Quick answer
Buy the ZOLL AED Plus if compression quality matters, because it measures CPR depth and rate in real time and the Philips OnSite does not, and because it costs about $500 less to own over 10 years. Buy the Philips HeartStart OnSite if weight and simplicity matter most, at 3.3 lbs versus 6.7 lbs and with an 8-year warranty. New, the Philips is cheaper to buy. Recertified, both are about $875, which turns the decision into pure features.
These are the two most-bought AEDs in the United States, and almost every comparison of them stops at the spec sheet. That is the wrong place to stop. The Philips OnSite has the lower sticker price, and it is the more expensive device to keep in service, because its pads expire every 2 years and its battery every 4, against 5 years for both consumables on the ZOLL. Over a realistic 10-year deployment that gap is larger than the price difference you were comparing in the first place. This page runs those numbers, corrects the spec errors other comparison charts publish, and covers the case nobody else does: what happens when both units cost the same recertified.
ZOLL AED Plus
Wins on rescue quality and running cost
- Real CPR Help measures depth and rate
- 5-year battery and 5-year pads
- About $330 in consumables over 10 years
- Semi-automatic or fully automatic
- IP55 dust and water rating
Philips HeartStart OnSite
Wins on weight, simplicity and warranty
- 3.3 lbs, roughly half the ZOLL
- 8-year manufacturer warranty
- Lower new price
- Pads pre-connected, no lid
- Semi-automatic only
Side by side: the specs that actually differ
Quick answer
The real differences are CPR feedback, weight, consumable life, and whether a fully automatic version exists. Both are FDA-approved, both self-test, and both need a separate pediatric accessory.
| Specification | ZOLL AED Plus | Philips HeartStart OnSite (M5066A) |
|---|---|---|
| CPR feedback | Real CPR Help, measures compression depth and rate, metronome 60 to 100 CPM | Voice coaching and metronome only, no compression sensing |
| Weight | 6.7 lbs (3.1 kg) | 3.3 lbs (1.5 kg) with battery and pads |
| Ingress rating | IP55 | IP21 |
| Battery | 10 × Type 123A lithium, 5-year standby, 225 shocks | M5070A lithium, 4-year installed life |
| Pads | CPR-D-padz one-piece, 5-year shelf life | M5071A SMART Pads cartridge, 2-year shelf life |
| Pediatric | Pedi-padz II, sold separately | Infant/Child SMART Pads cartridge, sold separately, reduces energy to about 50 J |
| Fully automatic option | Yes, semi and fully automatic | No, semi-automatic only |
| Display | Optional LCD with moving bar | None, audio and visual prompts |
| Warranty (new) | Up to 7 years with registration | 8 years |
| Energy | Escalating 120 / 150 / 200 J | SMART Biphasic, 50 J pediatric |
The 10-year cost of ownership nobody publishes
Quick answer
Over 10 years the ZOLL AED Plus costs roughly $330 in replacement pads and batteries. The Philips HeartStart OnSite costs roughly $838. The Philips is cheaper to buy and about $500 more expensive to keep.
This is the number that should decide the purchase, and no comparison page in this search publishes it. The mechanism is simple: the ZOLL runs both of its consumables on a 5-year clock, so each is replaced once in a decade. The Philips runs a 4-year battery and 2-year pads, so you replace the battery twice and the pads four times in the same window.
| Consumable | ZOLL AED Plus | Philips OnSite |
|---|---|---|
| Battery life and cost | 5 years, about $100 per set | 4 years, about $249 |
| Battery replacements in 10 years | 1 | 2 |
| Pad life and cost | 5 years, about $230 | 2 years, about $85 |
| Pad replacements in 10 years | 1 | 4 |
| Approximate 10-year consumable cost | ~$330 | ~$838 |
Assumptions: adult pads only, replacement at the end of each stated shelf life, prices verified from authorized listings in August 2026 and rounded. Pediatric pads are extra on both units and are not included here. The practical read: if you are buying new, the Philips saves you roughly $500 upfront and gives it back over the following decade. If you plan to keep the unit its full service life, that changes the answer. Run your own configuration, including multiple units, in our AED Cost Calculator.
The case nobody covers: both cost $875 recertified
Quick answer
Recertified, the ZOLL AED Plus and the Philips OnSite both sell for about $875 with a 3-year warranty and new pads and battery. At identical prices the ZOLL wins on CPR feedback and running cost, and the Philips wins on weight and simplicity.
Every comparison of these two models compares new units, where the Philips is roughly $500 cheaper. That price gap disappears entirely in the recertified market. Both models are the most commonly recertified AEDs in the US, and both land at about $875 with a documented analyzer test, new genuine pads and battery, and a 3-year warranty. Verified August 2026:
| Model | New | Recertified | Recertified warranty |
|---|---|---|---|
| ZOLL AED Plus | ~$2,082 | $875 | 3-year |
| Philips HeartStart OnSite | ~$1,529 to $1,589 | $875 | 3-year |
Once the price is identical, the decision is purely about what the device does. On that basis the ZOLL AED Plus is the better buy for most organizations, because Real CPR Help addresses the single biggest failure point in a real rescue and the running cost is lower. The Philips OnSite remains the better buy where a lighter, simpler unit will realistically get used by an untrained person. Read the detail in our recertified ZOLL AED Plus review and recertified Philips OnSite review, or the category overview in the recertified AED guide.
Buy either, recertified, at $875
Both models recertified with a documented 9-point analyzer test, new genuine pads and battery, a 3-year warranty, and free shipping. Same FDA-approved devices as new.
What other comparison charts get wrong
Quick answer
Two errors are common in published AED comparison charts: listing the Philips OnSite as available in a fully automatic version, and listing its ingress rating as not applicable. The OnSite is semi-automatic only, and it is rated IP21.
We checked the widely cited comparison charts against manufacturer documentation in August 2026 and found the same mistakes repeated:
| Common claim | Correct |
|---|---|
| Philips OnSite is available "semi or fully automatic" | All HeartStart OnSite models are semi-automatic only. The rescuer presses the shock button. The ZOLL AED Plus is the one that offers both |
| Philips OnSite ingress rating "N/A" | The OnSite is rated IP21. It is protected against dripping water and larger particles, not dust or jets. The ZOLL AED Plus is IP55 |
| The two devices are close on running cost | They are not. The Philips costs roughly two and a half times more in consumables over 10 years because of its 2-year pads |
If a chart gets the automatic option wrong, treat its other rows with the same caution. Every spec on this page is checked against manufacturer documentation, and we date our prices.
Which should you buy?
| If your situation is… | Buy | Why |
|---|---|---|
| Workplace or lay-responder team, compression quality matters | ZOLL AED Plus | Real CPR Help measures depth and rate and corrects the rescuer live |
| Home or small office, untrained responder | Philips OnSite | Half the weight, pads pre-connected, simplest interface made |
| You will keep the unit its full service life | ZOLL AED Plus | About $500 less in consumables over 10 years |
| You want the longest manufacturer warranty | Philips OnSite | 8 years versus up to 7 with registration |
| Outdoor, dusty or wet environment | ZOLL AED Plus | IP55 against IP21 |
| You want the device to shock without a button press | ZOLL AED Plus | The OnSite has no fully automatic version |
Still deciding? Run the Find Your Perfect AED quiz, or read the full reviews: ZOLL AED Plus review and Philips HeartStart OnSite review. For rugged and pediatric needs, compare the Philips FRx. For the newest ZOLL with a touchscreen, see the ZOLL AED 3 review. Full specs across every brand are on our AED comparison tool.
Both are FDA-approved
Sudden cardiac arrest kills more than 356,000 people outside hospitals each year in the US, and survival falls roughly 10 percent for every minute without defibrillation (American Heart Association). Both devices are Class III medical devices approved through FDA Premarket Approval, so neither is a compliance compromise. Placement matters as much as the choice: OSHA response-time guidance applies to both, and requirements vary by location, so check our AED laws by state guide. To size how many units your site needs, use the AED Quantity Calculator.
ZOLL AED Plus vs Philips OnSite FAQ
Which is better, the ZOLL AED Plus or the Philips HeartStart OnSite?
The ZOLL AED Plus where compression quality matters, because it measures CPR depth and rate and the Philips does not, and because it costs about $500 less to own over 10 years. The Philips OnSite where weight and simplicity matter, at half the weight with an 8-year warranty. Recertified, both cost about $875, which makes it a pure feature decision.
Does the Philips HeartStart OnSite give CPR feedback?
No. It gives voice coaching and a metronome, but it does not measure compression depth or rate. The ZOLL AED Plus measures both and tells the rescuer to push harder or maintain.
Which AED is cheaper to own over 10 years?
The ZOLL AED Plus, at roughly $330 in consumables against roughly $838 for the Philips OnSite, because the ZOLL’s battery and pads both last about 5 years while the Philips uses a 4-year battery and 2-year pads.
Is the Philips OnSite available as a fully automatic AED?
No. All HeartStart OnSite models are semi-automatic. The ZOLL AED Plus comes in both semi-automatic and fully automatic versions.
How do they handle children?
Both need a separate pediatric accessory. The ZOLL uses Pedi-padz II and the Philips uses an Infant/Child SMART Pads cartridge that reduces energy to about 50 joules. Neither includes pediatric capability in the standard pad.
Which is lighter?
The Philips OnSite, at 3.3 lbs with battery and pads against 6.7 lbs for the ZOLL AED Plus.
The one-line decision
If your responders will be doing chest compressions under stress, buy the ZOLL AED Plus. If the unit needs to be light, simple and grabbed by anyone, buy the Philips HeartStart OnSite. Recertified, both are about $875, so choose on the feature, not the price.
References
- ZOLL Medical, AED Plus technical specification sheet (weight, IP55, Real CPR Help, Type 123A battery, CPR-D-padz, Pedi-padz II, energy settings).
- Philips, HeartStart OnSite (M5066A) product documentation (weight, IP21, SMART Pads, M5070A battery, Infant/Child cartridge, semi-automatic operation).
- American Heart Association, Cardiac Arrest statistics and Chain of Survival, 2024.
- US FDA, Automated External Defibrillators (AEDs) and Premarket Approval.
- OSHA, Cardiac Arrest and AEDs in the workplace.
- Pricing for new, recertified and replacement consumables verified live from authorized listings on 13 August 2026.
Updated August 2026 · Reviewed by the AED Brand Review Editorial Team · Prices verified live and may change. Confirm current pricing on the linked product pages before purchase.
