Spin-to-Win Prize Tables: Odds, Caps and Cost
Set spin-to-win odds, stock, per-person limits and a campaign budget together, then work out the worst-case cost before launch.
A spin to win prize table stays inside budget when four controls work together: the odds on each slice, a stock count for each prize, a limit per person and a campaign budget you have checked against the worst case. Odds describe an average run, not a bad one. This guide shows how to set each control, do the cost sum before launch and keep the evidence a UK promoter needs. The method works on any tool, and Portico Play's committed tables are the example of how it looks in practice.
- Short answer: Set odds, per-prize stock, a per-person limit and a budget together, then work out both the expected and the worst-case cost before the first spin.
- First step: List every prize with what it costs you, its probability and how many you can afford to give away.
- The goal: A table you could defend to finance and to a regulator, with a worst-case figure you have already signed off.
Tips: Do the worst-case sum before you design the wheel, not after. If the ceiling makes you wince, the table is wrong, and it is far cheaper to find that out on paper.
Key takeaways
A spin-to-win prize table stays inside budget only when odds, per-prize stock, a per-person limit and a campaign budget work together, and when you have calculated the worst-case and expected cost and committed the table before the first spin.
| Point | Detail |
|---|---|
| Odds are not a budget | A percentage against each slice describes what should happen on average, so it cannot stop a 20% prize landing several times in a row. |
| Cost has two numbers | Work out the expected cost to plan with and the worst-case cost to sign off, because the worst case is the figure your finance team will ask about. |
| Commit before you spin | A table fixed and recorded before the first spin, with limited prizes set aside for the session that drew them, is easy to defend and hard to overspend. |
| Fairness is evidence | A UK promoter should be able to show random selection, honest odds, an immediate result and no cost to claim, so have the proof of each ready before launch. |
Contents
- What does a spin-to-win prize table need besides odds?
- How do I work out the worst-case and expected cost of a wheel?
- How many of each prize should I hold in stock, and what happens when one runs out?
- How do I stop one person winning again and again?
- Should I fix the prize table before the first spin?
- What does a UK promoter have to show for an instant-win wheel?
- Frequently asked questions
- Sources
What does a spin-to-win prize table need besides odds?
A spin-to-win prize table needs four controls: odds, a stock count for each prize, a limit per person and a campaign budget. Odds say how likely each slice is. The other three say what you will actually pay when luck does not behave. A table with only the first leaves your cost to chance.
Most guides to wheel setup stop at typing a percentage against each slice. That is the easy part, and it hides the problem. Every spin is independent, so the wheel has no memory of what it paid out a minute ago. A prize with a 20% chance can land several times in a row, which is why probability percentages alone should not be what controls cost.
Think of the four controls as four different questions:
| Control | The question it answers | What it cannot do alone |
|---|---|---|
| Odds | How often should each slice come up on average? | Stop a prize landing more often than average. |
| Per-prize stock | How many of this prize can exist at all? | Stop one person taking several of them. |
| Per-person limit | How many times can one person play or win? | Limit the total number of prizes given. |
| Campaign budget | What is the most this campaign may cost? | Tell you which prize to run out of first. |
Each control covers a gap in another. Stock puts a hard ceiling on a prize, however the odds fall. A per-person limit stops a single enthusiast draining that stock. The budget is the number you test the whole table against, and it is usually the one finance will ask about first.
The rest of this article sets the controls in the order you would work: the cost sum, the stock, the person limit, committing the table, and the evidence a UK promoter keeps. If you want a wheel to look at while you read, the Welcome Wheel demo plays with made-up DEMO- codes, so you can spin it without costing anyone anything.
How do I work out the worst-case and expected cost of a wheel?
Multiply each prize's cost by its probability to get the expected cost per spin, scale that by the spins you expect, then multiply each prize's stock by its cost to get the ceiling. You need both numbers. The expected cost is what you plan around, and the worst case is what you sign off.
Follow these steps in a spreadsheet:
- List each prize with its cost to you. Use what the prize costs the business, not the retail value. A free coffee that costs you £1.50 to make is £1.50.
- Write the probability against each prize. The probabilities, including the no-win slice, must add up to 100%.
- Multiply cost by probability. The sum of those results is the expected cost of one spin.
- Multiply by expected spins. That is the expected total, the figure to plan the budget around.
- Multiply each prize's stock by its cost and add them up. That is the worst case with stock limits in place.
- Compare with what happens with no stock limits. Spins multiplied by your most expensive prize is the true worst case of a table with no caps.
Here is a fictional example, not a customer: a café group plans a wheel for 4,000 spins.
| Prize | Cost to us | Probability | Stock |
|---|---|---|---|
| Free coffee | £1.50 | 10% | 500 |
| Free pastry | £2.50 | 5% | 250 |
| £10 voucher | £10.00 | 1% | 50 |
| Better luck next time | £0 | 84% | no limit |
The expected cost per spin is 0.10 × £1.50 + 0.05 × £2.50 + 0.01 × £10, which is £0.375. Across 4,000 spins that is £1,500. The ceiling is £750 + £625 + £500, which is £1,875. Without stock limits, 4,000 spins at the £10 voucher would be £40,000. The gap between £1,875 and £40,000 is the work stock does.
Tips: Run the sum a second time with double your spin forecast. If the ceiling still holds, a campaign that goes better than planned stays inside budget too.
Be honest about scale. If every prize costs pennies, such as a small discount code that only costs you when redeemed, you need little more than a stock count and a quick check. The full sum earns its keep once a single prize is worth real money.
Prize cost is also separate from the platform fee, which is a different line in your budget. Plans are on the Portico Play pricing page.
How many of each prize should I hold in stock, and what happens when one runs out?
Stock is the real cap on a prize, whatever the odds say. Size it from your expected number of wins plus a margin you are happy to pay for, set a fallback outcome for when a prize is gone, and make the stock a real number rather than a promise. A prize that has run out cannot be won, so its cost stops there.
Low odds do not cap cost, only stock does.
That is the point most easily overlooked. A 1% prize feels safe, but across enough spins it will be won, and sometimes early.
Work through stock like this:
- Start from expected wins. Using the café example, 4,000 spins at 1% gives about 40 vouchers, so 50 in stock leaves a margin of 10. Choose the margin by asking what you would pay if luck ran hot.
- Size expensive prizes tightly. A small stock on the top prize is cheap insurance. Generous stock on cheap prizes costs little and keeps the wheel feeling alive.
- Decide the fallback before launch. When a prize is gone, the wheel needs somewhere to land: a smaller prize or the no-win outcome. Say in your terms which it is, so nobody is surprised.
- Keep the stock a real number. Prizes delivered as codes are easiest to count, because the pool is the stock. Portico generates codes in a format that avoids easily confused characters, such as 0, O, 1, I and L, so a code read over the phone or typed from a screenshot is not misread.
- Back codes with your own checkout where you can. Through the Shopify connector, a code pool can be backed by one Shopify discount, with the codes created in Shopify before anyone is handed one. A brand sets the connector up before its players see it. See the integrations page for what it connects to.
- Plan for prizes a person must hand over. Manual deliveries, shipping and codes that ran out can land in a fulfilment queue, with an owner and a note, so a shortfall is a task and not a complaint.
For a shop or store group, the retail solutions page describes shelf cards, bags, receipts and newsletters leading to codes. The point to carry away is that stock should be a number your team can count on a Monday morning.
How do I stop one person winning again and again?
Set a per-person limit by choosing how often one person may play, then decide how strongly you can identify them. A limit of one spin in total, one a day or a cap on wins each suits a different campaign, and the strength of the limit depends on how you recognise the person.
| Limit | Best for | Weak point |
|---|---|---|
| One spin in total | A welcome offer or a launch giveaway | Someone who can present as a new person gets another turn. |
| One spin a day | A calendar or a loyalty routine that brings people back | Costs add up over the window, so budget for the number of days. |
| A cap on wins | A wheel with several plays where you want to share prizes widely | A rule you set in the terms; the simplest way to enforce it is to limit plays. |
Identity is the real question. In Portico's event limits, the participant is the signed-in player where the session has one, and otherwise the device, identified by a hash of the user agent, platform hint and primary language. The device route is best effort: a different phone or browser counts as a new participant, and a browser update can change the hash. On an anonymous wheel, a limit is a deterrent, not a guarantee.
A verified participant is a stronger identity. A player verifies their email with a six-digit code and is recognised again on the same brand's campaigns, never across brands. The price is friction: asking for an email and a code before a spin loses some people. Choose by the value of the top prize. A wheel giving away a £1.50 coffee can live with a best-effort limit. A wheel with a £500 prize should ask who is spinning.
Daily limits follow the clock of the campaign, not the server. A campaign has its own time zone, its days turn at midnight there and not in UTC, and a new campaign starts in the organisation's zone. A "once a day" wheel for a London café therefore resets at London midnight. A campaign with no zone set keeps UTC, so check yours before launch.
For ideas on bringing people back day after day without handing out a prize every time, see the retention and loyalty page.
Should I fix the prize table before the first spin?
Yes. Commit the whole table, meaning the prizes, the odds and the stock, before any spin, and do not change it while the campaign runs. A fixed table is the easiest to defend, because nobody can say the odds moved after a big win. It also fits the regulator's advice on keeping terms steady and keeping evidence.
The ASA and CAP's advice on prize draws says promoters need evidence that selection was fair and random, with an independent observer if no verifiably random computer process is used. It says significant conditions must be stated up front and that changing terms mid-promotion should be avoided. That advice is written for prize draws, and an instant-win wheel is a different mechanic, but the habits carry over: write the rules down first, keep proof and leave the terms alone.
Portico builds this into the mechanism. A table of outcomes and odds is committed before the draw, so the result a player sees was fixed against a table that already existed. A limited prize is set aside for the session that drew it before its table is committed, which means the prize that player won is held for them and cannot also be given to someone else. Together those two steps make the table hard to overspend and the result easy to explain afterwards. The fairness page describes how rewards are verified.
Tips: Play the finished campaign in preview before launch. Preview lets you play a draft exactly as a participant would, without spending, sending or counting anything, so a wrong stock number costs you nothing.
Sometimes the table has to change anyway. A prize supplier drops out, or a figure was wrong. When that happens, version the change and record it instead of editing the live table silently. Changes to a published Portico campaign are held as a draft until you publish them, you can see exactly what changed, and you can go back to an earlier version. Anyone asking what the odds were on a given day can then be answered with a record. If a change affects what entrants were promised, update the terms at the same time and say so.
What does a UK promoter have to show for an instant-win wheel?
A UK promoter should be able to show four things: winners picked fairly and randomly, a chance of winning that is not exaggerated, a result and claim route shown at once, and nothing to pay to claim. The ASA and CAP's advice on instant wins sets these out. Treat it as guidance, and check your own terms with a legal adviser.
Use this as a pre-launch checklist:
- Random and provable. Winners must be selected fairly and randomly, and you must be able to show it. Keep the committed table and the record of results together, so you can answer a complaint with evidence instead of memory.
- Honest chance. Promoters must not exaggerate the chance of winning. If the top prize is 1%, do not build the creative around it. Show the realistic odds in the terms and keep the wheel's artwork from implying more than the table delivers.
- Immediate result. Winners must know straight away what they have won and how to claim it. The spin should end on a screen that names the prize and says what happens next.
- Nothing to pay. There must be no cost to claim. Do not ask for postage, a purchase or a paid call to collect a prize.
- No form before the result. Calling a promotion instant-win can be misleading if the entrant has to fill in a form to learn the result. Show the outcome first, and ask for details afterwards if you need them.
Each item ties back to a control earlier in this article. Random selection and evidence come from committing the table. Honest chance comes from the odds and the cost sum, which show you what the wheel really does. The immediate result and free claim depend on stock that exists, so a prize shown is a prize you can deliver. The person limit stops the table being gamed.
Your first action is the sum from earlier: build the table in a spreadsheet, work out the expected cost and the ceiling, and sign off the worst-case figure. If you would rather not start from blank, the campaign templates start you from a prepared game, rules, look and prize placeholders as a draft that goes live once real rewards are in.
Frequently asked questions
What odds should I set on a spin-to-win wheel? Set them from what you can afford, not from what feels generous. Put a number on each prize's cost, choose probabilities that give an expected cost per spin you are happy with, and check that stock covers the worst case. Keep the top prize rare and say honestly how rare it is.
Can a spin-to-win wheel go over budget? Yes, if odds are the only control. Each spin is independent, so an expensive prize can land several times in a row. Per-prize stock puts a ceiling on each prize, and multiplying stock by cost shows the most the wheel can pay out.
How do I calculate the expected cost of a prize wheel? Multiply each prize's cost by its probability and add the results to get the cost per spin. Multiply by the number of spins you expect. Then work out the worst case separately from stock multiplied by cost.
Do I need a no-win slice on the wheel? Not always, but most budgets need one. A no-win outcome carries no cost and lets you keep the odds on real prizes low enough to afford. If you would rather everyone won something, make the smallest prize genuinely cheap and cost the table on that basis.
Is a spin-to-win wheel legal in the UK? Instant-win promotions are a recognised type, and the ASA and CAP publish advice on running them. They expect fair and random selection that you can prove, honest descriptions of the chance of winning, an immediate result and no cost to claim. Check your final terms with a legal adviser.
Sources
- ASA/CAP advice: Promotional marketing, instant wins
- ASA/CAP advice: Promotional marketing, prize draws