The balloon is the cheap part. Nobody tells you that before you buy one. A helium advertising balloon has a purchase price you pay once and a gas bill you pay forever. If you only budget the first one, the second one arrives as an unpleasant surprise around week three. This page is the gas bill, in detail.
The unit cost of helium
Helium from a local welding-gas supplier runs about **$300 for a 200 cubic foot tank**. That works out to **$1.50 per cubic foot**, and that is the number every calculation below is built on.
Welding-gas suppliers, not party stores. Party-grade helium is sold in small quantities at many times the price, and it is not the right source for a balloon that needs 170 cubic feet at a time.
What each size drinks
**5.5-foot sphere** — about 87 cubic feet for a full fill. At $1.50 per cubic foot, roughly **$130**.
**13-foot blimp** — about 170 cubic feet for a full fill. Roughly **$255**.
So one 200 cubic foot tank fills a sphere twice with gas to spare, or fills a blimp once with a little left for a top-off. That is the practical planning unit.
The one percent rule
Every helium balloon loses roughly **one percent of its gas per day**.
This is not a leak and not a defect. Helium is a very small molecule and it migrates through any flexible material given time. Every balloon, from every manufacturer, everywhere, does this.
What it means in practice: top off every **three to seven days**. On a blimp that is about **$2.50 per day of flying**. On a sphere it is a fraction of that.
Do the arithmetic on a sphere and it is genuinely cheap: one 200 cubic foot tank covers about **two months** of flying, including top-offs.
Why the one percent figure is good news for events
Run the numbers on a three-day trade show and the picture changes completely.
One percent per day over three days is three percent. A blimp filled on Monday is still at ninety-seven percent on Wednesday evening. That means **one fill covers a typical three-day show** with room to spare.
No helium on site. No tank in the booth. No refill scheduled into an already tight show day. You fill before you go and you are done.
The same logic covers a weekend sale, a grand opening, or a two-day event.
Budgeting a season
Say you fly a blimp every weekend, Saturday and Sunday, and bring it in during the week.
Your first fill is $255. After that you are topping up what a couple of days of exposure cost, which lands around $2.50 per flying day. Twenty weekends of flying is forty flying days — roughly $100 of top-offs across the season, plus your initial fill and any re-fill after a full deflation.
If instead you fly continuously, the top-off cycle runs every three to seven days year-round, which is where the $2.50 per day figure does most of its work.
Either way, the annual helium bill on one blimp is a few hundred dollars, not a few thousand. It is a real cost and a manageable one.
Equipment you need
A **fill hose** — $45 as a one-time add-on if you do not already have one.
A **tank**, from your local supplier. Most suppliers rent or exchange cylinders rather than selling them outright, so ask about the cylinder deposit or rental separately from the gas price.
Nothing else. There is no regulator kit or specialist gear beyond what the supplier provides with the cylinder.
Things that quietly cost you helium
**Wind.** Not because it damages the balloon, but because a windy day means more handling, more time on the fill, and — in the worst case — a balloon that gets away entirely. The rule is 25 miles per hour forecast, bring it in.
**Heat.** Hot air is thinner, so lift drops on very hot days even at the same fill level. This reads as “the balloon seems low” and gets answered with gas.
**Repeated deflation and re-inflation.** Every full cycle costs a full fill. If you are flying most weekends, leaving it inflated and topping off is cheaper than emptying it every Sunday night.
What you get for the money
A 13-foot advertising blimp is $1,526 with full-colour artwork on both sides included, plus $135 shipping. A 5.5-foot sphere is $350 plus $27. Both ship UPS Ground from North Carolina in two to five business days, in a single carton.
Both fly at 120 feet, deliberately below the 150-foot line at which the FAA becomes involved in tethered balloons. Within five miles of controlled airspace, call the local tower first.
If the gas logistics are the objection
In greater Phoenix and Tucson there is a service option where helium is simply not your problem — the equipment, gas, setup, weather watching and removal are all handled. Balloon service is $247.25 per day in greater Phoenix and $277.25 in Tucson; blimp service is $297.25 and $327.25.
Weekend-priced, billed the Monday after, no contract and no minimum. If weather keeps it down, there is no charge for that day.
Questions we get
What does a 13 ft advertising blimp cost?
$1,526 printed, with full-colour artwork on both sides included in the price. Shipping is $135 UPS Ground from the factory in North Carolina.
How much helium does it use?
About 170 cubic feet for a full fill, roughly $255 at $1.50 per cubic foot from a welding-gas supplier. It loses about one percent per day, so top off every three to seven days.
How high does it fly?
120 feet on the standard tether. That is deliberately below the 150-foot line at which the FAA becomes involved in tethered balloons.
What happens in wind?
Winds forecast over 25 miles per hour, bring it in. Wind does not wear a balloon out, but it can lose one.
How long until it ships?
Three to seven days from artwork approval, plus two to five business days shipping.
More at marketingballoons.com.