calculation should account for them as cost, not as “loss”.

Mistake 3: Relying on brewery stocktake figures. The brewery stocktaker comes once a month or once a quarter. They want to move on. They don’t dip casks in the dark corner. They estimate open bottles instead of weighing them. Their figure will be off by 3–5%, which costs you money. You need weekly data to spot trends, not quarterly data to spot damage that’s already done. StockTap pub stock app was built because brewery stocktakers aren’t checking the things that actually matter to your margin.

Mistake 4: Not flagging temperature and line cleaning as separate costs. If your cellar runs at 22°C instead of 18°C, you lose 2–3% draught GP to waste and poor pours. If your lines aren’t cleaned weekly, you lose more. These aren’t theft — they’re operational. But they still hit your margin.

Tools and Methods That Actually Stick

A spreadsheet works if you’re disciplined. Most licensees aren’t — not because they’re lazy, but because running a pub is chaos. You’re short-staffed, someone calls in sick, a supplier doesn’t show, and suddenly your Tuesday count doesn’t happen and you skip a week of data.

The best pub GP percentage calculator is the one you actually use every week. For me, that’s a simple counting sheet (printed or digital doesn’t matter) and a dipstick and scales that live in the cellar. Takes 15 minutes. I run the numbers the same afternoon and I see the variance before anything goes wrong.

If you’re working from a spreadsheet, set a phone reminder for the same day every week. If you’re using SmartPubTools, use the cellar tracking screen and it syncs with your till data automatically — you just do the physical count and the app works out your variance for you.

The equipment you need:

• A simple kitchen scale (£10). Weigh your open spirit bottles.
• A dipstick (free from your brewery). Dip every cask and partial keg.
• A note pad or a spreadsheet or an app. Write down your numbers the same day.
• Your till reconciliation. Print it out the same day.

That’s it. No fancy equipment. No excuses.

Moving From Spreadsheets to Real Data

Most pubs that move from a messy spreadsheet to a disciplined weekly count routine claw back 1–2 GP points within a couple of months. That’s not magic. That’s catching the stuff your spreadsheet never saw: the regular over-pours, the unmeasured wine pours, the line waste that no one logged.

When you start tracking weekly, you also start spotting patterns. You’ll notice that Friday nights your GP dips because your busiest bartender over-pours when it’s rammed. You’ll see that after a line clean, draught waste drops. You’ll see that one supplier’s spirit bottles pour smaller than another’s, which means your measure is actually 28ml not 25ml, and your cost per drink is wrong.

These are the conversations that actually move your margin. Your brewery rep won’t tell you them. Your accountant won’t see them until year-end. Only you will, if you track it.