Check the forecast
Look at the day’s weather and the seller’s confidence before spending money. Conditions can make the same plan perform very differently.
Player guide
Run your lemonade stand.
Every morning gives you a forecast and one simple problem: decide how much lemonade to make, how much to advertise, and what to charge. Then open the stand, watch the day play out, read the results, and adjust tomorrow.
Quick start
One day takes six steps
You do not need to understand a formula before playing. Read the conditions, make three choices, and use the next report as feedback.
Choose glasses
Decide how many cups to prepare. You pay to make them before you know exactly how many people will buy.
Choose signs
Advertising can bring in more demand, but every sign costs money. Spend only what the day can reasonably earn back.
Set the price
Higher prices earn more per sale but reduce demand. Lower prices attract more buyers but leave less revenue per cup.
Sell for the day
Commit your choices and watch Lemonsville react. Your decisions are locked while the day resolves.
Read the report
Compare prepared versus sold, revenue versus costs, and the ending balance. Then change tomorrow’s plan based on what actually happened.
Your three choices
Everything you control
The daily game deliberately stays small. Weather and confidence matter, but they are conditions to react to—not extra knobs to manage.
Glasses
How much to makePrepared glasses set your maximum possible sales for the day. If demand is higher than your inventory, you sell out. If demand is lower, the unused production cost is already spent.
Signs
How hard to advertiseSigns increase potential demand, but each sign costs $0.50. Advertising can be powerful, especially when the rest of your plan can support the extra customers.
Price
What each cup costsPrice directly trades volume for margin. Raising it reduces potential demand; lowering it can attract more buyers. The best price depends on weather, confidence, inventory, and your available cash.
Starting point: a new stand begins with a $10 operating balance. Each prepared cup costs $1.00. Avoid committing all of your cash at once; you need enough room to recover from a weak day.
Conditions
Read the day before you spend
Weather and confidence can change how much demand your price and advertising produce. Treat them as signals about risk and opportunity.
Weather
Better lemonade weather can multiply demand sharply. Poorer weather can make an aggressive inventory or advertising plan expensive.
Strong weatherYou can consider more inventory, more promotion, or testing a higher price—but you still pay every cost up front.
Weak weatherProtect cash. Smaller production and a more cautious spend can reduce waste when fewer customers are likely to buy.
Confidence
Confidence reflects recent operating performance. Strong results can improve it; weak results can reduce it. Higher confidence helps potential demand, but it does not guarantee a profitable day.
Rising confidenceYour recent results are giving the stand a stronger demand signal. Use it, but still respect price and production cost.
Low confidenceDo not try to fix everything by spending more at once. Stabilize the stand with smaller, easier-to-read experiments.
After closing
How to read the day report
The report is your main learning tool. Do not judge a day only by revenue; compare sales with the money you committed to production and promotion.
- Sold / preparedShows whether you stocked too little, too much, or roughly enough.
- RevenueMoney collected from customers before expenses.
- Production costWhat you spent preparing glasses, including glasses that did not sell.
- Advertising costWhat you spent on signs before knowing the day’s final demand.
- Profit or lossThe clearest measure of whether the day’s combination of inventory, promotion, and price worked.
- Ending assetsYour ability to fund the next day and grow toward a larger stand.
If you sold out
You may have left sales on the table. Next time, consider preparing more—but only if the added production cost still makes sense for similar conditions.
If many cups were left
You probably overproduced for the demand you created. Try less inventory, a lower price, more advertising, or a combination—but change deliberately so you can tell what helped.
Growing the stand
Success gives you more room to operate
Your operating balance controls the scale of the stand. As it grows, the game raises the maximum number of glasses, signs, and price you can choose. Falling back below a threshold can reduce that capacity again.
Neighborhood stand
Below $100, you can prepare up to 15 glasses, use up to 3 signs, and charge up to $2.99.
Growing business
At $100 and $500, larger operating ranges unlock. More capacity creates more upside—but also makes expensive mistakes possible.
Established stand
At $5,000 and above, the largest operating range becomes available. Later finance systems can also add fees, taxes, banking, credit, and interest around the same three daily decisions.
Starter tactics
Make the game readable
The fastest way to improve is not to chase a perfect formula. Make controlled changes, watch the report, and learn how each condition changes the result.
Protect your cash
Production and advertising are paid before the day resolves. Keep enough balance to survive a bad forecast or a poor experiment.
Change one big thing at a time
If you radically change glasses, signs, and price together, the report cannot tell you which change mattered most.
Use sell-outs as information
Selling every glass is not automatically optimal, but repeated sell-outs in similar conditions suggest your inventory ceiling is constraining sales.
Use leftovers as information
Unsold glasses mean you paid for capacity the market did not use. Compare leftovers with price, advertising, weather, and confidence before the next day.
Price is not just profit
A higher price increases revenue per sale while reducing demand. Watch total profit, not just the price tag.
Let conditions change your plan
The same setup should not be repeated automatically every day. Weather and confidence are there to make yesterday’s answer uncertain today.
Behind the game
The math is part of the fun
You never need the equation to play well, but it explains why signs, confidence, price, and weather can combine into surprisingly different days.
The demand equation used by this version
((signs² / log1p(signs) + confidenceRoll × confidence) / priceDollars) × (weatherVariant² + 1)
The result is rounded to a whole number of potential customers, then actual sales are capped by the number of glasses you prepared. In other words: advertising and confidence push demand upward, price pushes it downward, weather can amplify everything, and inventory still sets the final ceiling.
A useful curiosity: advertising is deliberately nonlinear here. The sign term is signs² / log1p(signs), so signs can become very powerful instead of following a simple diminishing-return curve.
Then and now
How the Apple II game differs
The modern game keeps the original spirit—three decisions, weather, uncertainty, and immediate consequences—but it does not copy the Apple II economics exactly.
| System | Apple II version | This Lemonade revival |
|---|---|---|
| Price | Used a 10-cent reference price and a much steeper inverse-square penalty above it. | Price enters continuously as an inverse term. There is no special breakpoint where the rules suddenly change. |
| Advertising | Used an exponential response with diminishing returns. | Uses the unusual signs² / log1p(signs) term, so advertising behaves very differently and can scale aggressively. |
| Demand base | Started from a baseline demand of 30 before price, signs, weather, and events changed it. | Builds potential demand from advertising plus confidence, divided by price, then multiplied by weather. |
| Confidence | Not the same persistent operating-confidence system used here. | Recent business performance changes confidence, and a seeded daily confidence roll feeds demand. |
| Weather | Weather and special events changed demand through the original BASIC rules. | Uses four weather strengths—1×, 2×, 5×, and 10×—with the opening day starting at the strongest state. |
| Randomness | Used the period program's random draws. | Uses seeded randomness, so the same starting seed and decisions can reproduce a run. |
| Presentation | Text, simple color graphics, sound cues, and keyboard interaction on the Apple II. | A live 3D Lemonsville, visible customers and signs, accessible reports, charts, progression, and later finance systems around the same three daily choices. |
Where the game came from
A classroom business game with a long life
Lemonade keeps the quick decision-and-feedback spirit of the educational games that came before it. The history is here for players who want to know why the game is deliberately simple to learn and difficult to optimize.
1973
Bob Jamison and MECC
Bob Jamison created the original Lemonade Stand program at the Minnesota Educational Computing Consortium for time-shared computer systems.
1979
Apple II adaptation
Charlie Kellner adapted the program for the Apple II, bringing the business exercise into the early personal-computer classroom.
1980s
Computer-lab learning
Apple II computers became familiar school lab machines, where students learned by trying software, comparing results, and taking turns around shared screens.
Today
Lemonade
The modern revival keeps the small daily decision surface while making the neighborhood, customers, weather, reports, and progression visible around it.
Historical references
About the original game
These links support the historical section. They are optional reading and are not required to understand or play Lemonade.