{"success":true,"version":"v1","request":{"tool":"get_calculator_schema","calculator_id":"gravel"},"result":{"entity_type":"calculator","id":"gravel","calculator_id":"gravel","canonical_url":"https://tttkmbb.com/construction/gravel","name":"Gravel Calculator","title":"Gravel, Sand, Mulch and Topsoil Calculator – Volume in m³ / Cubic Yards and Weight in Tonnes","category":"construction","category_name":"Construction & Home","tool_name":"estimate_gravel_volume","featured_mcp_tool":false,"description":"Computes the volume of loose aggregate needed to cover an area to a given depth and converts it to weight with a typical bulk density for gravel, crushed stone, sand, topsoil or mulch (or a custom density).","use_when":"You need to order gravel, crushed stone, sand, topsoil or bark mulch by volume (m³, yd³) or by weight (tonnes, US tons) for a driveway, path, bed or sub-base.","do_not_use_when":"The material is concrete (use concrete-slab) or you need the density of a specific product: use the supplier's figure via material = custom and density_t_per_m3.","inputs":[{"name":"unit_system","label":"Unit system","type":"enum","required":false,"default":"metric","values":[{"value":"metric","label":"Metric (m, cm, mm, m²)","aliases":["si","metres","meters"]},{"value":"imperial","label":"Imperial / US customary (ft, in, ft²)","aliases":["us","feet","inches"]}],"description":"Unit system of the length inputs (metric: m / cm / mm; imperial: ft / in). Outputs are reported in both systems.","example":"metric"},{"name":"length","label":"Length","type":"number","unit":"m or ft","required":false,"max":10000,"exclusive_min":0,"description":"Length of the area (m or ft). Give length and width, or area.","example":10},{"name":"width","label":"Width","type":"number","unit":"m or ft","required":false,"max":10000,"exclusive_min":0,"description":"Width of the area (m or ft).","example":5},{"name":"area","label":"Area","type":"number","unit":"m² or ft²","required":false,"exclusive_min":0,"description":"Area to cover (m² or ft²); used instead of length × width when given."},{"name":"depth","label":"Depth","type":"number","unit":"cm or in","required":true,"max":500,"exclusive_min":0,"description":"Depth of the layer in centimetres (metric) or inches (imperial). Typical: 5 cm / 2 in decorative gravel, 10–15 cm / 4–6 in driveway base, 7.5 cm / 3 in mulch.","example":5},{"name":"material","label":"Material","type":"enum","required":false,"default":"gravel","values":[{"value":"gravel","label":"Gravel / pea gravel (1.6 t/m³)","aliases":["pea gravel","aggregate"]},{"value":"crushed_stone","label":"Crushed stone / road base (1.6 t/m³)","aliases":["crushed rock","road base","hardcore"]},{"value":"sand","label":"Sand, dry (1.5 t/m³)"},{"value":"topsoil","label":"Topsoil / loose earth (1.2 t/m³)","aliases":["soil","dirt","earth"]},{"value":"mulch","label":"Bark mulch / wood chips (0.4 t/m³)","aliases":["bark","wood chips"]},{"value":"custom","label":"Custom density (use density_t_per_m3)"}],"description":"Selects a typical loose bulk density in tonnes per cubic metre.","example":"gravel"},{"name":"density_t_per_m3","label":"Custom density","type":"number","unit":"t/m³","required":false,"max":10,"exclusive_min":0,"description":"Bulk density in tonnes per m³ (= kg/L); required for material = custom and overrides the preset otherwise.","example":1.6}],"outputs":[{"name":"area_m2","label":"Area","type":"number","unit":"m²","decimals":2,"description":"Area covered."},{"name":"volume_m3","label":"Volume","type":"number","unit":"m³","decimals":3,"description":"area × depth."},{"name":"volume_cubic_yards","label":"Volume","type":"number","unit":"yd³","decimals":3,"description":"Same volume in cubic yards."},{"name":"volume_cubic_feet","label":"Volume","type":"number","unit":"ft³","decimals":2,"description":"Same volume in cubic feet."},{"name":"density_used_t_per_m3","label":"Density used","type":"number","unit":"t/m³","decimals":2,"description":"Bulk density applied."},{"name":"weight_tonnes","label":"Weight","type":"number","unit":"t","decimals":3,"description":"volume_m3 × density (metric tonnes)."},{"name":"weight_kg","label":"Weight","type":"number","unit":"kg","decimals":0,"description":"Weight in kilograms."},{"name":"weight_us_tons","label":"Weight","type":"number","unit":"US short tons","decimals":3,"description":"Weight in US short tons (1 t = 1.10231 short tons)."}],"input_schema":{"type":"object","properties":{"unit_system":{"description":"Unit system of the length inputs (metric: m / cm / mm; imperial: ft / in). Outputs are reported in both systems.","type":"string","enum":["metric","imperial"],"default":"metric","examples":["metric"]},"length":{"description":"Length of the area (m or ft). Give length and width, or area. Unit: m or ft.","type":"number","maximum":10000,"exclusiveMinimum":0,"examples":[10],"x-unit":"m or ft"},"width":{"description":"Width of the area (m or ft). Unit: m or ft.","type":"number","maximum":10000,"exclusiveMinimum":0,"examples":[5],"x-unit":"m or ft"},"area":{"description":"Area to cover (m² or ft²); used instead of length × width when given. Unit: m² or ft².","type":"number","exclusiveMinimum":0,"x-unit":"m² or ft²"},"depth":{"description":"Depth of the layer in centimetres (metric) or inches (imperial). Typical: 5 cm / 2 in decorative gravel, 10–15 cm / 4–6 in driveway base, 7.5 cm / 3 in mulch. Unit: cm or in.","type":"number","maximum":500,"exclusiveMinimum":0,"examples":[5],"x-unit":"cm or in"},"material":{"description":"Selects a typical loose bulk density in tonnes per cubic metre.","type":"string","enum":["gravel","crushed_stone","sand","topsoil","mulch","custom"],"default":"gravel","examples":["gravel"]},"density_t_per_m3":{"description":"Bulk density in tonnes per m³ (= kg/L); required for material = custom and overrides the preset otherwise. Unit: t/m³.","type":"number","maximum":10,"exclusiveMinimum":0,"examples":[1.6],"x-unit":"t/m³"}},"additionalProperties":false,"required":["depth"]},"output_schema":{"type":"object","properties":{"area_m2":{"description":"Area covered. Unit: m².","type":"number","x-unit":"m²"},"volume_m3":{"description":"area × depth. Unit: m³.","type":"number","x-unit":"m³"},"volume_cubic_yards":{"description":"Same volume in cubic yards. Unit: yd³.","type":"number","x-unit":"yd³"},"volume_cubic_feet":{"description":"Same volume in cubic feet. Unit: ft³.","type":"number","x-unit":"ft³"},"density_used_t_per_m3":{"description":"Bulk density applied. Unit: t/m³.","type":"number","x-unit":"t/m³"},"weight_tonnes":{"description":"volume_m3 × density (metric tonnes). Unit: t.","type":"number","x-unit":"t"},"weight_kg":{"description":"Weight in kilograms. Unit: kg.","type":"number","x-unit":"kg"},"weight_us_tons":{"description":"Weight in US short tons (1 t = 1.10231 short tons). Unit: US short tons.","type":"number","x-unit":"US short tons"}}},"formula":"area = length × width (or area); volume_m³ = area_m² × depth_m; yd³ = m³ / 0.764555; tonnes = m³ × density_t_per_m³; short tons = tonnes × 1.10231. Densities: gravel 1.6, crushed stone 1.6, sand 1.5, topsoil 1.2, mulch 0.4 t/m³.","method":"Loose bulk densities vary with moisture and grading (dry gravel ≈ 1.68 t/m³, dry sand ≈ 1.56 t/m³, loose earth ≈ 1.22 t/m³ per Engineering ToolBox); compacted sub-base settles by 10–20 %, so order extra for compacted layers.","sources":[{"name":"Engineering ToolBox – Densities of dirt, mud, gravel and sand","url":"https://www.engineeringtoolbox.com/dirt-mud-densities-d_1727.html","type":"reference","retrieved_at":"2026-09-23"},{"name":"Wikipedia – Bulk density","url":"https://en.wikipedia.org/wiki/Bulk_density","type":"reference","retrieved_at":"2026-09-23"}],"freshness":{"type":"static","max_age_seconds":null,"note":"Deterministic formula with fixed constants; results never go stale. Inputs supplied by the caller determine the output."},"examples":[{"name":"10 m × 5 m of gravel, 5 cm deep","inputs":{"unit_system":"metric","length":10,"width":5,"depth":5,"material":"gravel"},"expected":{"area_m2":50,"volume_m3":2.5,"volume_cubic_yards":3.27,"volume_cubic_feet":88.29,"density_used_t_per_m3":1.6,"weight_tonnes":4,"weight_kg":4000,"weight_us_tons":4.409},"url":"https://tttkmbb.com/api/v1/calculate/gravel?unit_system=metric&length=10&width=5&depth=5&material=gravel"},{"name":"20 ft × 10 ft of mulch, 3 in deep","inputs":{"unit_system":"imperial","length":20,"width":10,"depth":3,"material":"mulch"},"expected":{"area_m2":18.58,"volume_cubic_feet":50,"volume_cubic_yards":1.852,"volume_m3":1.416,"weight_tonnes":0.566,"weight_us_tons":0.624},"url":"https://tttkmbb.com/api/v1/calculate/gravel?unit_system=imperial&length=20&width=10&depth=3&material=mulch"}],"faq":[{"q":"Do suppliers sell by weight or volume?","a":"Bulk aggregates are usually sold by the tonne or by the cubic yard/metre; a bulk bag holds about 0.5 m³ (≈ 0.8 t of gravel). Use whichever figure matches the supplier's price list."},{"q":"How much extra should I order?","a":"Add 5–10 % for uneven ground and spillage, and 10–20 % more for layers that will be compacted (road base, sub-base under paving)."}],"tags":["gravel calculator","cubic yards of gravel","tonnes of gravel","mulch calculator","topsoil calculator","sand calculator"],"related":[{"calculator_id":"concrete-slab","reason":"Concrete poured on the sub-base."},{"calculator_id":"volume","reason":"Convert between m³, yd³ and litres."},{"calculator_id":"density-mass-volume","reason":"Mass from volume and density for other materials."}],"links":{"html":"https://tttkmbb.com/construction/gravel","markdown":"https://tttkmbb.com/construction/gravel.md","json":"https://tttkmbb.com/construction/gravel.json","api":"https://tttkmbb.com/api/v1/calculate/gravel","schema":"https://tttkmbb.com/api/v1/calculators/gravel","openapi":"https://tttkmbb.com/openapi.json","mcp":"https://tttkmbb.com/mcp"},"version":"v1","updated_at":"2026-09-23"},"timestamp":"2026-09-23T23:32:17Z","next_actions":[{"tool":"run_calculator","calculator_id":"gravel","reason":"Run Gravel Calculator with the inputs above."}],"links":{"markdown":"https://tttkmbb.com/construction/gravel.md"}}