How to Calculate Car Insurance Premium in India: Formula and Factors

Ask two insurers to quote for the very same car, and you can walk away with numbers that sit thousands of rupees apart. Same make, same model, same city, and yet the premiums refuse to match. To most car owners, this feels random, even a little unfair. It is neither.

Behind that final figure is a handful of moving parts, each of which follows a rule. Once you can see those parts, the premium stops being a mystery. You start to notice when a quote is fair, when an add-on is quietly padding the bill, and where you have room to bring the number down without cutting the cover you actually need.

This guide opens up the premium and shows you exactly how it is built, from the formula itself down to worked examples for a hatchback, an SUV, and a two-wheeler.

The Premium Formula: OD Premium + TP Premium + Add-ons - NCB

A comprehensive car insurance premium is not a single figure pulled out of the air. It is an assembly. Strip away the jargon and the structure looks like this:

Comprehensive Premium = Own Damage Premium + Third-Party Premium + Add-on Costs - NCB and Discounts, and then 18% GST is added on top.

Each block does a different job:

• Own Damage (OD) premium covers damage to your own car from accidents, fire, theft, and natural events. This is the part insurers price differently, so it is where quotes vary.

• Third-Party (TP) premium covers your legal liability if you injure someone or damage their property. It is fixed by the regulator and is identical no matter which company you buy from.

• Add-on costs are the optional extras you choose to bolt on, like zero depreciation. Each one adds to the bill.

• NCB and discounts are subtracted, rewarding you for claim-free years and for choices like a voluntary deductible.

The practical lesson from the formula is this: the third-party portion is fixed, so the real room to shop around and save sits entirely on the own damage side. That is where the rest of this guide spends its time.

How Own Damage Premium Is Calculated

The own damage premium has its own small formula:

Own Damage Premium = (IDV x OD rate) + Add-ons - NCB - Voluntary Deductible Discount.

Two numbers do most of the heavy lifting here: your IDV and the OD rate the insurer applies to it.

IDV x OD Rate

IDV stands for Insured Declared Value. It is the current market value of your car, and it is the ceiling the insurer will pay if the vehicle is stolen or written off. It is worked out as the manufacturer's listed price minus depreciation, with the value of any accessories added in separately.

The OD rate is a percentage the insurer applies to that IDV, usually somewhere around two to three per cent, though it shifts with the engine's cubic capacity, your city zone, and the company's own pricing model. Multiply the IDV by this rate, and you have the base OD premium before any discounts or add-ons.

Here is the trap many people fall into. A higher IDV means a higher premium, so it is tempting to declare a low IDV to save money. Do not. If your car is stolen or totalled, the payout is capped at that low IDV, and you end up short of what a replacement costs. Keep the IDV honest and close to the real market value.

Age of Vehicle Discount

As a car gets older, its IDV falls according to a standard depreciation grid used across the industry. A lower IDV pulls the OD premium down with it, which is why an older car is usually cheaper to insure on the own damage side, even though its repair risk is climbing.

Age of vehicle	Depreciation applied to IDV
Up to 6 months	5%
6 months to 1 year	15%
1 to 2 years	20%
2 to 3 years	30%
3 to 4 years	40%
4 to 5 years	50%
Over 5 years	Mutually agreed between insurer and owner

Once a car crosses five years, there is no fixed depreciation figure. The IDV becomes a value agreed between you and the insurer, based on the car's condition, model demand, and spare-parts availability.

IRDAI Third-Party Premium: Fixed Rates by CC

Third-party cover is the legal minimum every vehicle must carry. Its price is set centrally by the IRDAI based on engine capacity, and it is the same across every insurer in the country. You cannot negotiate it, and no company can offer it cheaper or dearer than the notified rate.

These are the annual third-party premiums for private cars that have been in force since FY 2019-20:

Engine capacity	Annual third-party premium
Not exceeding 1000cc	Rs 2,094
1000cc to 1500cc	Rs 3,416
Above 1500cc	Rs 7,897

A couple of things worth knowing. Electric cars are priced on motor power in kilowatts rather than cc, and they receive a regulator-approved discount as part of the push for cleaner vehicles. Also, a revision of these long-frozen rates has been under discussion, so the applicable figure is always the one in effect on the day your policy starts. It is worth confirming the current rate at renewal rather than assuming last year's number still holds.

How Add-ons Change Your Premium

Add-ons are optional covers that sit on top of your comprehensive policy. Each one widens your protection and, in return, adds to the premium. The trick is buying the ones that suit your car and skipping the rest. The common ones are:

• Zero depreciation: the insurer pays the full cost of replaced parts without deducting for wear and tear. This is the single most valuable add-on for new and near-new cars, and also the one that adds the most to the premium.

• Engine protection: covers engine damage from water ingress or oil leakage, which the base policy excludes. Useful in flood-prone cities.

• Return to invoice: in a total loss or theft, pays you the original invoice value rather than the depreciated IDV. Most relevant in the first few years.

• Roadside assistance: towing, jump-starts, flat-tyre help, and fuel delivery. A small addition for a lot of convenience.

• Consumables cover: pays for items like engine oil, nuts, and coolant that are normally excluded from claims.

• NCB protection: lets you make a limited number of claims without losing your accumulated bonus. Worth it once your NCB is high.

Because every add-on is taxed and priced separately, a policy loaded with covers you will never use can cost far more than a lean one. For an eight-year-old hatchback, zero depreciation and return to invoice add little real value. For a brand-new SUV, they are close to essential.

How NCB Reduces Your Renewal Premium

The No Claim Bonus, or NCB, is a discount you earn for every policy year you finish without making a claim. It is one of the biggest levers you have over your premium, and the slabs are standardised by the IRDAI across all insurers:

Claim-free years	NCB discount
After 1 year	20%
After 2 years	25%
After 3 years	35%
After 4 years	45%
After 5 or more years	50%

One detail decides how much NCB is actually worth to you. It applies only to the own damage premium, never to the fixed third-party portion. So on a car with a Rs 20,000 OD premium, a 35% NCB knocks off Rs 7,000, bringing that component down to Rs 13,000 before GST.

The flip side is a warning. A single claim resets your NCB to zero, and letting your policy lapse for more than 90 days after expiry wipes it out entirely. Years of built-up discount can vanish over one small claim or one missed renewal date, which is why timing your renewal matters as much as driving carefully.

Zone/City Impact on Premium

Where your car is registered changes what you pay on the own damage side. For pricing, India is split into two zones.

Zone A covers the major metros: Ahmedabad, Bengaluru, Chennai, Hyderabad, Kolkata, Mumbai, New Delhi, and Pune. Zone B is every other town, city, and rural area.

Zone A premiums tend to run roughly 10 to 15 per cent higher on the OD component. The reason is straightforward: dense traffic, higher accident frequency, greater theft risk, and costlier repairs all push up the insurer's expected payout in big cities. The third-party premium, being fixed nationally, does not change with your zone at all.

Worked Examples

The figures below are illustrative. The OD rate varies by insurer, so treat these as a guide to how the pieces fit together rather than exact quotes. GST of 18% is applied at the end in each case.

Hatchback

A 1200cc petrol hatchback registered in a Zone A city, with an IDV of Rs 6,00,000 and one claim-free year behind it (20% NCB):

Component	Amount
Base OD premium (approx 2.5% of IDV)	Rs 15,000
Less 20% NCB on OD	- Rs 3,000
Zero depreciation add-on	+ Rs 3,500
Third-party premium (1000-1500cc)	+ Rs 3,416
Sub-total before GST	Rs 18,916
GST at 18%	+ Rs 3,405
Total payable (approx)	Rs 22,321

SUV

An SUV above 1500cc registered in a Zone A city, with an IDV of Rs 16,00,000 and three claim-free years (35% NCB), with two add-ons:

Component	Amount
Base OD premium (approx 2.5% of IDV)	Rs 40,000
Less 35% NCB on OD	- Rs 14,000
Zero depreciation + engine protection	+ Rs 9,000
Third-party premium (above 1500cc)	+ Rs 7,897
Sub-total before GST	Rs 42,890
GST at 18%	+ Rs 7,720
Total payable (approx)	Rs 50,617

Two-Wheeler

The same logic runs through bike insurance, only the numbers are smaller. Take a 160cc motorcycle in a Zone B town, with an IDV of Rs 90,000 and one claim-free year (20% NCB):

Component	Amount
Base OD premium (approx 2% of IDV)	Rs 1,800
Less 20% NCB on OD	- Rs 360
Zero depreciation add-on	+ Rs 500
Third-party premium (150-350cc)	+ Rs 1,366
Sub-total before GST	Rs 3,306
GST at 18%	+ Rs 595
Total payable (approx)	Rs 3,901

Notice how the fixed third-party premium makes up a much larger share of a two-wheeler's bill than a car's. On a low-IDV bike, there is simply less own damage premium for a discount to work on.

How to Get The Fairest Renewal or Insurance Quote

Now that you can see inside the numbers, here is how to use it in your favour when you buy or renew:

1. Set an honest IDV. Keep it close to the real market value. Too low and you are underinsured; too high and you overpay for cover you can never claim.

2. Compare on OD, not TP. Since the third-party rate is identical everywhere, the only meaningful differences between quotes are the own damage premium, the add-ons, and the claim service. Compare those.

3. Buy only the add-ons you need. Match them to your car's age and your city. A new car in a flood-prone metro wants zero depreciation and engine protection; a decade-old runabout may not.

4. Protect and carry your NCB. Avoid small claims that reset it, renew before the 90-day window closes, and carry the bonus forward when you change cars or insurers.

5. Consider a voluntary deductible. Agreeing to pay a fixed amount yourself at claim time lowers your premium. Just keep it to a figure you could comfortably cover.

When you are ready to run the numbers against a live quote, apps such as CarInfo let you compare car insurance options against your own vehicle details, which is the fastest way to see whether a premium is fair or padded. The formula in this guide is your yardstick.

Frequently Asked Questions

1. What is the basic formula for calculating a car insurance premium?

A comprehensive premium is the own damage premium plus the third-party premium plus any add-on costs, minus your NCB and discounts, with 18% GST added at the end. The own damage part itself is the IDV multiplied by the insurer's OD rate.

2. Why do two insurers quote different premiums for the same car?

Because the own damage rate and add-on pricing differ between companies, and each may suggest a slightly different IDV. The third-party portion is identical everywhere, so all the variation sits on the own damage side.

3. What is IDV and how does it affect my premium?

IDV is the current market value of your car and the maximum the insurer pays in a total loss or theft. A higher IDV raises your premium but gives a bigger payout. Declaring an unrealistically low IDV to save money leaves you underinsured.

4. Is the third-party premium the same across all insurers?

Yes. The IRDAI fixes third-party rates by engine capacity, and every insurer must charge the same amount. You cannot bargain on this component.

5. How much can NCB reduce my premium?

NCB ranges from 20% after one claim-free year to 50% after five, and it applies only to the own damage premium. On a car with a high OD premium, that can be worth several thousand rupees a year.

6. Does the third-party premium get the NCB discount?

No. NCB applies only to the own damage premium. The third-party premium is fixed by the regulator and stays the same regardless of your claim history.

7. Why is my car insurance premium so high?

Common reasons are a high IDV, several add-ons, registration in a Zone A metro, a large engine, or a reset NCB after a recent claim. Reviewing each of these usually reveals where the cost is coming from.

8. Does GST apply to car insurance in 2026?

Yes. Motor insurance still attracts 18% GST on the full premium, including add-ons. The 2025 GST changes removed the tax on individual life and health cover but left motor insurance unchanged.

9. How does my city affect the premium?

Cars registered in Zone A metros generally pay 10 to 15 per cent more on the own damage premium due to higher traffic, theft, and repair costs. The third-party premium does not change with location.

10. Do older cars have cheaper premiums?

On the own damage side, usually yes, because a lower IDV from depreciation reduces that component. However, older cars carry higher repair risk, and after five years the IDV becomes a value agreed with the insurer.

11. Which add-ons are actually worth buying?

It depends on the car. Zero depreciation and return to invoice matter most for new cars; engine protection is valuable in flood-prone cities; roadside assistance is a low-cost convenience. Skip add-ons that do not fit your car's age or usage.

12. Can I lower my premium without cutting cover?

Yes. Keep an accurate IDV, protect your NCB, opt for a sensible voluntary deductible, drop add-ons you do not need, and renew on time. These trim the cost without weakening the protection that matters.