CR2032 vs CR2025 vs CR2016 vs CR2430: Real Differences

All four are 3 V lithium–manganese dioxide coin cells built to the IEC 60086 standard. CR2016, CR2025 and CR2032 share a 20 mm diameter and differ only in height — 1.6 mm, 2.5 mm and 3.2 mm — while CR2430 is a wider 24.5 mm cell at 3.0 mm tall. Energizer rates them at 90, 163, 240 and 290 mAh respectively. But capacity is rarely what decides whether a substitution works. This guide covers the two numbers that do: internal resistance under pulse load, and the stack height inside the holder.

The four coin cells side by side

The table below gives the published figures, plus the one column almost every comparison omits — the drain rate each capacity was measured at.

 

Cell	Diameter	Height	Rated capacity	Drain used for rating (to 2.0 V)	Weight*	Typical applications
CR2016	20.0 mm	1.6 mm	90 mAh	30 kΩ (~97 µA)	~1.6 g	Slim key fobs, LED tea lights, thin remotes
CR2025	20.0 mm	2.5 mm	163 mAh	15 kΩ (~193 µA)	~2.6 g	Car remotes, watches, bathroom scales
CR2032	20.0 mm	3.2 mm	240 mAh	15 kΩ (~190 µA)	~3.0 g	PC CMOS/RTC, glucometers, BLE sensors, lab half-cells
CR2430	24.5 mm	3.0 mm	290 mAh	10 kΩ (~290 µA)	~4.2 g	Medical alarms, industrial sensors, some vehicle keys

 

The four ratings are not measured under the same load. Energizer rates the CR2016 at roughly 97 µA and the CR2032 at roughly 190 µA, so "a CR2032 holds 2.7× a CR2016" compares two different tests, not two cells under identical conditions. Run both at the same higher drain and the gap widens, because the thinner cell also carries the higher internal resistance.

What the model number encodes — and what it hides

The code is dimensional, not marketing. Under IEC 60086, "C" is lithium–manganese dioxide chemistry at 3 V nominal, "R" is a round cell, the first two digits give the diameter in millimetres and the last two the height in tenths of a millimetre.

Two things it hides:

• The diameter digits round down. CR2430 and CR2450 are both 24.5 mm across, not 24.0 mm — they differ in height (3.0 versus 5.0 mm) and capacity (about 290 versus 620 mAh).
• The prefix is not always cosmetic. DL2032, ECR2032 and KCR2032 are the same cell under Duracell, Energizer and Kodak codes. BR2032 is not: the "B" denotes carbon monofluoride chemistry, trading capacity and pulse performance for a wider temperature range.

Why CR2032 vs CR2025 vs CR2016 substitutions fail

Substitutions fail mechanically or electrically, not because the smaller cell ran out of charge.

Contact pressure runs out before capacity does

A CR2032 holder is sprung for a 3.2 mm cell. Drop in a CR2025 and the spring sits near the end of its travel, so contact force falls sharply.

The failure is intermittent rather than dead, which makes it harder to diagnose than a flat battery: a fob that works at one metre but not ten, a sensor that resets when the enclosure is knocked, a PC that loses its clock only sometimes. A CR2016 in the same holder leaves a 1.6 mm gap and usually makes no contact at all.

Internal resistance decides pulse behaviour

Energizer puts the starting internal resistance of a fresh CR2032 near 10 Ω. An AAA alkaline sits around 0.3 Ω. Coin cells are a high-impedance source by construction, and a thinner cell — less electrode area, less electrolyte — starts higher still.

That matters the moment a device draws a pulse. Under a 75 Ω pulse (about 30 mA), a CR2032 shows a closed-circuit voltage well below its open-circuit value and reaches a 2 V cutoff far earlier in the discharge than the average-drain curve suggests.

The practical consequence: an open-circuit multimeter reading of 3.0 V tells you almost nothing about a coin cell in a pulsed device. Internal resistance also climbs as the cell discharges, and it climbs early and steeply at very low microamp drains.

Your circuit's cutoff voltage strands capacity

Every capacity figure above is measured down to 2.0 V. A device that stops at 2.4 V never reaches that point, so a share of the rated milliamp-hours is never used — and high-impedance cells waste proportionally more, because their loaded voltage sits lower to begin with.

The "two CR2016 equal one CR2032" myth

Two CR2016 cells stacked do not make a CR2032. They make 3.2 mm of height and 6 V.

Cells in series add voltage. Devices that ship with two CR2016 — some laser pointers, older remotes, LED novelties — are 6 V designs. Feeding 6 V to a 3 V circuit risks damaging it; a single 3 V cell in a 6 V device usually just fails to run. The height coincidence is real; the electrical equivalence is not.

Walkthrough 1: a 60-second load test that beats a voltmeter

A voltmeter alone cannot separate a good coin cell from a tired one, because open-circuit voltage stays near 3 V until very late in the discharge. Add a known load and you measure what the device actually sees.

 

1. Measure open-circuit voltage. A fresh cell reads about 3.2–3.3 V; at or below 2.8 V is suspect, but a healthy reading proves nothing on its own.
2. Bridge the terminals with a 1 kΩ resistor (about 3 mA) and read again after five seconds. A healthy cell holds above roughly 2.9 V.
3. For pulse-driven devices, repeat briefly with a 75 Ω resistor (about 30–40 mA) for under one second — the load class Energizer uses for its own pulse characterisation.
4. Calculate internal resistance: IR = ΔV ÷ ΔI. Energizer's worked example on a fresh CR2032 with a 25 Ω, 50 ms pulse gives (3.279 V − 2.429 V) ÷ (0.097 A − 0.000003 A) ≈ 9 Ω.
5. Interpret. Near 10 Ω is fresh. Several tens of ohms means the cell is finished for pulsed duty, even if it reads 3.0 V at rest and would still run a clock for a year.

 

What to watch out for:

• Do not leave the high-current load connected. It is far above the continuous rating; the cell warms and the reading drifts downward as you watch.
• Passivation will fool you. After years in storage a resistive film forms on the lithium anode, so the first pulse reads badly. A brief load thins it and resistance returns toward normal — test an old cell twice before condemning it.
• Cold is not the same as flat. The recommended range is −30 °C to 60 °C, but voltage and delivered capacity fall well before the lower limit. A fob that fails only on frosty mornings has an impedance problem, not an empty cell.

Walkthrough 2: the emergency shim, and three ways it goes wrong

Shimming a CR2025 into a CR2032 holder works as a temporary fix, but the "just fold some foil" advice online does not survive contact with the numbers.

The gap is 0.7 mm. Standard household aluminium foil is roughly 0.016 mm thick, so closing it takes around 40 folded layers — a wad that will not sit flat and creeps out of position the first time the case is closed.

What actually works:

1. Identify the terminals properly. On a CR-series cell the large can — flat top and entire rim — is positive; the smaller flat disc underneath is negative, isolated by a polymer gasket.
2. Shim only against the flat negative face. Anything that wraps over the rim bridges positive to negative: a dead short, a hot cell and a ruined holder.
3. Use a rigid conductor of known thickness — a 0.5 mm stainless spacer disc from a coin cell case kit, or a punched brass shim — never crumpled foil.
4. Reassemble, then run the load test while pressing on the case. If the loaded voltage jumps as you press, the contact is still marginal.

 

You give up roughly 32% of the runtime (163 mAh against 240 mAh) and add contact resistance in series with a cell that already carries about 10 Ω of its own.

When not to do it: sealed or medical devices, anything safety-critical or under warranty, and any compartment a child can open. The correct cell is a sub-$1 part; the shim is a bridge to the shop, not a repair.

Runtime maths for two real devices

Dividing capacity by average current gives a first estimate. The two cases below show why that estimate is trustworthy in one situation and misleading in the other.

Case A: PC CMOS / real-time clock backup, ~3 µA continuous

 

Cell	Rated capacity	Theoretical runtime at 3 µA	Practical verdict
CR2016	90 mAh	~30,000 h (~3.4 years)	Replace roughly every 3 years
CR2025	163 mAh	~54,000 h (~6.2 years)	Comfortable but not the best fit
CR2032	240 mAh	~80,000 h (~9.1 years)	The standard choice, for good reason
CR2430	290 mAh	~96,000 h (~11 years)	No practical gain — shelf life caps it

 

Shelf life is about 10 years at room temperature, losing roughly 1% of capacity per year, so past about nine years the calendar wins rather than the chemistry — the CR2430 buys nothing here despite storing more. At drains this low, internal resistance also rises early in the discharge, so a cell can be electrically aged while still holding most of its charge.

Case B: BLE sensor, 15 µA average with 8 mA transmit pulses

On paper a CR2032 gives 240 ÷ 0.015 = 16,000 hours, about 1.8 years; a CR2016 gives 6,000 hours, about eight months.

Both are optimistic, because the device cuts off on loaded voltage during a transmit pulse rather than on the average. Engineers commonly derate pulsed coin cell budgets to roughly 60–75% of nameplate [VERIFY against your own measured load profile]. The CR2016 loses far more than the capacity ratio predicts: it starts with higher internal resistance and rises faster, so it trips the cutoff long before it is empty.

What changes when you assemble coin cells in the lab

In battery research the format choice is a stack-height budget, not a capacity decision. CR2032 dominates as the standard half-cell because its 3.2 mm internal envelope leaves the most room for a working stack.

A typical CR2032 case set ships with a 15.8 mm × 1.0 mm stainless spacer and a 15.4 mm × 1.1 mm conical spring — roughly 2.1 mm of hardware inside a 3.2 mm shell before the cathode disc, separator and lithium chip go in.

 

• A CR2025 case removes 0.7 mm from that budget. Labs typically drop to a 0.5 mm or 0.2 mm spacer, or a shorter spring, to stop the crimp over-compressing the stack.
• CR2016 leaves so little spring travel that stack pressure becomes hypersensitive to electrode thickness tolerance — fine for thin films and solid-state pellets, poor for thick, high-loading electrodes.
• CR2430's 24.5 mm shell allows a larger electrode disc, typically 19 mm instead of 14–16 mm, raising absolute capacity and improving signal-to-noise on areal capacity measurements.

 

Three mistakes that quietly ruin datasets:

• Mixing spacer thicknesses within one batch. Different stack pressure gives different interfacial impedance, and it is easy to read that as a material effect.
• Under- or over-crimping. A correctly crimped CR2032 measures close to 3.0–3.2 mm externally; outside that, either the gasket has not sealed or the stack is being crushed.
• Reusing cases. The polymer gasket takes a permanent set on the first crimp and will not seal reliably again.

When this advice does not apply

• Low-drain, non-pulsed devices. For a quartz watch, kitchen scale or digital thermometer the capacity table really is the whole story: fit the thickest cell the holder takes.
• Sustained heat above 60 °C. BR-series carbon monofluoride cells extend the range, at the cost of capacity and pulse performance.
• Rechargeable look-alikes. LIR2032 is 3.6 V and around 40 mAh; it fits the holder and will not behave as your device expects.
• Child-accessible devices. Coin cell ingestion causes severe internal injury within hours — screw-down compartments exist for that reason, and a shim job that defeats one is not an acceptable repair.

Frequently asked questions

Can I use a CR2025 instead  of a CR2032?

Usually yes, temporarily. Both are 3 V and 20 mm wide, so a CR2025 fits electrically. You lose about 32% of the runtime, and the 0.7 mm height shortfall cuts contact pressure, which causes intermittent faults. Use it to get by, then fit the specified cell.

Is a CR2016 just half a CR2032?

No. A CR2016 is half the height but delivers about 90 mAh against 240 mAh — roughly 37%, not 50%. It also has higher internal resistance, so it performs disproportionately worse in devices that draw current in pulses, such as key fobs and wireless sensors.

Are CR2430 and CR2450 interchangeable?

Only if the holder has the depth. Both are 24.5 mm across, but a CR2430 is 3.0 mm tall at about 290 mAh and a CR2450 is 5.0 mm at about 620 mAh. A CR2430 rattles in a CR2450 holder; a CR2450 will not close in a CR2430 compartment.

Why does my new coin cell read 3 V but the device still will not work?

Open-circuit voltage stays near 3 V almost to the end of a coin cell's life. The device is probably failing on loaded voltage during a current pulse, or on contact pressure. Run the load test above — a healthy cell holds above roughly 2.9 V under a 1 kΩ load.

How long do coin cells last in storage?

About 10 years at normal room temperature and humidity, losing roughly 1% of capacity per year. Long storage also builds a passivation layer on the lithium anode, which raises internal resistance temporarily. A short load usually clears it and performance returns to normal.

Which coin cell size is standard for battery research?

CR2032 is the default half-cell format. Its 3.2 mm internal envelope accommodates a full stack — cathode disc, separator, lithium chip, spacer and spring — with enough spring travel to hold consistent stack pressure. CR2025 and CR2016 suit deliberately tighter stacks.

Conclusion

CR2016, CR2025 and CR2032 differ only in height, and that height buys three things at once: capacity, lower internal resistance, and enough thickness to keep the holder spring properly compressed. CR2430 sits outside the family at 24.5 mm and is never a drop-in for any of them.

For low-drain devices, fit the thickest cell that fits. For anything that transmits or wakes on a timer, test under load before trusting a voltage reading.

Next step: run the 60-second load test on the cell in your device before buying a replacement. If the loaded voltage collapses below 2.4 V, the cell is done regardless of what the voltmeter says at rest. If it holds and the device still misbehaves, the problem is contact pressure, not chemistry.