Buy a Smart Oil Gauge
Two questions tell you which gauge fits your tank and exactly which adapter, if any, you need. Everything ships free from Danbury, Connecticut, with a 2-year warranty and 90 days to change your mind.
Start here: what fits your tank?
Most tanks take a gauge straight onto a spare 2″ NPT fitting. If yours needs an adapter, it has to match the model — the Duo's and the Original's are different parts. Answer two questions and we'll put the right gauge, and an adapter only if you need one, in your cart together.
Two questions and we'll pair it for you.
Steel tanks: above ground only, 138 to 550 gallon, vertical or horizontal, single or side-by-side. Roth double-wall tanks: the 400L, 620L, 1000L and 1000LH all work with the Roth adapter.
Find the spare fitting on top of your tank — not the fill pipe, not the vent. Measure straight across the outside of that plug, edge to edge. A tape measure is fine; you don't need to be exact to the sixteenth.
Measured something else? Send us a photo and we'll identify it for you.
The size is stamped on the label on the front of the tank. Every Roth needs our Roth adapter.
Or pick your gauge.
If you already know your tank has a standard 2″ NPT fitting — the most common one — no adapter is needed and you can order straight from here.
Smart Oil Gauge Duo
- Dual ultrasonic sensors that read all the way to the top of the tank
- Accurate right after a delivery — a topped-off tank reads correctly instead of stopping at 235
- Fits 2″ NPT (most common), 1.5″ adapter, and Roth tanks
Smart Oil Gauge
- Everything most homeowners need — remote monitoring, low-level alerts, usage history, Alexa
- The widest fit — the only model that works with a 1.25″ NPT adapter
- One ultrasonic sensor, which starts reading a few inches below the top of the tank
Never installed. May have a fingerprint or two. Ships with the latest firmware and a fresh set of batteries, and carries a one-year warranty instead of two. Indoor use only.
Only if your tank needs one.
Most tanks have a spare 2″ NPT fitting and need no adapter at all. If yours doesn't, buy the adapter that matches your gauge — they are not interchangeable.
1.5″ NPT adapterFor tanks with a 1.5″ fitting instead of 2″
Photo & details
$37.50
DuoUse this when a Duo is going into a non-standard 1.5″ opening. An internal guide cone keeps the sensor's sound wave clear of the adapter walls on its way down to the oil. An off-the-shelf reducer from a hardware store causes interference and the gauge will not read.
Roth adapterFor Roth 400L, 620L, 1000L and 1000LH
Photo & details
$37.50
DuoThreads onto the Roth fitting first; the Duo then hand-tightens into the adapter and the whole assembly lowers onto the tank.
1.5″ NPT adapter CCF-905For tanks with a 1.5″ fitting instead of 2″
Photo & details
$37.50
OriginalUse this when the Original is going into a smaller 1.5″ NPT opening. The internal guide cone keeps the sound wave from the sensor clear of the adapter walls. Off-the-shelf reducers cause interference and the gauge will not work.
1.25″ NPT adapter CCF-908The Duo does not fit a 1.25″ opening — this pairs with the Original only
Photo & details
$37.50
OriginalThe least common fitting size, so measure your opening before ordering. It threads directly into one of the four openings on top of the tank.
Roth adapter CCF-906For Roth 400L, 620L, 1000L and 1000LH
Photo & details
$37.50
OriginalThreads onto the Roth fitting, and the Smart Oil Gauge threads into the adapter.
Replacement batteries, 2-pack CCF-907Two SAFT LS14500 lithium 3.6V AA cells — the same ones your gauge shipped with
Photo & details
$16.00
BothA set typically lasts one to three years. The app shows the battery level, and we usually recommend ordering a fresh set when it displays Fair or Poor.
If it isn't right, send it back.
We would rather take a gauge back than have it sit unused on a shelf. Buying direct is the only way to get these terms.
Returns
Return a new gauge within 90 days of purchase for a full refund. That's most of a heating season — long enough to see it work through a cold snap and a delivery before you commit.
Email support@smartoilgauge.com to start a return and we'll send you instructions. Adapters and accessories come back under the same window.
Warranty
Every new gauge bought on this site carries a two-year replacement warranty from the date of purchase. If it fails, we replace it.
Refurbished gauges carry a one-year replacement warranty. They are never-installed units with the latest firmware and fresh batteries — the shorter term is the trade for the lower price.
Before you order
How do I know it will fit?
Measure the spare plug on top of your tank, straight across the outside. Most are 2″ NPT and need nothing else. The fit finder walks you through it in two questions, and if you're still not sure, send us a photo and we'll identify it.
Do I need an adapter?
Only if your fitting isn't 2″ NPT, or if you have a Roth double-wall tank. When you do, it has to be the adapter made for your model — Duo adapters and Original adapters are different parts.
Will it work on a Roth?
Yes, on the 400L, 620L, 1000L and 1000LH, with the Roth adapter for your model. The Roth 1500L has internal baffles that block the ultrasonic signal, so neither gauge can read it reliably and we don't sell one for it.
What if it doesn't work out?
Send it back within 90 days. Every new gauge bought here carries a 2-year warranty; refurbished units carry one year.
How fast does it ship?
Order by 1pm Eastern on a business day and it goes out that day. After that, it ships the next business day. Shipping is free either way.
What's in the box?
The gauge, batteries and instructions — everything you need for the install. Nothing else to buy unless your tank needs an adapter.
How long do the batteries last?
One to three years on a set. It takes two SAFT LS14500 lithium 3.6V AA cells, and the app shows the battery level — we usually recommend ordering a fresh set when it displays Fair or Poor. Spares are $16 above.
How hard is the install?
Most people are done in a few minutes: take out the spare plug on top of the tank, apply a little pipe dope, thread the gauge in with a pipe wrench, and connect it to your Wi-Fi. Nothing touches the fuel line.