SmartInsulationCalculator

Water Heater Blanket Calculator

A blanket on an older tank pays for itself in a season. Enter your tank size for blanket dimensions, cost and expected savings.

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Prices as of Oct 11, 2026, 4:41 AM UTC. Product prices and availability are accurate as of the date/time indicated and are subject to change. Any price and availability information displayed on Amazon.com at the time of purchase will apply to the purchase of this product.

How this calculator works

  • Blanket width = π × tank diameter
  • Surface area = circumference × tank height
  • Savings ≈ water heating share of the bill × 3–5%

Frequently asked questions

Can you put a blanket on a gas water heater?

Yes, but never cover the top, the burner access, the thermostat, the pressure relief valve or the flue. Electric tanks can be wrapped everywhere except the controls.

Do new water heaters need a blanket?

Usually not — anything made in the last decade already has R-16 or better foam. Touch the side of the tank: if it feels warm, a blanket helps.

Is a water heater blanket worth it?

On an older tank that feels warm to the touch, yes — that warmth is standby loss you are paying for continuously. On a modern well-insulated tank the gain is much smaller, because the manufacturer already did most of it. Touch the side of the tank: if it is noticeably warm, a blanket has something to work with.

Can you put a blanket on a gas water heater?

With real care, and some manufacturers prohibit it outright. A gas heater draws combustion air at the bottom and vents at the top, and covering either is genuinely dangerous. The top, the burner access, the thermostat, the pressure relief valve and the drain must all stay clear. If in doubt on a gas unit, do not.

Should I insulate the pipes at the same time?

Yes — the first few feet of hot outlet pipe carries heat away continuously through convection, and it is cheap to cover. Doing the tank and leaving bare pipe out of the top is a common half-job that gives up a meaningful share of the benefit.

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Blanket size needed

5.2 ft × 5 ft

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