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Tilt vs RAPT Pill vs iSpindel: digital hydrometers compared

Three floating sensors that log gravity and temperature from inside the fermenter. They differ in power, connection and how much setup you do yourself.

Updated November 2026 · 6 min read

A thick tan krausen foam on top of fermenting beer in a bucket
Tilt Wireless Hydrometer & Thermometer (Black)Tilt Wireless Hydrometer & Thermometer (Red)Tilt Pro Mini Wireless Hydrometer & Thermometer (Black)Tilt Pro Wireless Hydrometer & Thermometer (Black)Tilt Pico Wi-Fi Bridge for Tilt HydrometersKegLand RAPT Pill Digital Hydrometer & Thermometer (Red)
Photo: Phillie Casablanca, CC BY 2.0, via Flickr
The short version
  • Tilt (standard): SG 0.990–1.120, ±0.002 SG and ±1°F per Tilt, Bluetooth to a phone, tablet or Tilt Pi, and a CR123A battery rated 12–24 months. The Tilt Pico bridge adds Wi-Fi cloud logging.
  • RAPT Pill (KegLand): ±0.002 SG and ±0.2°C (0.36°F), Wi-Fi straight to the RAPT portal or Bluetooth to a RAPT host, USB-C rechargeable 18650 cell, rated 0–5 bar for pressure fermenters.
  • iSpindel is an open-source Wi-Fi hydrometer you build and calibrate yourself; there's no branded listing in our catalogue.
  • All three estimate gravity from the tilt angle of a floating body, so check them against a hydrometer at the start and end.

Tilt vs RAPT Pill is the comparison for brewers who want a fermentation curve without pulling samples. Both are sealed floats that sit in the beer and measure their own angle and temperature; as sugar turns to alcohol, the liquid gets less dense, the float tips and the app converts that angle to specific gravity. The iSpindel, an open-source project, does the same over Wi-Fi if you're willing to build one.

We compared the listed and maker specs of each: Tilt's listings and spec sheet, KegLand's RAPT Pill product page, and the iSpindel project documentation. Browse every meter in the hydrometers and meters hub, and see hydrometer vs refractometer for the manual tools you'll still use to check them.

Tilt

Bluetooth, CR123A battery for 12–24 months, ±0.002 SG; one color per fermenter

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vs

KegLand

RAPT Pill: Wi-Fi or Bluetooth, rechargeable 18650 cell, ±0.002 SG

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Picks from each side

Tilt

KegLand

Tilt vs RAPT Pill vs iSpindel: the spec table

Listed and maker specs

Tilt (standard)Tilt Pro MiniRAPT PilliSpindel (DIY)
SG range0.990–1.1200.9900–1.1200, user-calibratable to 1.2000Not stated on the listingDepends on your calibration
SG accuracy±0.002 (Tilt)±0.002; 0.0001 resolution (Tilt)±0.002 (KegLand)Depends on calibration
Temperature accuracy±1°F (±0.5°C)±1°F (±0.5°C)±0.2°C (0.36°F)Sensor-dependent
ConnectionBluetooth to app or Tilt Pi; Wi-Fi via Tilt PicoBluetoothWi-Fi, or Bluetooth to a RAPT hostWi-Fi
BatteryCR123A, 12–24 months (Tilt)CR123ARechargeable 18650 via USB-CUsually an 18650 you fit
SizeNot listed29 × 115 mm; fits a 1.5 in. tri-clamp portAbout 37 × 125 mmBuilt into a PET tube
Pressure useNot listedSized for kegs and pressure fermentersRated 0–5 bar (KegLand)Depends on build
Multiple fermentersOne color per fermenterOne color per fermenterEach Pill has its own IDEach unit has its own ID
In our catalogue✓✓✓✗ DIY

Source: Tilt listings and spec sheet; KegLand RAPT Pill product page; iSpindel project

Tilt Pro specs vary between sources: the listing claims 0.0001 SG accuracy and sizing for commercial tanks up to 20 BBL, while retailer spec pages give two AA lithium cells and a 0–140°F range. Treat the Pro as a commercial-tank tool and check Tilt's current sheet before buying it for a homebrew fermenter.

Battery life and charging

Battery life, low end of the maker figure

Months between battery changes or charges

Tilt (CR123A, 12–24 mo)Tilt (CR123A, 12–24 mo): 12 mo12 moRAPT Pill on Bluetooth, 60 min intervalRAPT Pill on Bluetooth, 60 min interval: 12 mo12 moRAPT Pill on Wi-Fi (2–5 mo)RAPT Pill on Wi-Fi (2–5 mo): 2 mo2 mo
Source: Tilt listing; KegLand RAPT Pill listings (figures vary with telemetry interval)

The Tilt runs on a replaceable CR123A for 12–24 months per Tilt, depending on use. The RAPT Pill uses a rechargeable 18650 cell over USB-C (or an optional wireless charging kit); KegLand quotes about 12 months on Bluetooth at a 60-minute reporting interval and roughly 2–5 months on Wi-Fi. Wi-Fi is convenient because the Pill talks to the RAPT portal directly, but it drains the battery faster. KegLand advises charging for 24 hours before first use.

Bluetooth vs Wi-Fi: how the data reaches you

  • Tilt: broadcasts over Bluetooth to the Tilt app on a phone or tablet nearby, or to a Tilt Pi (a Raspberry Pi image). The Tilt Pico (B0G4HYJ212) is a Bluetooth-to-Wi-Fi bridge that logs to the cloud, handles several Tilts and stores about two months of data.
  • RAPT Pill: connects over Wi-Fi to the RAPT portal and app on its own, or over Bluetooth to a RAPT host such as a RAPT temperature controller, fermentation chamber or the BrewZilla Gen 4 Wi-Fi model.
  • iSpindel: sends Wi-Fi data to a service you configure (several free brewing platforms accept it).

Stainless fermenters and kegs block radio signals. Tilt markets the Pro Mini for kegs and stainless, and the Pico for better range around steel; with a RAPT Pill, a host or Wi-Fi access point close to the vessel helps. Fridges and chest freezers also block signals, so plan the bridge outside or near the door seal.

How accurate are floating hydrometers?

±0.002 SGTilt and RAPT Pill, per maker
±0.2°CRAPT Pill temperature accuracy (KegLand)
±1°FTilt temperature accuracy (Tilt)
A glass hydrometer with scale on a white background
A classic hydrometer is still the reference.Photo: Jacek Halicki, CC BY-SA 4.0, via Wikimedia Commons

A ±0.002 SG accuracy means a reading of 1.012 could be 1.010–1.014. That's fine for watching a fermentation curve and spotting when it stops, but confirm original and final gravity with a hydrometer before you calculate ABV with the ABV calculator or bottle. KegLand notes that solids stuck to the outside of the Pill can affect accuracy; heavy krausen or fruit additions do the same to any float. Recalibrate in plain water when readings drift.

Avoid bottle bombsBottle only after the gravity reads the same 2–3 days in a row, measure priming sugar with a calculator, use standard bottles only to about 3 volumes, store them in a closed box at room temperature and refrigerate once carbonated.Source: BYO carbonation priming chart

Who should choose which

Pick by setup

Your setupTiltRAPT PilliSpindel
Phone nearby, no extra gear✓ Bluetooth app✓ Wi-Fi~ Needs a server or service
Several fermenters at once✓ Different colors✓✓
Already own RAPT or BrewZilla Wi-Fi gear~✓~
Pressure fermenter or keg✓ Pro Mini✓ 0–5 bar rating~
Hate charging devices✓ 12–24 mo battery~ Recharge~
Like building and coding✗✗✓
Inside a fridge or chest freezer~ Add the Pico~ Host nearby~

Choose a Tilt if you want a long-lasting replaceable battery, a simple Bluetooth app and the option of a Pro Mini for kegs. Choose the RAPT Pill if you want built-in Wi-Fi, a better listed temperature accuracy, a rechargeable battery and integration with KegLand's RAPT controllers and BrewZilla. Choose an iSpindel only if you enjoy DIY electronics. Pair any of them with a temperature controller from the temperature control page.

Mistakes to avoid

  1. Trusting the float without a reference reading. Check against a hydrometer at pitching and before packaging.
  2. Dropping it in unsanitized. Sanitize the float at label dilution like any other cold-side gear.
  3. Using two Tilts of the same color in one app. Each color is one channel; the Pico can separate same-color Tilts by hardware address.
  4. Leaving the RAPT Pill on a short Wi-Fi interval. A 15-minute interval drains the battery fastest; 60 minutes is enough for most fermentations.
  5. Expecting signals through stainless. Use a bridge or host near the vessel.
  6. Forgetting to log. Export or copy readings into the brew-day log so the batch record stays complete.
Verdict

Tilt is the easy, long-battery choice for Bluetooth logging, with the Pro Mini for kegs and a Pico bridge for Wi-Fi. KegLand RAPT Pill is the pick for built-in Wi-Fi, tighter listed temperature accuracy, a rechargeable cell and RAPT integration. Both list ±0.002 SG, so treat either as a trend tool and confirm gravity with a hydrometer. The iSpindel is for DIY fans only.

How we chose

We compared the specs on the Tilt listings and spec sheet, KegLand's RAPT Pill product pages, and the iSpindel project documentation. We did not float, calibrate or compare these devices; where sources disagree (Tilt Pro, RAPT battery life), we say so.

ABV calculatorWork out ABV from OG and FG with the standard and high-gravity formulas, hydrometer temperature correction,…Printable brew-day log and recipe sheetFree brew-day log: record recipe, water and salts, mash, gravities, yeast, fermentation temperatures,…

Questions

Tilt vs RAPT Pill: which is more accurate?
Both list ±0.002 SG gravity accuracy. For temperature, KegLand lists ±0.2°C (0.36°F) for the RAPT Pill and Tilt lists ±1°F (±0.5°C). Check either against a hydrometer.
Does the Tilt work in a stainless fermenter or keg?
Stainless blocks Bluetooth, so range drops. Tilt sells the compact Pro Mini for kegs and pressure fermenters (it fits a 1.5 in. tri-clamp port) and the Pico bridge for better range.
How long does the RAPT Pill battery last?
It depends on connection and reporting interval. KegLand quotes about 12 months on Bluetooth at a 60-minute interval and about 2–5 months between charges on Wi-Fi. It recharges over USB-C.
Do I need Wi-Fi for a Tilt?
No. A Tilt sends data over Bluetooth to the Tilt app on a nearby phone or tablet. For remote logging, add a Tilt Pi or the Tilt Pico Wi-Fi bridge.
Is the iSpindel better than a Tilt?
It's cheaper in parts and fully open source with Wi-Fi, but you build, flash and calibrate it yourself, and there's no branded listing in our catalogue. Tilt and RAPT are ready to use.
Can a digital hydrometer replace my regular hydrometer?
It replaces daily sampling, not the reference check. Take a hydrometer reading at pitching and before packaging, and recalibrate the float if the two disagree.

Sources

  1. Tilt Hydrometer: Tilt Pro Mini specifications
  2. Tilt Hydrometer: home page
  3. Grainfather help center: What is the Tilt Hydrometer?
  4. KegLand: RAPT Pill hydrometer and thermometer (Wi-Fi and Bluetooth)
  5. iSpindel open-source project (GitHub)