Don't trust the badge. Check the result.

These regression cases publish both inputs and expected outputs. The button below calls the live public API from your browser and checks the current production responses against the published expectations.

Download JSON cases

What this proves — and what it doesn't

A passing case shows that the live API produced the listed result for the listed inputs at the time you ran it. It does not prove that every possible input is correct or that an estimate is appropriate for every real-world situation. Formula assumptions remain documented on the human calculator pages.

Seller profit: fees and shipping

GET /api/v1/seller-profit?sale=200&buy=50&fee_pct=13&shipping=20

Expected field	Expected value
`selling_fees`	`26`
`profit`	`104`
`roi_percent`	`208`
`profit_margin_percent`	`52`
`break_even_sale_price`	`80.46`

Not run in this browser.

Trip gas cost

GET /api/v1/trip-cost?miles=300&mpg=30&gas_price=3.25&tolls=0&people=1

Expected field	Expected value
`gallons`	`10`
`fuel_cost`	`32.5`
`total_trip_cost`	`32.5`
`cost_per_mile`	`0.1083`

Not run in this browser.

Electricity cost

GET /api/v1/electricity-cost?watts=1500&hours_per_day=5&days_per_month=30&rate_per_kwh=.18&quantity=1&duty_cycle_pct=100

Expected field	Expected value
`kwh_per_day`	`7.5`
`cost_per_day`	`1.35`
`cost_per_month`	`40.5`

Not run in this browser.

EV vs gas energy cost

GET /api/v1/ev-vs-gas?miles_per_month=1000&ev_kwh_per_100_miles=30&electricity_rate=.18&charging_efficiency_pct=90&gas_mpg=30&gas_price=3.5

Expected field	Expected value
`ev_cost_per_month`	`60`
`gas_cost_per_month`	`116.67`
`monthly_difference_gas_minus_ev`	`56.67`

Not run in this browser.

Marketing metrics

GET /api/v1/marketing-metrics?spend=1500&impressions=100000&clicks=2500&conversions=100&revenue=5000

Expected field	Expected value
`cpc`	`0.6`
`cpm`	`15`
`cpa`	`15`
`ctr_percent`	`2.5`
`conversion_rate_percent`	`4`
`roas`	`3.3333`

Not run in this browser.

Business break-even point

GET /api/v1/break-even-point?fixed_costs=5000&price_per_unit=80&variable_cost_per_unit=50

Expected field	Expected value
`contribution_per_unit`	`30`
`break_even_units`	`167`
`break_even_revenue`	`13360`

Not run in this browser.

Customer LTV:CAC

GET /api/v1/customer-ltv-cac?average_order_value=80&purchases_per_year=4&customer_lifespan_years=3&gross_margin_pct=50&cac=75

Expected field	Expected value
`lifetime_revenue`	`960`
`gross_profit_ltv`	`480`
`ltv_cac_ratio`	`6.4`

Not run in this browser.

Salary to hourly

GET /api/v1/salary-to-hourly?annual_salary=60000&hours_per_week=40

Expected field	Expected value
`hourly_equivalent`	`28.8462`
`weekly_equivalent`	`1153.85`
`monthly_equivalent`	`5000`

Not run in this browser.

Percentage change

GET /api/v1/percentage-change?original=100&new_value=125

Expected field	Expected value
`difference`	`25`
`percentage_change`	`25`
`direction`	`"increase"`

Not run in this browser.

Days between dates

GET /api/v1/date-difference?start_date=2026-09-01&end_date=2026-09-30

Expected field	Expected value
`signed_days`	`29`
`absolute_days`	`29`
`end_is_on_or_after_start`	`true`

Not run in this browser.

Square footage

GET /api/v1/square-footage?length=12&width=10

Expected field	Expected value
`area_square_feet`	`120`

Not run in this browser.

Dimensional weight

GET /api/v1/dimensional-weight?length_inches=18&width_inches=12&height_inches=10&dim_divisor=139&actual_weight=8

Expected field	Expected value
`package_volume_cubic_inches`	`2160`
`dimensional_weight`	`15.5396`
`higher_comparison_weight`	`15.5396`

Not run in this browser.