Lower vs higher deductible — breakeven, expected annual savings, and horizon outlook.
Claim frequency is an assumption based on your driving record and risk profile — typical US private-auto values run 0.05–0.30 claims per year. The breakeven number assumes the only difference between policies is the deductible; in practice, raising the deductible can also affect roadside, rental, and gap-coverage clauses depending on the carrier.
Auto-insurance shoppers face a quietly expensive choice every renewal: how high a deductible to take. Carriers happily price their policies along a multi-rung ladder — 250, 500, 1000, 1500, 2000, sometimes 2500 dollars or euros — and each step up shaves a measurable slice off the annual premium. The catch is that the deductible is what you pay out of pocket every time you file a claim, so the higher rung is only the better choice statistically when the premium savings outrun the extra you would have shouldered after a typical claim. The arithmetic that bridges those two cash flows is small enough to hide on a single envelope, but it is exactly where most drivers misjudge their own risk. This calculator stares straight at it: feed in two real quotes from your renewal letter, an honest estimate of how often you actually file claims, and a planning horizon, and it returns the breakeven year, the expected annual savings, and the cumulative cost curves of each strategy over the horizon you picked.
Let low_premium and high_premium be the annual premiums under the two deductible options, and low_deductible and high_deductible the deductible amounts themselves. The headline numbers are:
deductible_delta = high_deductible − low_deductible premium_savings_per_yr = low_premium − high_premium breakeven_years = deductible_delta / premium_savings_per_yr
If your premium did not actually drop when you raised the deductible, the breakeven is undefined and the higher deductible is dominated. Assuming it did drop, multiply your honest claim frequency by the deductible delta to get the expected extra out of pocket per year:
expected_extra_per_yr = claim_frequency × deductible_delta net_savings_per_yr = premium_savings_per_yr − expected_extra_per_yr horizon_savings = net_savings_per_yr × horizon_years
When net savings are positive, the higher deductible is statistically the better bet across the horizon. When they are negative, the premium saving is too small to cover the expected claim cost and the lower deductible is the right call. The calculator also plots two cumulative cost lines, low_premium × t + claim_frequency × low_deductible × t against the same shape with the high values, so you can see at exactly which year the cheaper strategy actually starts paying off.
The form is split into three blocks. Premiums: type in the annual premium your carrier quoted under the low deductible and the annual premium under the high deductible. Use the same coverage profile on both quotes, otherwise you are comparing apples and oranges; the only field you should be flexing is the deductible. Deductibles: enter the two deductible amounts those quotes correspond to. Claim assumption: pull the slider to your honest expected claim frequency. The 0.10 default means one claim every ten years, which is roughly the long-run national average for US private auto comprehensive plus collision combined. If you have filed two claims in the last five years, you are at 0.40 and the slider should reflect that; if you have a perfectly clean fifteen-year record, 0.05 is more honest. Pick a comparison horizon — five years for short-term planning, ten for the typical renewal cadence, twenty for a young driver projecting out to mid-career. The result panel returns the breakeven in years, the annual premium savings, the deductible delta, the expected extra annual claim cost, the net annual savings, the cumulative horizon savings, and a verdict sentence.
Standard renewal letter offers $1,800 with a $500 deductible and $1,650 with a $1,000 deductible. The premium savings are $150/yr, the deductible delta is $500. Mechanical breakeven is 500 ÷ 150 = 3.33 years — in three and a third years of savings, you have re-earned the bigger deductible. With a 0.10 claim frequency, expected extra out of pocket is 0.10 × 500 = $50/yr, leaving $100 of net savings every year. Across a ten-year horizon that is $1,000 you genuinely keep, on top of the slightly cleaner cash flow on years where you did not file. Now flex one input: leave everything the same but raise the claim frequency to 0.30 (a driver who files about every three years). Expected extra is now 0.30 × 500 = $150/yr, exactly cancelling the premium savings — net savings drop to zero. At 0.40, the lower deductible is statistically better even though the breakeven year still says 3.3.
The single most common error is conflating breakeven with profitability. Breakeven only tells you the year at which the premium savings cover the deductible delta in the worst-case event of one claim. If your real claim frequency is well below 1.0/yr — and almost everyone's is — the higher deductible can be profitable far before that year shows up.
A second is claim-frequency calibration. Industry tables are easy to find but they are population averages; your number depends on your driving record, region, vehicle, and storage. Garaging in a hail-prone Texas county pushes comprehensive frequency above 0.20 even with a clean record; suburban garage parking with a ten-year-old commuter on a low-mileage policy can sit at 0.05.
Third, partial vs full deductible application by peril muddies the math. Comprehensive (theft, hail, glass) and collision deductibles are usually separate, and some perils — notably full-glass replacement — skip the deductible entirely on many US carriers. The calculator assumes one deductible applied per claim; if your policy is split, run the math twice.
Fourth, deductible stacking on multi-peril claims. A single hailstorm that damages glass and panels may trigger only the comprehensive deductible, but a collision that also breaks glass typically triggers both. Drivers who have never filed a multi-peril claim underestimate this.
Fifth, the diminishing-deductible rider. Several US carriers (Nationwide's Vanishing Deductible, Allstate's Deductible Rewards) reduce your collision deductible by $100 each year you go claim-free, which can shrink the effective deductible delta over the horizon. The calculator's static-deductible assumption misses this; if your policy carries the rider, treat the high deductible as decaying linearly toward zero across the horizon.
In the United States the deductible applies per incident rather than per year, so a driver with two claims in one year pays twice. The default on most policies is $500, with $1,000 increasingly common; carriers usually offer $250, $500, $750, $1,000, $1,500, $2,000, $2,500. In France the equivalent concept is the franchise, with two flavours: franchise absolue (flat amount you always pay, the same shape as the US deductible) and franchise relative (you pay nothing if damages exceed the franchise, otherwise no payout — rare today but historically present in some tous risques contracts). In the United Kingdom the deductible is split between compulsory excess (set by the insurer for risk-rating reasons, immutable) and voluntary excess (chosen by the policyholder for the discount); only the voluntary part is the lever this calculator targets. In Canada and Australia the structure mirrors the US per-incident model. Whichever jurisdiction you are in, the trade-off is identical: a slightly higher self-insured exposure in exchange for a lower premium, with the math in this calculator answering the only question that matters — over the horizon you actually plan to keep the policy, do the premium savings exceed the expected claim cost?